Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.

Cars by name
Trucks and Jeeps

Engines / Trans
Repairs / Fixes
Tests and Reviews

Disc-O-Tech: brake swaps

Driving the Fiat 500X

2007 Sebring: killing the franchise

2.2 and 2.5 Liter Mopar Engine Repairs

MAP sensor advisory: Dead MAP sensors are the bane of a 2.2/2.5, and one of the most common causes of dead vehicles. We were told some years ago by an anonymous source, “There is service advisory and an available air bleeder valve kit to prevent intermittent operation and premature failure of the MAP sensor. The valve allows a small amount of dry air into the MAP vacuum line to prevent a condensation buildup. It’s a low cost add-on, inquire at the dealer for the part. I used up six MAP sensors before finding out about this - haven't lost one since.”


Ralph Mazeski wrote that his 2.5-liter 1993 Acclaim was backfiring through the throttle body at idle, about once a second, making it virtually undrivable. It happened suddenly on a cold startup with no previous symptoms. No codes were set. Items checked include wires, plugs, coil, timing, vacuum leaks, compression, MAP sensor, TPS, and grounds. Finally, based on a Net tip, Ralph opened the valve cover and found that the rocker arm had fallen off the #4 exhaust valve; it was just laying there, with no obvious signs of damage or wear. The lash adjuster was solid, not spongy; it was a rebuilt head and Ralph believes the problem was excess wear on the valve stem tip. He installed a new rocker and lash adjuster.

Oil changes, belts, CV axle, radiator

On any 2.2/2.5 front wheel drive Chrysler, oil changes are accessible from the top, one only need to slide underneath slightly to remove the drain plug. No need to jack the vehicle up.

Belts on a 2.2/2.5 all have a square tightening spot to put a ratchet.

The CV axle is also relatively easy to replace; remove a wheel, axle nut, 18mm pinch bolt, pry the lower A-arm (control arm) down and pull out the axle. (B10alia added: “What we ended up doing was swinging the stabilizer bar out of the way by disconnecting it at both control arms, but leaving it on the subframe. Because this thing is a huge torsion spring and is connected to both sides, we were prying down against a spring force and the driver's side suspension. It took about 5 extra minutes total to do this, but it probably saved us an hour in trying to come up with a way to get the control arm down. Once the bar is gone, the control arm comes off real easy. This was not mentioned in the FSM.”)

Jeremy Zumwalt noted a fix for consistently breaking C/V joints (2.2/2.5 liter): changing the motor mounts. The motor mounts on the 2.2/2.5 liter engines are often a weak spot.

Disintegration of the vacuum hoses

Over time, the vacuum hoses disintegrate where they go over the engine. One set goes to the vapor canister; this set includes two vacuum check valves. Twin vacuum hoses come from the throttle body, meet, and join before running to the vapor canister relay. We don't know why. Another hose goes from the wastegate to the turbo solenoid which is right next to the vapor canister relay. You can't get the solid pipes used by Chrysler any more, and will probably have to use ordinary vacuum hose (fuel line hose, for the vapor canister line and possibly others) with standard connectors.

Sticking throttle

Tim wrote: The idle air control (IAC) valve in the throttle body can get sticky after a while. The best way to clean that is to remove the throttle body, remove the IAC from the throttle body and clean it and the hole it came out of. You'll need some small Torx bits if it's like mine. Alternately, you may be able to clean it enough to 'get by' simply by spraying some throttle body cleaner at the IAC outlet in the throttle bore. You'll have to open up the throttle blade to see it. After a while, a ring forms in the IAC passage and the plunger can't move by it smoothly, if at all.

Hydrocarbons or running rich

John Auto Tech noted that the 2.2 / 2.5 was "notorious" for charcoal canisters becoming saturated with raw fuel, due to the positioning of the canister below the fuel filler neck. The result is higher hydrocarbon levels and symptoms of running rich (despite the oxygen sensor working correctly).

Belt squeaking

John Auto Tech wrote: "The alternator serpentine belt is known to squeak due to the alternator being out of alignment on the 2.5L engine. To check this (as a possibility) use a small prybar and shift the alternator forward and back on its pivot point and see if the noise goes away. There is a shim available to reposition the alternator in the event that this is the noise."


Wes Grueninger said: Almost all radiators used with nonintercooled 2.2s, carbed, TBI, or T1, are identical in dimension, regardless of body style. They have a 22-1/4"x15-1/4"x1-1/4" 2-row core, 1-7/8x16-3/8 end tanks, a 1 to 1-1/4" inlet and a 1-1/4" to 1-1/2" outlet. This applies to 1981-89 models. N bodies, P bodies, and Dakotas use different radiators. Two bolts and a couple of hoses, and the radiator is out.

Valve cover oil leaks

An engine designer wrote: "We had a problem early on with oil leaking out of firewall side of 2.2/2.5
valve covers after RTV was eliminated in favor of a gasket. The attaching screws were not shortened to compensate for a thinner walled valve cover, which resulted in the screws bottoming out. They 'torqued up' all right, too bad it was against the bottom of the hole instead of the valve cover.........a dab of RTV was still necessary at the inner bend above the bottom boot (near cam cap parting line)."

Tim Mikolay wrote: For some reason on this model, and a GLH I painfully sold, I retorque the spark plugs AND the throttle body gasket bolts at every season change. They work themselves loose like a Harley.

With a new one piece valve cover gasket (first I've ever seen for this engine), a redesigned oil filler cap that doesn't leak and hose clamps on either end of the hose connecting the valve cover to the air filter housing (legendary for oil leakage), oil stays.

"kd5inm" wrote: Today I took the valve cover loose and cleaned everything up and reused the rubber end pieces and used O2 sensor safe red RTV to "make" a gasket for the valve cover. The old gasket was the two paper pieces on back and front and rubber on ends, the rubber was good and it didn't leak from sides, but did leak from backside and frontside of the engine (looking at engine from front of car). I applied a thin coating of RTV on both the valve cover and on the head and then let it get tacky, then I reassembled the valve cover and tightened things snug but not too tight. I ran the engine after everything was buttoned up and no oil leaks so far.

Jeff Silva wrote: I have had a persistent problem with my '86 New Yorker with 2.5 [liter TBI engine]. I bought the 2.2/2.5 valve cover reinforcements [P4286758]from MP, along with the chrome valve cover attaching bolt set [P4286761] and installed them last weekend.

The cost was very reasonable [$40.00 for both CDN] and the items were very easy to install. I did not change the gasket which I probably would have had I been doing this on any day other than a Sunday. In fact, I did not remove the valve cover, just torqued down the hold down screws, just to see if I could get away without a gasket change. The cover reinforcements better distribute the clamping force of the hold down nuts it would seem. In any event, no more leak. The only bummer was the length of time I had to wait for my parts [prepaid] from my local dealer. I put in my order in December and the parts arrived in the latter part of March. And the extra chrome cannot help but make the car go faster, right? [webmaster note: do not over-torque the bolts! use a torque wrench and the specifications given by Chrysler.]

Travis wrote: “I seem to have found shorter bolts to fix that annoying engine leak on the the back of the 2.2 and 2.5 liter engines. I got mine at Advanced Auto Parts: Doorman, Part #980-210. Specs - M6-1.0 X 10mm Class 10.9. A new valve cover gasket set is a good idea, just make sure you get the top of the head and the valve cover very very clean. This may not work if you have a high mileage engine with a lot of blowby from the piston rings, if thats the case you may be better off just buying a rebuilt engine.”

John Nikolich wrote: I am a school bus mechanic who also takes care of driver ed cars. I had a terrible time sealing the 2.5l valve covers until I found Chrysler had a replacement valve cover that uses an O-ring type seal. (It’s one piece unlike the original gasket.) Once I replaced the covers with the updated covers they NEVER so much as seep.

Loud Exhaust Noise

Allpar forum user "chilibowl" wrote that his '84 Reliant 2.2 liter carburetor project car was running smoothly with good compression but emitting a "loud exhaust noise." When looking into it, he noted that an air injection tube/pipe that was probably going to the air pump had rotted out. He noted that there is definitely a disconnected pipe going to the catalytic converter but when putting a thumb on the hole (on converter), there is a little noise reduction.

Forum user "urr" suggested that the donut gasket, which seals the junction between the manifold and the exhaust pipe, is shot. Bob Lincoln suggested that the air injection pipe can be capped off with no ill effects. "The air injection pipe goes form the airbox to the catalytic converter. It has a one-way valve in the middle so that the exhaust suctions in extra air to reduce HC emissions." Lincoln also mentioned that if there is an actual air pump then the connection should be repaired. The silicon hose can be used to connect to the catalytic converter. "If the small pipe at the converter broke off, you can have it welded or get a new converter. "

According to the FAQ:

Chris Zwingli wrote:

  1. If you have to replace a leaking valve cover gasket on the 2.5 with the 4-piece gasket(2 rubber end seals and 2 cork side rail gaskets) do yourself a favor and use the Victor Reinz set for this application. Do not use the FelPro set. The Victor Reinz gasket is about $2 cheaper and actually does a much better job of eliminating oil leaks-I found this out by accident after unsatisfactory results with 2 FelPro sets.
  2. If you find that the spark plugs are rusty, replace them with Champions.
  3. I do not recommend the use of Slick 50 on Chrysler products-it caused slow leaks of the rear main oil seals on both of my vehicles. Fortunately, draining the engine oil and replacing it solved the problem on both cars('90 Dodge Spirit and '96 Plymouth Neon).
  4. If you find oil in the air cleaner housing, suspect a partially plugged PCV system. This can be solved in the 2.5 TBI by using a can of GM Top Engine Cleaner. Just follow the directions on the can.
  5. If you have to replace a leaking heater valve, be careful and compare the old one with the new one if it is aftermarket. Some of the aftermarket valves are taller than the original factory part and will cause interference problems with the air cleaner housing, leading to reinforcing ribs on the air filter housing rubbing through the upper hose between the heater core and heater valve.
  6. While I am on the subject of heater valves, do yourself a favor and cut the old hoses off the heater core inlet and outlet instead of trying to twist them off. Twisting or pulling off the hoses could provoke the heater core into leaking- not a happy prospect.
  7. While I am on the subject of hoses, it is possible to replace the z-shaped molded hose between the intake manifold and the heater valve with plain old 5/8" heater hose-just be sure to let the engine get to full operating temperature after you refill the cooling system. The heat will allow the hose to adapt itself to the new situation with very satisfactory results.
  8. If you replace the transmission fluid and filter on the 3-speed auto trans, make things easier for yourself the next time by using a cork gasket instead of RTV. The cork gaskets work fine if you make sure that the mating surfaces on the transmission housing and pan are clean and free of any old material and that there are no bolt hole dimples in the trans pan.

Rough idle

Some places to fix a rough idle:

Bohdan Bodnar's Notes

I was playing around with my 1986 Le Baron (2.5 liters TBI with a/c) and thought that some of the more technically inclined readers may be interested in my experiences. Here are the problems I was addressing:

  1. On a hot engine, the idle would "randomly" drop abnormally low (but not low enough so as to stall the engine) and would be corrected. During the correction, the idle sometimes overshot what appeared to be the desired idle rpm. This problem has been around for the past few months, but it's been COLD in that garage...
  2. Intermittent engine knock developed in the past two weeks.
  3. Records of fuel efficiency showed a marked decrease in efficiency (in miles/gallon) in the past two weeks.

Now, for the first problem...

 A weird idle problem on a hot engine (or, for that matter, ANY drivability problem under this condition) usually implicates the feedback control system. However, this car had a new oxygen sensor (replaced 13 months ago). As expected, no trouble codes were stored. I connected an oscilloscope to the O2 sensor and let the engine idle.

My opinion was that the sensor's output wasn't "steep" enough (the transition from a high reading to a low reading and v.v. should be FAST -- almost a step response). The reference voltage the computer was feeding the sensor was 438 mV, not the 450 mV I'd expect (but this isn't a big deal -- computer systems put an "error band" around the 450 mV threshold and ignore sensor readings in this band -- this is like trying to operate a digital logic gate in the "forbidden region"). I next decided to check the average a/f mixture.

The easiest way to see what the a/f mixture is is to use an ignition oscilloscope. Since I don't own one, I did the next best thing -- I 'scoped the primary side of the ignition coil. On a well operating engine, here's what I'd expect to see:

  1. Firing line (ignition voltages) about the same for all cylinders -- no more than +/- 20% variation between the highest and lowest. If an ignition oscilloscope was available, I'd expect to see the maximum differences to be less than 3 kV. If the firing line is jumping all over then the a/f mixture is screwed up.
  2. Spark time ("burn time) to be in the range of 0.85 ms to about 2.2 ms. Also, the spark line should be somewhat jagged AND FLAT. A line which rises upward toward the end of the burn period indicates lean misfire. Typical spark time is around 1.6 ms.
  3. Firing line to spark line voltage ratio should be about 4:1.
  4. At least 5 coil oscillations after the spark ceases (some computerized diagnostic gear -- e.g. Sun's "Modular Computer Analyzer" -- look for a minimum of 3 oscillations).

In my case, the firing line to spark line ratio was substantially higher than 4:1. This is attributed to using non-Chrysler ignition wires which have MUCH more resistance than Chrysler's specs (these are Autolite wires). The firing voltages were almost all the same (indeed I couldn't tell the difference between the cylinders). Spark time varied from 1.9 to 2.1 ms and the spark line was almost ruler-flat. Around 10 coil oscillations were present.

This is a classical example of (1) abnormally high secondary resistance (2) perfect ignition coil (by the way, this is a Wells coil -- about a year old) and primary circuit, and, possibly, an engine running rich. Temporarily shorting out one of the cylinders showed that the firing voltage for that cylinder did not change appreciably -- hence, confirmation for the fact that the secondary resistance is too high. Also, the spark voltage did not change appreciably.

2.2 liter engineBased on these observations, I replaced the oxygen sensor. The new sensor's response is much better (closer to a step function). Why did the previous sensor fail? The most probable answer is that the engine blew its head gasket a month after the previous sensor was put it. Silica in the coolant contaminated the sensor and caused its response time to increase. Eventually, the computer would have caught the problem ("eventually" meaning at least a year from now). Now, on to the engine knock problem.

When diagnosing engine knock, I look at two things: fuel quality and EGR operation. Only if these two are eliminated as culprits do I look to see whether a lean a/f mixture exists. Since the idle looked ok in open loop, I discounted fuel quality. I tee-d a vacuum gauge into the EGR valve's vacuum line and, with the engine running, slightly opened the throttle.

With no appreciable engine load, I expected to see about 5" Hg control vacuum. Instead, I measured full ported vacuum. To understand what this means, one has to understand how the EGR system meters exhaust gasses.

The backpressure transducer has two vacuum hoses and a stainless-steel backpressure pipe feeding it. The pipe feeds exhaust gas pressure to the transducer. One of the vacuum ports goes to ported vacuum (or, the EGR solenoid if this is the 2.2 turbo or multipoint injected engine) whereas the other feeds the EGR valve. If the exhaust pressure is high, the transducer opens and allows control vacuum to move the valve's pintle up. This increases EGR. If the exhaust pressure drops, the transducer closes and allows atmospheric pressure to enter the EGR valve and close it. By oscillating back and forth very quickly, the backpressure transducer allows the EGR valve to see a smoothed control signal and thus open only a certain amount. The amplitude of this (pneumatic) signal is a function of engine load, rpm, etc.

Since the transducer was applying full ported vacuum and since the engine didn't bog down when the throttle was slightly opened, the implicated culprit is the EGR valve. I connected a vacuum pump to the valve and pumped up about 15" Hg vacuum. The valve's pintle did not move.

A new valve/transducer assembly will be put in within the next two weeks.

More repairs and maintenance tips

Dan Minick wrote: on any 2.2/2.5 fwd Chrysler, oil changes are accessible from the top, one only need to slide underneath slightly to remove the drain plug. No need to jack the vehicle up. Same with 2.6 engined Mopars, although a little more reach is required to reach the oil filter around the manifolds.

Belts on a 2.2/2.5 all have a square tightening spot to put a ratchet.

CV axle-remove a wheel, axle nut, 18mm pinch bolt, pry the lower A-arm down and pull out the axle.

Wayne Toy wrote: The screws that hold the distributor cover on are type M4X0.7.  I run a tap through these two screw holes every time I remove the screws.

Other pages

See our page on building a PCV oil canister to prevent PCV system oil leaks.

See tuning the 2.2 and 2.5 liter engines

See many more repairs some of which are directly 2.2 / 2.5 related

The minivan that just won’t die

Spotted: the terms for Demon owners

Ram vs “rest of FCA” in JD Power

More Mopar Car
and Truck News