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Discussion Starter · #1 ·
When I was replacing my timing chain and had the valve covers off, I noticed a distinct difference between the oil residue on the spark plug wells between left and right cylinder heads. In general, the right (passenger) side looked like the oil had coated more. Everything looks more brown. Left (driver) side looks way cleaner, and I didn’t wipe down the spark tube wells or camshaft bearing caps.

4519175


What does one make of that? Faulty engine design they may contribute to oil starvation or nothing to be concerned about?
 

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Having recently replaced all my rockers on split occasions. I had plenty of oil on both sides. No discoloration of the spark plug tubes.

IceColeNH on an Android Smaht Fone using Tapatalk.
 

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Discussion Starter · #4 ·
It looks like the left side ran hotter. Air in the cooling system?
I suppose that’s a possibility as I replaced the thermostat housing a long time ago. I hope it didn’t warp the head.

Having recently replaced all my rockers on split occasions. I had plenty of oil on both sides. No discoloration of the spark plug tubes.
Strange. Wouldn’t it be normal to actually see the oil residue?
 

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I changed my father in law’s head gaskets once in his minters sport. That thing was clean enough to eat off and it had over 200k miles on it. He would baby the engine and do oil changes before the schedule said to. I think that’s why his was so clean.

I think some residue would be normal, but I am wondering as well whether your situation is normal. What’s on that side of the motor? Ever have any odd sounds?
 

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Modern oils should leave almost no residue at all unless the engine got very hot. If I had to guess I would bet you that the PCV valve was going bad and the residue you are seeing is from those gas sitting in the valve cover.
 

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Discussion Starter · #7 ·
I changed my father in law’s head gaskets once in his minters sport. That thing was clean enough to eat off and it had over 200k miles on it. He would baby the engine and do oil changes before the schedule said to. I think that’s why his was so clean.

I think some residue would be normal, but I am wondering as well whether your situation is normal. What’s on that side of the motor? Ever have any odd sounds?
I do oil changes every time the engine oil life indicator hits 50%, which — when I look at my maintenance log — is about every 4000-miles. Using Mobil 1 5W-30. PCV was replaced at 80,000 miles.

Never heard any unusual noises (the rocker arm noise, in particular). This engine is very well-maintained; I’ve done virtually all the maintenance excluding two recalls (air bag and ECM reflash by the dealer).

So, based on the responses, it seems the passenger (right) side looks abnormal compared to the driver (left) side, right?
 

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That is perplexing to say the least. I’m guessing there is no signs of unusual wear that you can see. The only thing I can think of is either starvation on the drivers side (maybe a blockage somewhere in the oil passages) or too much heat in the passenger side. If you have a mechanic buddy that you can send the pics too they might be able to help. I hope you get this figured out, and that it doesn’t turn out to be anything bad!
 

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I do oil changes every time the engine oil life indicator hits 50%, which — when I look at my maintenance log — is about every 4000-miles. Using Mobil 1 5W-30. PCV was replaced at 80,000 miles.

Never heard any unusual noises (the rocker arm noise, in particular). This engine is very well-maintained; I’ve done virtually all the maintenance excluding two recalls (air bag and ECM reflash by the dealer).

So, based on the responses, it seems the passenger (right) side looks abnormal compared to the driver (left) side, right?
Hi H3br3wHamm3r,
Please feel free to contact us via private message if you need any assistance regarding your open recalls.

Rob
Jeep Cares
 

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That looks like burnt, over heated oil, baked on. I would check for a oil flow restricken (maybe drain back restricken}, coolant flow restriction, or high exhaust back pressure on that bank. That has the look of oil that has never been changed, but we know that is not the case. So more research is definitely needed.
 
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Discussion Starter · #14 ·
I just came back from store and measured cylinder head temp using IR thermometer, and both measured within 5 degrees or less of each other. Around 212 deg. F, which is to be expected. So, I am thinking that there may have been air pocket in cylinder head (as suggested by Bob Sanders) after I had replaced thermostat housing a long, long time ago. And, I recently drained and re-filled coolant using Snap-On vacuum cooling system filler after replacing timing chain, so hopefully that solved that issue and there wasn’t any permanent deformity of the cylinder head caused by that air bubble. But, it would not hurt to start saving for a new engine. I guess time will tell. Thank you everyone for the insights.
 

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Certainly not. I've bought the vehicle new and never had head replaced.


If you are experiencing timing chain wear there have been known instances of what you suspected, a lack of oil circulation to one particular head causing tje damage or wear. The only 3.6 engines that I have seen need a timing chain typically have oil supply issues of some sort. Hard to say what is causing it because the engine is normally too far gone to even bother spending the time or money to figure it out.

Keep an eye on your oil, maybe even have an oil sample sent off to be evaluated for the presence of metal particulates. Take the sample from the first bit of oil out of the drain plug while doing an oil change.
 

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Discussion Starter · #16 ·
If you are experiencing timing chain wear there have been known instances of what you suspected, a lack of oil circulation to one particular head causing tje damage or wear. The only 3.6 engines that I have seen need a timing chain typically have oil supply issues of some sort. Hard to say what is causing it because the engine is normally too far gone to even bother spending the time or money to figure it out.

Keep an eye on your oil, maybe even have an oil sample sent off to be evaluated for the presence of metal particulates. Take the sample from the first bit of oil out of the drain plug while doing an oil change.
No timing chain wear. That’s a long story, but timing chain was and is fine.
 

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Again unless there was an excessive heat problem I would bet on a faulty PCV valve.
 

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Again unless there was an excessive heat problem I would bet on a faulty PCV valve.
Or a properly operating PCV system. If all the engine vapors are being pulled through the PCV valve in that valve cover it may be normal. If there was no wear on the cams, rockers, or timing chain it seems like a non-issue to me.
 

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Discussion Starter · #19 ·
Or a properly operating PCV system. If all the engine vapors are being pulled through the PCV valve in that valve cover it may be normal. If there was no wear on the cams, rockers, or timing chain it seems like a non-issue to me.
Interesting theory. Never thought of that. I don’t know if there would be enough oil vapors to actually do what’s pictured.

Also, there’s another hose on the driver’s side cylinder head. Just no PCV valve. And the other end of that hose (“make-up air hose”) leads into the air filter box. Why wouldn’t there be any similar signs (oil residue) on the driver’s side cylinder head? I am pretty sure that hose is pulling blow by just like the PCV hose.
 

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Discussion Starter · #20 ·
Again unless there was an excessive heat problem I would bet on a faulty PCV valve.
Because I honestly can’t say — I’m just going to hope that’s it. Do you think that if it was hot enough to do that, then the cylinder head would certainly be warped? Or only maybe?
 
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