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Hi there! Here's the deal. I have a 2006 PT Cruiser, Limited Edition, no turbocharger, 2.4L (I think).

A while back, my engine overheated because of a coolant leak and because I wasn't paying nearly enough attention to it. We traced the leak back to the water pump, and I replaced that. The leaking stopped, but the overheating didn't. After a few months, I finally got it into a shop and they immediately found coolant in the oil. I don't know how long it was there.

Point is, they told me it was definitely a blown head gasket and possibly a cracked cylinder head. I've now pulled off the head. The gasket doesn't look blown or cracked at all in any place. It doesn't look great, and it probably is the original one from 2006, but it doesn't appear to be the problem.

As for the head, it was pretty bad too, but doesn't look like it has any hairline cracks. I've checked it with a straightedge and it isn't warped. There was one set of intake valves just covered with some gross white deposits on the outside and black deposits on the inside. (Before any overheating problems, that cylinder had a useless spark plug. I assume the deposits are from then.) The deposits were so thick, I guess they might have been preventing the intake valves from completely sealing, but I don't know if that would explain anything.

So, the gasket looks good and the head looks good. I don't want to put it all back together until I know I've solved the problem. Is there any other explanation for it? From scouring the Internet, I've thought about maybe the timing cover? The intake valves? Heaven forbid, the engine block?

Thanks for any help you can offer!
 

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Carboned up intake valves most likely is from a spark plug not firing, injector stuck open and dumping fuel and cooking it on the intake valves, things like that. Do you have any pictures you could show, this one sounds pretty interesting to say the least.

Now, the intake does not have any liquid that goes through it so sucking fluid into the engine that way isn't possible. The head gasket can look good or bad without the results of its looks. Overheating makes the aluminum head expand and then compresses the head gasket and from there allows compression into the water jacket, from there it may look good for a while, but there are also oil drain back holes from the head to the block, and if the gasket is compressed, could allow fluid to push out to the oil drain back holes, which is most likely how the fluid got into the oil. Since aluminum is softer than cast iron, the gasket could actually smoosh around the cylinder seals and leak there, especially after an overheat (it doesn't take much sometimes).
So check the head and block. I like using a thick piece of glass (it's very flat) that is half inch thick, and ten by four inches, then using 400-600 grit wet/dry sandpaper, run end to end on the gasket surface, looking at the reflection you can tell if there are any high spots/low spots. Then do a 45 degree angle to that pattern and you will see any and all low spots.You should be able to see the fine scratches all the way across the surface. Do the same to the block, stuff paper towels in any holes to reduce contamination the best you can and wipe everything good when done.

As far as sealing of the valves goes, look for a silver ring all the way around the valve and the valve seats, any black or brown spots means leaking. A full ring means it is seating. Also, get the injectors checked to make sure they are flowing properly. With all the sensors and likes on the injected engines, if one is plugged open or closed, you can't tell because the computer calculates fuel/air ratio with the O2 sensor, thus it simply alters the fuel pulse to make it happen, and if one is dumping raw fuel or not enough fuel, it just changes to pulse width of the injectors to compensate. This can make the engine run lean (that one carboned up valve is a telltale sign of excess fuel dumping), making the other three cylinders run lean to compensate, which does equate to overheating possibility.
 

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Another way to check flatness of the cylinder head is to get a metal ruler, verify that its edge is straight and flat (I did this on a granite inspection surface at work, and by shining a light behnd it to see if any leaked under the edge), and then drag the ruler standing straight up on its edge across the mating surface of the head, while shining a light behind it to look for light leaks.
You can also get a sheet of regular 20-lb copy paper, which is 0.004 inches thick (the max spec for flatness for many cylinder heads), and try to drag it between the head and the ruler edge. If it drags without slipping freely, it's 0.004 or less and head is OK.
 

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Discussion Starter #4
Thanks for your quick replies!

dana44, I cleaned them off to check for cracks and stuff. I should have taken pictures first, oops. So you're saying the gasket could look fine, but actually be blown? I checked the valves and they mostly look okay. It's hard to tell with the ones that were super gunked up. If there were spots, I probably cleaned them up when trying to clean the valves.

Bob, I checked the head with a metal straight edge, paper, and flashlight like that and there's really only one spot that seems problematic. It's right between the two middle cylinders, in the very center of the head. That's the only place where the paper slides without dragging. Everywhere else seems to be within the margin of error. The engine block is fine.

Would it be worth it to have the head resurfaced? How much does that usually cost?
 

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When a leak starts out, unless it totally blows out heavily, there could be small markings so faint, they are hard to see if the problem is taken care of, as you seem to be doing, for much damage to be visible. I had an overheat problem with my 74 Barracuda 318, had a super fast/nasty snow storm come in and was stuck in traffic. Somehow, a fan blade bolt worked its way loose and cut a couple radiator tubes a tiny bit. Since it was so cold, it took a bit for me to notice the temp going up on the gauge, and essentially it pegged a bit. Needless to say, permatex fixed the leak temporarily, then, after she cooled down, I started her back up and she seemed fine. Drove 50 miles in frozen weather back home, had a couple days off work, started her, drove her up the hill and onto the highway and she instantly overheated, then the temp went down. The carbon tracking/squishing of the head gaskets would allow compression into the block, push the fluid into the overflow, then the thermostat would open and fluid go back into the engine. After the overheat, I would stop, fill it back up, cap it, and she would make it the 50 miles to work and then back home the same way two days in a row, then I replaced the head gaskets and she was fine after that. It's the pushing the fluid out of the block before the thermostat opens that is the dangerous part, and once it happens, it is difficult to say how long she will hold together before the gasses eat away at the sealing ring enough to allow fluid to enter the cylinder. That's when you can see a problem, but usually there are tiny, hair width black streaks through the sealing ring around or between cylinders, sometimes you don't even see them they are so clean.
Getting a head shaved can be anywhere from $20-50, depending on the business, just make sure the surface is smooth and not rough from the cuts, and tell them to take the minimum off. Too rough and reduce the gasket sealing properly and you can end up with the same problem again.One last thing that may be an issue with those dirty valves would be valve stem seals, but probably not, because having two valves next to each other doing that, and in the same cylinder, would be extremely rare. I say injector issue, as in fuel dripping and evaporating onto the hot intake valves and just coking up (evaporating and ingredients cooking on the back of the valves).
 

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How did they prove that it was coolant in the oil and not the 'mayonnaise' left behind from normal water condensation in the crankcase?
For every 8 gallons of fuel burned, one gallon of water is produced.
A poorly functioning PCV, excessive blowby, short trip/cool weather driving will aggravate condensation formation under the valve cover, oil filler cap, dipstick tube and the cooler, less turbulent areas inside the engine.
I have had customers that were given a 'head gasket' scare, when it simply turned out not to be the case.

Are these intake valve deposits a 'hard white ash' deposit? Was the spark plug tip 'melted' away? There could have been pre-ignition occurring in this cylinder. Prolonged pre-ignition will eventually damage the rings and cause blowby.
The 2.4L head is pretty sturdy and cracking is not common. If this cylinder ran hot, remove the deposits and check it carefully. Does magnaflux crack detection work on aluminum components?
 

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How did they prove that it was coolant in the oil and not the 'mayonnaise' left behind from normal water condensation in the crankcase?
A poorly functioning PCV, excessive blowby, short trip/cool weather driving will aggravate condensation formation under the valve cover, oil filler cap, dipstick tube and the cooler, less turbulent areas inside the engine.
I have had customers that were given a 'head gasket' scare, when it simply turned out not to be the case.

Are these intake valve deposits a 'hard white ash' deposit? Was the spark plug tip 'melted' away? There could have been pre-ignition occurring in this cylinder. Prolonged pre-ignition will eventually damage the rings and cause blowby.
The 2.4L head is pretty sturdy and cracking is not common. If this cylinder ran hot, remove the deposits and check it carefully. Does magnaflux crack detection work on aluminum components?
I don't think magnaflux works on non-magnetic materials. I think in that case, you use Zyglo - a fluorescent dye.
 

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Imperial Crown, they didn't prove it was coolant, but since my coolant had been draining abnormally quick and there was an overheating problem, I assumed they were right. Plus, once I got to the head, it had the white goo pretty much all over. Would normal condensation have caused that?

"Hard white ash" is a perfect way to describe the deposits. The current spark plug is fine, though. The one I replaced a year ago might have been melted, but I just remember it being worn down from use.

Just in case I missed any warping, I think I'm going to have the cylinder head resurfaced. Between that and a new head gasket, there shouldn't be any problems. I might get it checked for cracks too while I'm at the cylinder head servicing place.
 

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Yeah, white **** in the oil, unless you had sucked some water in it from the rain, which is very difficult to do, would be a leaking head gasket or some other cracked location, which is pretty rare actually, so first things first, go with the head gasket, replace the thermostat since that is attached to the head and off right now anyway (alleviate it after filling with fluid), hoses if they are older than 5-6 years (it's apart, why not), and don't forget the overflow hose and a clamp on each end, and correct radiator cap. Probably an extra $100 of insurance knowing it is all wear items and now new, and be done with it.
 

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Okay, here's the progress report. I got the head resurfaced and then put everything back together with the new head gasket. It's all back together now, but it won't start. Lights, heaters, AC, radio, all that stuff works, but it just clicks slowly, about once a second.

I tried jump starting it, but that didn't do anything except make it click a little longer each second. The voltage measures about 10.5V when it's on it's own, and it was about 12V when it was hooked up to the other car.

My guess is that something is just wrong with the cables, or they weren't attached securely, but is there anything that might have happened when I was tearing it down and rebuilding it that would explain this?
 

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Are you saying the battery measures 10.5 volts at rest (not cranking)? If so, it is too weak (not enough voltage) to engage the starter. That's why you're getting a click. A good battery should measure 12.6 volts at rest and about 13.8-14.4 volts when the engine is running.

If you were jump starting it, some times you have to let the battery charge from the other battery for a few minutes before cranking.

I suggest charging the battery and try again. It also would not hurt to clean the battery posts and cable connections with a wire brush and remove any film/corrosion that has built up.
 

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That's right, although now it measures 11.5V when not connected to the engine and about 7-8V when connected. I'm looking for a short somewhere.
 

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That's right, although now it measures 11.5V when not connected to the engine and about 7-8V when connected. I'm looking for a short somewhere.
Is this after charging the battery?
 
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