Pulled the plugs as PM and decided to borescope the cylinders out of curiosity. Found this in one of the cylinders (driver side closest to firewall). What is this? Is it coolant (HG failure?). Really hope not. Attaching a few images. Thanks.
What's this in my cylinder (1 Viewer)
- Thread starter rexington14
- Start date
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If you had coolant loss, the piston will be steamed cleaned and looks shiny.
Looks like a bit of oil got baked in. This can happen if your spark plug has backed out a bit and you have leaking valve cover gasket tubes. Similarly it could be caused by a longer term rich condition on that cylinder; usually a coil pack or bad plug.
Did the plug threads have any signs of oil on it? What does the spark plug tip look like? Are the valve cover gaskets and spark plug tube gaskets new?
The DS closest to firewall spark plug is in my experience the plug that has started backing out every time before the others. So something to look at. But not something I would be super concerned about like I would be to see a super shiny piston.
How do the cylinder walls look? Any variance from the others?
Did the plug threads have any signs of oil on it? What does the spark plug tip look like? Are the valve cover gaskets and spark plug tube gaskets new?
The DS closest to firewall spark plug is in my experience the plug that has started backing out every time before the others. So something to look at. But not something I would be super concerned about like I would be to see a super shiny piston.
How do the cylinder walls look? Any variance from the others?
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- Thread starter
- #4
Here are the 4 DS plugs in order. Plug on the left was closest to the front bumper, plug on the right was the closest to firewall.
Here's a shot of the threads from that cylinder's spark plug hole.
Valve cover gasket is original. Don't see any oil leaks externally.
- Thread starter
- #5
I had thought that to be the case as well. Just curious what that residue is then - it almost looks pinkish like dried coolant but then again its a pretty cheap borescope. The other cylinders didn't appear to have this residue when I scoped them, although I didn't bother to crank the engine for the cylinders where the piston was toward the top of the hole.
They all look pretty evenly run to me. Nothing that stands out on the plugs I suppose.
It's interesting that this back DS firewall cylinder seems to be one that people run into these spark plug issues with; including having noticed it being a little looser myself when I go to change mine out and to check torque occasionally.
I don't know whether to tell you it matters or not, but if I could see cylinder cross hatching, etc. I wouldn't worry about it.
It's interesting that this back DS firewall cylinder seems to be one that people run into these spark plug issues with; including having noticed it being a little looser myself when I go to change mine out and to check torque occasionally.
I don't know whether to tell you it matters or not, but if I could see cylinder cross hatching, etc. I wouldn't worry about it.
The #7 piston top looks a bit to clean. Spark plug from cylinder #7, also a bit to clean. But really the pictures aren't great/clear. So making any call difficult. Your #7 is cleaner (or appears so) than one I pictured below. If all your piston top the same, as your #7. Then likely HWY and or some fuel and or intake de-carbonizing done. So your good. But if only #7 piston top clean. I'd do more testing! Test that can be done now, while cold and plugs out. Pressurize coolant system to about 15 to 17 PSI. Then look into #7 cylinder again, for any coolant leakage at head gasket. Also noted any coolant loss, since you've owned and was system low when you bought. Clues!
I did borescope of a cylinder last week. My interest was the cylinder walls. 2 cans of 44k used, ~ 1K miles earlier. Run a lot on HWY. So some de-carbonizing would have taken place. Picture of piston top here not great. But notice the carbon.
I did borescope of a cylinder last week. My interest was the cylinder walls. 2 cans of 44k used, ~ 1K miles earlier. Run a lot on HWY. So some de-carbonizing would have taken place. Picture of piston top here not great. But notice the carbon.
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The 2023/04/20 pictures above. Came from 4.7L where I found the air filter seal curled down. Which I find in 1 in 5 100 series. This one, driven daily on dirt roads. Air pipe the dustiest I'd ever seen. So while check #4 cylinder for loose spark plug and if factory or replacement plug. I decided to scope it.
I just uploaded a video of above borescope inspection. It may give you better look at cylinder & piston top. Which is typical piston top, when some de-carbonizing and HWY driving done in advance of scoping.
I just uploaded a video of above borescope inspection. It may give you better look at cylinder & piston top. Which is typical piston top, when some de-carbonizing and HWY driving done in advance of scoping.
- Thread starter
- #11
Thanks for the info. Here are my borescope shots from some of the other cylinders for comparison (limited to 5 pictures). It seems (to me at least) that all the piston tops look similar to cylinder 7 in the first post, except that cylinder 7 has the strange residue I was concerned about. I believe my borescope is too poor quality. It seems the pressure test is the next step, and/or a better borescope.
FWIW the spark plugs are only ~10k miles old so could be why they are clean
Cylinder 4
Cylinder 6
Cylinder 8
Cylinder 3
Cylinder 5
uHu
Bridgeburner
Looks like the spark plug of that cylinder has some residue in the threads. Also the plug hole threads look a bit dirty/carbonized, like the plug has been loose, but not loose enough to damage the threads.
