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3.0 V6 / Caravan Valve Stem Seal / Timing Belt Installation Notes

If your Chrysler, Plymouth, or Dodge product has a 3.0 liter Mitsubishi V-6, and smokes at idle or startup but not while cruising, you may be able to fix it yourself for under $200.

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Table of Contents


The Story

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  • My wife and I bought my in-laws' 1988 Dodge Caravan with 108,000 miles on it. It was using oil, and visibly smoking when idling. On our trip across the country with the vehicle, it used about a quart every 900 miles or so. In Los Angeles city traffic, I'd guess the consumption increased to a quart every 500 miles. This makes sense to me: if the valve stem seals were at fault, then they'd lose the most oil during highest intake manifold vacuum - during idle and off-throttle engine braking. With the throttle butterfly slammed shut, the vacuum gets high enough to draw a significant amount of air (and oil) from inside the head and past the valve stem seals, stems and guides. When accelerating from a traffic light after a couple minute stop, our Caravan consistently left a nice blue ghost of itself. There was never visible smoke during cruise.
  • When we initially considered buying the minivan from my in-laws, I considered entire engine fixes. I found a very impressive shop in Burbank, California which "remanufactured" engines. They had been a jobber machine shop for years, doing work for other shops that pulled engines out of customer cars - they decided to do the whole thing themselves. They're adamant to point out that "remanufacturing" is not "rebuilding." Their procedures are thorough: for example, they magnaflux and shot-peen the crank and rods as a matter of course. Most impressive, they invited potential customers to visit the facility. I took a friend who also does his own automotive work, knowing he'd also enjoy the tour and might also be a potential customer for an commercial engine rebuild. I was convinced of the shop's integrity after the tour and discussion with the "guide." Their facility was immaculate and huge. Bottom line: for a "turnkey" job, where the customer drops off the vehicle and picks it up in about a week, a 3 liter Mistubishi V-6 Caravan will run you about $2800. This includes a 36 month, 36,000 mile warranty, which also covers removal/installation. If I chose to do the engine pulling myself, and drop off the long block, they'd charge about $1800, warranting the engine only for 12 months, 12,000 miles.
  • I'm a hobbyist mechanic. For various reasons, I haven't had anyone work on a vehicle I owned (except air conditioning work) in 15 years. I'm not sure this was ever fun - when I was in automobile competition, it was sort of part of the pursuit. Today, I enjoy it much less - but I still feel I can do most automotive diagnostics and repair better than any mechanic I could hope to find. Doing It Yourself has risks - and you must suffer a severe lack of information and resources. But if you're reading this, you probably accept these truths.
  • I figured that I'd save about $1000 for each large step I was willing to take. One for pulling/installing the engine; one if I did the engine disassembly/reassembly. I figured I'd still be in for the remaining odd $800 for parts and machine work. I rebuilt the engine in my '73 Porsche 914 autocross vehicle fifteen years ago, but that was with available tutelage from a certified Porsche mechanic. I'd worry quite a bit about those inevitable "forgotten" steps if I did an engine unsupervised.
  • After several months of research, I discovered that two other personal acquaintances who also had 1988 Chrysler minivans with the Mitsubishi 3.0 liter V-6, with very similar symptoms. One of them hired a garage to replace their valve stem seals, and claimed that the oil consumption was cured. Most compelling, I found a Web page detailing this very job for this very engine within 10 minutes of surfing. As much as anything, I was convinced that just replacing the valve stem seals was the Way To Go.
  • This job took me four days. If I'd had all the information I'm including here, it would've taken me two. Today I could do it in one, maybe as quickly as eight hours. But you couldn't pay me enough to do it for money. I'm a freelancer, so I do justify home auto repair as money in our pocket.

About this Document

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  • I started this as notes to myself, after the job was done. I'm writing this from memory, so don't use it as a literal procedural text. I can't guarantee completeness. If something is unclear, please email me at ellsworthc@aol.com. If you obtain the other manuals listed below, I hope this can fill in their omissions. I spent many hours over several months in research and contemplation on this project. I recommend you make a similar commitment.
  • I really wanted to spare someone else any grief that I could by passing along my experience. For many years, I've wanted to be able to share this kind of information with others. Today's public popularity of the Internet provides a vehicle for that sharing.

Reference Materials

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  • I used Haynes (Part Number 1231) and Chrysler factory manuals (P/N 31-370-8005 and 31-370-8006,) and an account by Keith Vickers of an in-vehicle valve stem seal replacement for a Mitsubishi 3.0 liter minivan found on the Web at http://www.allpar.com/fix/3fix.html. The Haynes manual, since it's targeted at DIYers, actually details the process of doing valve stem seal replacement with the engine still in the vehicle. However, it refers the reader to a section of the manual for the 2.2 liter four-cylinder variant of the minivan. The Chrysler manuals don't mention the in-vehicle seal replacement operation.
  • Some of this reference info was actually bad - at least incomplete. Which is why I'm posting this document.

Special Tools I Used for the Job

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  • K-D (In-vehicle) Valve Spring Compressor - Part# 3271; actually a repackaged "E-Z Squeeze #2995" compressor, also resold by a couple of other companies - the K-D 3271 came with an interchangeable longer "arm" for longer springs - which I thought was worth having around for $5 more; $40
    • The K-D was the _shortest overall_ compressor of five in-vehicle compressors available at the tool store I shopped.
  • Nylon Strap Wrench (almost didn't work - had to spray Vibration Damper and wrench strap with 3M 77 Adhesive Spray - see text below); $27
  • A 3/8" drive inch-pound torque wrench (for rocker shaft bolts)
  • A 1/2" drive foot-pound torque wrench
  • 1" long 3/8" drive extension - it would have been nearly impossible to remove the power steering pump bolts without it (inserted with a 15mm socket through the holes thoughtfully made into the pulley) because of clearance problems
  • 22mm 1/2" drive socket (for turning the engine)
  • Air compressor to hold valves closed during valve spring removal and valve stem seal installation
    • must produce at least 100 psi, but doesn't need a lot of flow
  • Spark Plug Adaptor for pressurizing cylinders
    • get one which incorporates a short hose - you'll have problems reaching the holes otherwise
    • many cylinder compression test kits incorporate the very part you need - with spark plug threads at one end, and a male quick-connect air fitting at the other; this is what I used
  • I built a body board to lie on to work on the rear cylinders. At the rear, it was supported at the height of the radiator support - the front simply rested on the radiator support and overhung the engine as needed. A foam pad kept my chest from aching. It was worth it. The few times that I worked on the rear cylinders without the board, my legs and back complained. The board also served nicely as a work surface when I wasn't using it as a body board - I'd just slide it over toward the battery end of the compartment. I used a 1" x 12", about five feet long, and built a wooden structure on the top of a two-foot ladder to match the radiator support height.

Parts Required

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  • Valve Stem Seals: Chrysler P/N MD197467* - $3.85 each [12 reqd]
    • *the parts fellow at the Dodge dealer where I shop knocked them down to this price from a quoted $4.62 each
  • Rocker Cover Gaskets: P/N MD120091* - $12.00 each [2 reqd]
  • Timing Belt**: P/N MD100679 - $45.00 (optional)
    • **This isn't necessary for the task, but because of complications, I had to get this deep into the engine, so it was just practical to replace the belt.
    • *I think the "MD" in the part numbers must be Mitsubishi Diamond
  • Intake Manifold Gaskets - $21.00 (intake and exhaust)
    • I ended up buying a set of intake/exhaust manifold gaskets at a Pep Boys. I didn't really want the exhaust gaskets - when the counter guy asked if I wanted "the set," I was thinking of the gasket for the intake plenum - which I didn't end up getting at all. I never used the exhaust gaskets.
    • Permatex High Temp RTV #101 gasket material
      • It's necessary in installing the valve cover gaskets and sealing the cam end caps.

Procedures

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  1. Checking for Fallen Guides
    • Of all the references I used, only Keith Vickers' Web account suggested the possibility that in some cases, the valve guides themselves may have slipped down into the head. In these cases, the seals bottom on the head rather than seating on the guides. Apparently this condition necessitates removal of the head. Keith Vickers suggested inspecting all the guides before beginning the operation, because it'd be pointless to continue in this condition. The front head is fairly easy to inspect: just pull the hose off the PCV valve, pull the plug wires from the harness and loosen the valve cover's two 12mm bolts. Removing the rear valve cover requires removal of the alternator, and it's awkward to work in the back of the engine compartment over the manifold/intake plenum. Thankfully, our valve guides seemed perfectly normal.
    • Once you've determined that your valve guides haven't slipped down into your head(s,) you can begin the operation.
  2. Preparing for Cylinder Head Access
    • Pull the air conditioner belt andthe serpentine belt.
    • Pull the air cleaner assembly. It's attached to the rear head with two bolts through steel straps.
    • Pull the alternator. I suppose you could actually leave it connected to its harness and rest it out of the way near the brake master cylinder. I completely disconnected it. It's held in place by a pivot bolt and nut which is very visible, and another anchor bolt toward the firewall end of the alternator, head towards the passenger front wheel. I did not remove the alternator bracket - it didn't create an interference problem that I noticed.
  3. Removing Intake Plenum and Manifold
    • I'd say that it's necessary to remove the intake plenum and manifold. Even if you found a really short spring compressor which fit between the intake valves and the intake runners, the ease of access to the rear head without the intake parts is worth the effort. Furthermore, the sludge I found in our EGR plumbing was also inside the intake plenum where the EGR pipe hooked in, so it'd be easier to clean that out off-vehicle. Here's what I recall of removing the intake:
      • This necessitated the removal of several vacuum hoses. I didn't have to label anything. Sizes of hoses and unique angles were adequate. I also had to pull several sensor connectors - no problems there. Throttle and cruise control cables had to come off the throttle body bellcrank. Then I removed the throttle cable bracket from the intake plenum. At the driver's end, toward the rear of the plenum, the EGR pipe is a 5/8" O.D. steel pipe which connects to a flange at the plenum and another flange at the EGR valve itself. The plenum came off with a little sideward tap from a hammer and a block of wood. Now the plenum came free of the car.
    • Before pulling the intake manifold off, I pulled the injector harness connector at the rear of the intake manifold. I chose not to disconnect the fuel lines from the injector rails, or to remove the rails or injectors from the manifold. This spared me from depressurizing the fuel system. After removing the nuts and bolts from the manifold, I tapped downward on the top surfaces of the manifold with a rubber mallet. The manifold came free with a couple of taps. The manifold-to-head gasket did tear in a couple of places, but I'd planned on buying a new gasket anyway. (Don't expect to find a manifold-to-intake plenum gasket at a non-factory place. I didn't actually try, but I wouldn't count on it. Ours survived intact.) I gently folded the manifold on its three fuel system hoses backward so that it rested upside down on a pad over the passenger fender.
  4. Removing Valve Covers and Rocker Assemblies
    • Now that the intake's out of the way, you can pull the valve cover(s) (if you didn't already have them off for the guide inspection.)
      • *NOTE: Remember to stuff rags into the oil return passages cast into the heads, to prevent small parts from dropping through during the following operations.
      • *NOTE: When removing the rocker shaft assemblies, it is likely that one or more of the hydraulic lash adjusters will fall out of the rocker arms. These 7/16" diameter, 3/4" long steel lozenges are recessed into the valve end of the rocker arms, and are only retained by oil viscosity. When they fall, the adjusters are easily retrieved from beneath the cam (the typical place they'll fall) or other cavity with a magnetic parts retriever. Upon reinstallation, dip them into grease to stick them in the rockers during handling. Keith Vickers' Web account suggests securing the adjusters to the rocker arms with wire twist ties. Would've been a pretty good idea, if I'd remembered.
    • Getting the rocker shaft assemblies on and off was a pain. Because some of the valves and rockers are open and thus under compression, the rocker shaft assemblybolts must be removed a quarter turn at a time. Each of the eight bolts takes many of these quarter turns to remove. Because of my own errors (detailed later) I ended up removing and installing the rocker assemblies some five times (twice in front, thrice on the rear head.) I made the mistake of following a manual's instructions and removed all the bolts before removing the cam assembly. Mistake. The bolts should stay in the assembly during removal, temporary storage, and installation. Otherwise, the springs between the rocker arms will push the cam bearing bosses and rocker arms off the rocker shafts. You'll be faced with many separate pieces, which the factory manual points out must be reassembled in the same order.
    • Place the removed rocker assemblies on a clean surface (a sheet of newspaper will soak up some of the oil which will drain from the assembly.) If you can set them on their sides, you might avoid having either the bolts or adjuster fall out. It proved useful to go ahead and stick the adjusters in the rockers with grease to keep them in place while they're set aside.
    • Carefully remove the two rearmost bolts (furthest from the pulley) and the associated cam bearing cap from the rocker assembly. The endmost springs and rocker arms will threaten to spring off, so be advised. Now reinstall the cap on the head. Without it, the free end of the cam can be levered into the air when the engine is turned, possibly slipping off the pulley and resulting in loss of crank-to-cam synchronization. I should know - this happened to me! (more about that later)
  5. Compressing/Removing the Valve Springs
    • I did the front valve stem seals first, because they were easier, and I hoped to learn some technique before proceeding to the awkward rear head.
      • I'd intended to use a technique for holding the valves in place I read in the Haynes manual - stuffing the cylinder with nylon rope instead of using compressed air. If I could have done that, it would've saved me some grief - more about that later. As it turned out, I couldn't get access to the spark plug holes to stuff the rope. Because of a sheet metal heat shield between the exhaust manifold and the spark plugs, I couldn't get my fingers within 4 inches of a plug hole. Pushing a rope across a four inch gap to stuff a cylinder is less than practical. So I went with the traditional method of using compressed air.
      • (*NOTE: because of the 4 inch access problem, you'll want to use a spark plug/air compressor device that uses a piece of flexible hose. It'd be really difficult to use some of the spark plug/air adapters which are solid metal)
    • The preferred technique for pressurizing the cylinders is this:
      • rotate the engine by hand to TDC for the current cylinder; this will require either using a probe in spark plug hole or using the distributor position (provided the distributor hasn't been removed; now rotate the engine slightly past TDC, so that it's on the downward part of a stroke; then secure the ratchet on the crank so that it prevents rotation of the engine in the forward direction (clockwise as viewed from the pulley end); if the ratchet handle is long enough, you can rest/clamp it on the passenger-side halfshaft
      • *NOTE: the reason for doing this step is to provide some insurance that the valve won't drop completely into the head in case of accident or malpractice - I don't actually know that it'll keep the valve from falling past the end of the guide - the consequence of that occurring is removal of the cylinder head; which would be BAD
    • Here's where a semi-disaster occurred:
      • I thought I realized at this point why one account I'd read didn't worry about keeping the engine from turning when pressurizing the cylinders: since the rockers are removed from the head, it wouldn't seem to matter whether the engine was at TDC for that cylinder or not. The valves will always be closed, in any crank position.
      • However, I'd completely missed the argument that keeping the current piston near TDC might save a valve from falling through, so I chose to let the engine turn. I was very lucky that I dropped no valves. You probably shouldn't take the same risk.
      • The bigger problem was the unsupported cam problem, mentioned at the end of "Removing Valve Covers and Rocker Assemblies," above: the cam bearing caps are part of the rocker shaft assemblies recently removed. When the rocker shaft assemblies are out of a head, the cams are merely resting on the lower bearing surfaces and a seal around the shaft between the cam pulleys and the inside of the head. Every time I connected the compressor air supply to the spark plug adapter (without concerning myself with the current cylinder's position,) the engine would spin a partial turn until that piston was at BDC. A couple of times, the non-pulley end of the cam violently lurched two or three inches up off the head, levering itself on the front seal. This was really distressing. On the front head, I was so disturbed by this that I removed the top cam bearing cap from the end of the rocker shaft assembly(this was before I figured out that I could leave all the bolts in the rocker assembly) and bolted it in place at the rear end of the cam. (In fact, Keith Vickers did suggest this very procedure, which I'd forgotten by time I was working on the engine. Just goes to show that I shouldn't trust my memory. Perhaps yours serves you better.) Later, I would attribute losing a couple of teeth's worth of cam timing to these incidents. I would eventually reset the cam/crank timing by manually tilting up the rear end of the cam and slipping the belt off the pulley. I don't know what kind of damage these abuses did to the front cam seals.
        • Do this at your own risk: If you're willing to forgo the insurance of leaving the piston at TDC to keep a valve from dropping, or just believe that having the cylinder at TDC wouldn't help anyway, here's a method that would save you from locating TDC and restraining the crank's turning for every cylinder. If you could put a socket and breaker bar on the crank pulley bolt and clamp the breaker bar to something (the halfshaft is convenient in the Caravan) to prevent its turning in either direction, that would work. You would want to wedge something between the inner fender and the breaker bar to make sure it didn't slip off the bolt head. It's critical that you prevent rotation in either direction, since any given piston might be either before or after TDC, and you couldn't predict the direction of rotation.
          • *CAUTION: If the engine does move under 100+psi of air pressure while there is a tool connected to the crank, you could injure yourself or damage part of the vehicle.
        • You could leave this rig in place for the duration of the valve stem seal work, as there's no reason to rotate the engine during the procedure (if you're not trying to catch falling valves.)
        • If you have a manual transmission, you can avoid all these engine-securing procedures, and simply leave the vehicle in gear and set wheel chocks and parking brake.
  6. Compressing Valve Springs and Replacing Seals
    • The K/D compressor worked well. I could only grab a little less than two thirds of the spring, which was a little disappointing at first. Compressing two-thirds of a spring left a little more than 1/4" of clearance. But it proved adequate, requiring a "special technique." Almost none of the top spring retainers released easily from the valve stem keepers. I tried banging on the spring compressor with my hand - this worked on the first intake valve. But the exhaust valve was really stubborn. I could bang so hard that it'd pop the exhaust valve open, even against 100psi from the compressor. The system I eventually worked out was this: stuff a little piece of rag or paper towel on top of the top of the valve, between the arms of the compressor, to catch any keepers that might shoot out when they release (one of mine did, in fact, do this - leading to a prolonged search about the engine compartment - the towel trick was developed at this point.) Then I'd place a small drift somewhere on the top of the retainer and tap lightly with a hammer. Eventually the spring assembly would drop to the head, and I'd remove the keepers with a magnet. Now I could slip the spring off the valve.
      • *CAUTION: It's critical at this point that you not lose air pressure from the compressor. Likewise, a hard enough tap on the top of the valve stem might pop it loose, even with air pressure. If you drop the valve into the head, and you haven't left the piston at TDC, it'd be really ugly. Again, I don't know that a piston at TDC would catch the valve high enough to leave the stem accessible. Nor do I know if a valve could be recovered without removing the head.
      • The Haynes manual suggests at this point that you slip a rubber band around the valve stem (small nylon wire tires fit well into the keeper grooves,) so that you can de-pressurize the cylinder and check the valve by hand for straightness and guide condition. If you aren't going to check these, you can just leave the air compressor connected and go on to installing the new seals.
    • The old valve stem seals I removed with a pair of slip-joint pliers. They require a little effort to remove. Be careful: it's easy to slip off, and potentially nick a valve stem. Go slowly and twist the seal back and forth around the guide, with constant upward tension. The seals often release suddenly, so keep your face clear of the pliers (especially while you're bent over the engine working on the rear head.) Now choose a tool to help tap down the new seals. I used a 1/4" drive 1/2" deep socket. It should fit around the narrow part of the stem seal without touching the top of the soft seal, and evenly contact the top of the metal shell. It's important not to damage the narrow part of the seal or its little spring.
      • *CAUTION! It is CRUCIAL that the socket (or whatever tool you use) not touch the top of the valve stem. Test fit your proposed tool on the new seal and on the bare valve stem and guide. You'll be tapping on this with a hammer - if the socket came into contact with the top of the valve stem during the tapping, you might tap the valve into the head, despite the compressed air. That would be BAD.
    • To install the new seal, oil the stems with fresh engine oil, and slide the seal down until it contacts the guide.
      • (One account I read said that the new seals should come with some kind of installation sleeve that slips over the grooves in the valve stem, to prevent damage to the new seals. I received no such sleeves, and only noticed this in print after the job was done [notice a trend here?] For what it's worth, most manuals merely mention oiling the stem before installing the new seal.)
    • Press down as much as you can with your fingers. Now slip the socket carefully over the valve stem until it rests on the seal. Tap on the socket with a rubber mallet until the seal bottoms on the guide.
  7. Valve Spring Reassembly
    • Put a glob of white grease on the keepers during reassembly to stick them in place on the valve stem during reassembly. Use a magnetic retriever whenever possible to keep from dropping parts. Make sure the keepers seat when you uncompress the springs.
  8. Final Reassembly

      I'm going to wimp out and hope that you can figure out most of the reassembly yourself. Here are some notes:

    • Remove the end cam bearing cap from the head and carefully reassemble it with the rest of the rocker shaft assembly. The bolts will hold the endmost rockers, springs and bearing cap in place while you move the assembly back to the head.
    • Put a 3/8" long, 1/16" strip of Permatex High-Temp RTV (oxygen-sensor safe) at the corners where the round seals or bearing caps meet the flat machined surface to which the valve cover seals.
    • Place the rocker shaft assembly on the head, being careful not to knick any cam bearing surfaces. It might take some wiggling to seat the assembly. I felt the gaps between the cam bearing caps and bosses with my fingers to determine whether it was going together symmetrically. Now thread the eight rocker shaft bolts with your fingers until they just contact the cam caps. It's important again to run them down equally to prevent bending or breaking the rocker shafts. It's only important that the bolts progress an even depth into the head, even though the loads on the individual bolts during tightening are very different (because some of the valves will be open.) They'll finally be torqued very lightly, so be gentle with a ratchet as you get close to seating the bolts.
    • Tighten rocker shaft bolts in several steps, to a final torque of 180 inch-pounds. Work from the ends of the shafts toward the middle.


Comments

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  • There's no single timing reference mark on the crank which is easily identifiable as TDC. There are three notches in the multi-v crank pulley (serpentine belt) closest to the front of the engine, but none are distinct. Through experimentation, I determined that one was probably TDC. At that time I thought that there were four notches. The notches apparently serve as references for some sort of "magnetic" diagnostic sensor mentioned in the factory manual. One of them is, I guess, also TDC. I say "I guess," because when I had the whole front of the engine open to replace the timing belt (and find out once and for all where TDC was) that I thought the existing notch was a couple of degrees off when using the actual TDC crank mark (under all the pulleys and vibration damper.) One of the notches also provides the only mark that I've found to reference with a timing light. There is a stamped gauge calibrated in degrees (BTDC) which would indicate that (one of the) notches is the appropriate index. I beat a divot in the multi-v pulley with a centerpunch, so at least I'll be able to find TDC in the future without fishing around in a spark plug hole or taking apart half the engine.
  • NOW, after the fact - here's how to establish Compression TDC (provided the distributor-to-cam-to-crank relationship hasn't been lost):
    • Remove the distributor cap; look inside - *IMPORTANT: the contacts inside don't line up with the sockets for the ignition wires on the outside of the cap; THIS IS CRITICAL: determine which of the inside contacts goes to the number one cylinder (located on the passenger side closest to the firewall); make a mark on top of the uncovered distibutor housing which is directly under the number one contact INSIDE the cap. On our engine, the #1 contact was slightly rearward of pointing at the driver's (left) side of the car.
    • Remove the front (nearest the radiator) cam pulley cover; it takes three 10mm bolts, the bottom one is long; you can now see the reference mark for the cam on the engine-front (pulley end) side of the cam pulley - it's a "v" shaped mark pointing toward a tooth on the pulley - it's probably got a dab of yellowish-white paint on it; there's a reference notch at about 11 o'clock on the stamped steel pulley guard (the rear cam's reference mark is at around 1 o'clock in a cast piece)
    • With the coil wire and battery disconnected, put a 22mm socket on a 2 inch long 1/2" drive extension on a long-handled ratchet (a flex-head works well); set it to turn clockwise; put it on the bolt in the center of the crank pulley (it's much easier to get past the A/C hoses if the top radiator hose is off, but it requires draining some coolant - which is pretty easy in the Caravan, its radiator has a stopcock.)
    • Now turn the engine clockwise (I did this a lot with the spark plugs still in; it's harder to turn, but it's a serious bitch to remove/install the rear plugs); every two revolutions of the engine, the cams and distributor turn once. That is: the crank to cam ratio is 1:2 and the crank to distributor ratio is 1:2. When the cam marks get close to their tell-tales, watch the rear crank pulley for the next notch to come around. When the crank notch lines up under the "0" mark on the degree indicator, the cam indicators are on their tell-tales, and the distributor rotor is pointed directly at the #1 cylinder contact, the engine is at "compression" TDC (there is an exhaust TDC as well, every other engine revolution - where the cam indices are 180 degrees from their reference marks.)
    • If you've lost distributor timing because the engine was moved when the distributor was out of the engine, and you're confident that you have maintained cam-to-crank timing, then you could do the crank and cam marks only and put the distributor in so that its rotor points at the "inside" #1contact.

Notes

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I'm really not sure now if what I thought went wrong at the end of day two ever went wrong. Here's the week:

  • Day 1, Monday 5/6/96: started taking apart engine, discovered that there was much more to disassemble than either the manuals or Internet account suggested, including:
  • The alternator must be removed to allow rear valve cover removal.
  • After seeing five "in-vehicle" valve spring compressors in the store, I can't really imagine what compressor would fit between the intake valves and the underside of the intake manifold runners. I ended up removing the intake plenum and manifold - removing all ancillary connections to the manifold but leaving the injectors installed and the fuel lines connected; this required new intake manifold gaskets and cleaning the old gasket faces; as a result of removing the manifold, I think that rear head access for doing the stem seals was substantially improved. However, I ended up removing/installing the rocker assemblies several times with the manifold re-installed with little difficulty.
    • One of the things you'll have to remove from the intake manifold is the metal pipe connecting the EGR valve to the intake plenum. On our engine, the EGR pipe was nearly plugged with a thick black goo. I suspect that this is engine oil passing out of the exhaust system (which is why you're doing this job) re-ingested through the intake. It took a bit of doing, but I swabbed this pipe out with lacquer thinner on several pieces of rag tied to a piece of cord. I fished a piece of bailing wire through the pipe to thread the cord through.
    • Additionally, the intake plenum, intake manifold, and the inside of the throttle butterfly were coated in black crud. I chose not to pull apart the intake plenum halves - it looked like more of a problem to re-seal the halves than any problem caused by the crud. The inside of the nipple on the intake plenum where the EGR pipe attaches was nearly gooed shut, too. You'll have to pull the throttle body off the intake plenum to fish the hole clean. The intake valves were kinda sooty, too, but I deemed that unnecessarily difficult as well. Suit yourself.

Here's why I had to retime the cam:

  • Doing the actual valve spring seals wasn't too bad, considering the rest of the operation.
  • My most critical mistake was misinterpretation of the distributor diagram and instructions from the factory manual. The diagram illustrates that the contact points inside the distributor cap are not aligned beneath their corresponding plug wire. However, both the contact points and the plug wire connections are numbered. The manual should have labeled the distinction between contact point (spark gap from rotor) and the place where the plug wires plug into the distributor. I must admit, I'd never considered distributor caps that weren't "straight through," from inside to out - and I can't figure out why they've done that here. So even though I'd seen the diagram a number of times, every time I tried to position the ignition rotor "directly beneath the contact for number one cylinder," I was nowhere near correct. Which probably means that I lost at least a whole day's work (or re-work) of the cam timing because I thought I was doing the ignition timing correctly.
  • So I got through the front seals on Day 1, and left the other half and engine reassembly for Day 2.
  • I'm pretty certain that the first time that I fully assembled the engine on the eve of day two, the cam timing was probably off. The starter turned the engine over at what sounded like a much greater speed than normal. And with less strain. I suspect that there were no cylinders compressing at all - both cams out of time. I'm less certain about the retiming I did later that day. It sounded better when I tried to start, but still didn't run. I may in fact have gotten the valve/cam timing right and still didn't know that my ignition timing was wrong.
  • So Day 3 was kinda short, as I was weary and muscle-sore. I spent a couple of hours under the hood, mostly looking for a timing mark on a crank pulley that I'd missed. No such luck. In retrospect, I'd successfully found the correct of three possible notches in the block-most pulley by probing the number one spark plug hole with a coathanger wire and turning the engine by hand. But at that point, I was convinced that there was no actual visible TDC mark, and thought that I was having to depend on my own devices. So I unnecessarily removed: the front engine mount; mounting plate; A/C idler pulley assembly; serpentine idler pulley assembly; and the two bolts mounting the power steering pump to the mounting plate. Not to mention replacing the timing belt - the old one looked flawless. I looked in my in-laws' old service records and found no mention of timing belt work. Perhaps the previous owners had done a replacement.
  • After a couple of hours on Day 3, I decided that I'd take a break for the remainder of the day (Days 1 and 2 were 12-15 hours long.) I decided that the only way to approach the cam timing problem was to take the passenger engine mount parts off and treat it as a timing belt change. I decided that it was sensible to go ahead and put in a new timing belt, even though the old belt appeared healthy - as much as I could see it with the cam gear covers removed. I knew that with both crank pulleys removed and the vibration damper removed, I'd be able to see the crank TDC mark for certain.
  • So on Day 4, I started afresh as a timing belt job. It was a good call, in that I didn't have to look at the cam/rocker assemblies again. It proved a bit tedious, but not as bad as the timing belts had been on our two 2.2 liter Dodge Shelbys.
  • Wednesday evening (Day 3,) I dropped by a friend's house and borrowed his timing light and a two-sided steering wheel puller
  • I began Day 4 by shopping for a tool to hold the crank while breaking loose the 110 ft/lb 22mm bolt holding the pulleys/damper. At a local tool store, I looked for a "chain wrench" as suggested by the Haynes manual. But chain wrenches are plumbing things, and a chain wrench big enough to fit around an 8" diameter has a handle three feet long, weighs around 70 pounds, and costs well over a hundred dollars. I considered getting motorcycle chain and modifying a smaller wrench, but the "smaller" wrenches were still over $60. After much deliberation, I picked an aluminum handled thing with a nylon strap long enough for a foot diameter object for $27. I also picked up a cheesy set of metric six-point 1/2" drive impact sockets. The only 1/2" metric sockets that I owned were 12-point, and I figured this was no time to round off a nut.
  • To get access to the lower front end of the engine, you'll need to remove the right front wheel and the plastic inner fender liner; support the corner of the vehicle securely on jackstand(s) - you'll also need a floor jack to support the engine separately when you remove the engine mount
  • The strap wrench worked, but not initially. In retrospect, it might've been more reliable to buy two imported chain locking pliers (Vise-Grip knock-offs) and link them together to get the overall diameter. They were only $10 each, so it would've been cheaper than the strap wrench. The strap wrench slipped on the smooth outer surface of the vibration damper. Deciding that I couldn't return it at this point (the fabric strap was pretty grimy,) I took a chance: after cleaning the damper's circumference with lacquer thinner, I sprayed both the damper and the inner surface of the strap with 3M 77 Adhesive Spray. After a few minutes of drying, I stuck the strap to the damper, tied the remaining strap to the handle to hold it in place, and laid the handle of strap wrench on the passenger-side halfshaft to hold it. I popped a new 22mm six-point socket on my breaker bar, and went for it. It took some effort, but sure enough, the bolt broke loose. A borrowed steering wheel puller (a two-armed affair) did the trick on pulling the damper.
  • Once the damper was off, the crank TDC mark was indeed visible. (During reassembly, I banged my own punch mark on the multi-v pulley to identify which of the three notches was TDC.) It took a bit of work to remove the parts to access the timing belt:
    • A/C idler pulley assembly*
    • serpentine idler pulley assembly
    • engine mount (after supporting the engine on a floor jack) the bottom nut on the engine mount is awkward to access, and is torqued to around 80 ft/lbs; I've had to remove these on all three of our vehicles, and I always use a swivel-headed 1/2" drive ratchet and a socket and reached under the mount from above If you had a very long 1/2" extension (I don't,) it might be easier from below in the wheelwell
    • A/C compressor*
    • A/C compressor mount* (the A/C compressor mount was pinched against the engine mounting plate, prohibiting removal its removal)
    • engine mounting plate* (and the tricky through-the-pulley 15mm bolts holding the power steering pump to the plate)
    • the lower timing belt cover (plastic)
      • *note: when reinstalling these parts, the bolts for the A/C idler pulley assembly must be at least started before tightening the A/C compressor mount; it might be prudent to tighten the engine mounting plate bolts afterwards, as well
  • The preceding procedure probably wouldn't have been so hard if I'd expected to remove the A/C compressor and mount - they weren't mentioned in manuals. I had a bit of trouble removing the big stamped steel engine mounting plate once it was free - this was remedied by jacking up the engine a little to allow it to clear the mounting boss on the body.

Epilogue

[Table of Contents]

  • This started as just a valve stem seal replacement. It turned into a timing belt change. It was a pretty unpleasant experience, taking far longer and requiring much more effort than I'd hoped.
  • It's only been a matter of days so far, but we've seen no visible smoking from the exhaust. The engine runs smoothly and quietly.
  • Update 3/25/97: 10 months and 20,000 miles later, still no smoke. The Caravan uses around a quart of oil every 3,000 miles - probably unchanged since doing the valve stem seals. Mind you, the rest of the engine has 128,000 miles. I'm pretty happy about that. And as things go, I can't really remember how tough this was to do. I'm only reading now from my own document, while preparing it for Web posting, how much trouble I had. C'est la vie.

Ellsworth Chou's Other (hopefully) Useful Pages

  • Does your 1980's Chrysler run perfectly, but stalls every time you roll to a stop? Perhaps your problem is a defective speed sensor . Take a look.
  • If you own a Power Computing PowerBase 180/200/240 and wish it had one of those handy switched convenience outlets, so that all your peripherals power on and off with the computer, here's my $20 solution!
  • Automobile air conditioning and chloroflourocarbon refrigerants - what R-12 and R-134a are and what it means to the automobile owner. Some findings from my own research.

Contact Info

Questions or comments to Ellsworth Chou at ellsworthc@aol.com.


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