Recently, experienced my first knocking start up. I believe it is the head gasket. Could anyone tell me if my piston tops look like they have been steam cleaned? Mileage: 130k Replaced EGR valve, spark plugs, Intake manifold and cooler at 110k. https://photos.app.goo.gl/h7hLkyJxZBvcQHe66 Sorry for the google photos link. I am having trouble uploading pictures to Priuschat.
Are the pistons numbers 1 through 3, top row from left to right, and number 4 in second row? Addendum: Actually the second row pic looks to be same as left end of top row, albeit with enhanced contrast??
Yup your correct pistons 1-3 are top row and 4 is on the bottom. Thanks for catching that, I corrected my mistake.
I don't think in the early stages of the failure you have enough water coming in to clean up the piston crowns like you would see with a big leak That's how we used to break up carbon off the piston tops and the valves and what not in the old days by running water through the system or a vapor and could see sometimes golf ball size pieces of carbon and black stuff hitting your garage door
To answer your question, yes you've got moisture leaking into your combustion chamber. Normally, your piston tops should be black, not clean, like your pictures.
They’re quite uniform though. Often with 3rd Gen head gasket failure, 2 through 4 are really sooty, and 1 significantly cleaner. Early stage?
I agree! I was expecting piston 1 too be cleaner then 2-4. I am torn now if I should take a chance and see if the knocking gets worst or should I go ahead and change out the head gasket.
You could try pressurizing the coolant system with the boroscope in there, look for coolant tears. The Car Care Nut has a video on this. Does your boroscope have a reverse viewing lens you can flip too? So you can look back up at the seam between block and head. If no tears, cross fingers and clean EGR/intake?
