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Heard a tick that increased with rpm range, so i assumed it was lifter. So i pull the driver side head and cyl 7 spark plug had oil all over it, and also the cylinder was more black than the rest. Also it is a small chip missing off of the head of cyl 7. You can see the diff circled in red. What in the world is going on here?
What does the piston look like? Is that missing piece lodged in it somewhere? If so, that would explain the tapping noise.
I'm going to go out on a limb and say that given that you have oil pollution in that cylinder, oil is either getting past the valve seals or the rings. Oil in that cylinder would effectively reduce the octane threshold, so that cylinder would knock from pre-ignition (maybe that was the tapping noise?). Any sharp edge in a cylinder will run the hottest and would be the first cause of pre-ignition, and pre-ignition will quickly destroy that sharp edge. That's why race engines have everything in the combustion chamber smoothed nicely.
That pad has the corner broken off right next to the exhaust valve, which would be the hottest area in the CC, so maybe that caused it?
There's also appears to be some nicks above the intake valve in that photo and the pad seems like it's indented slightly, right below the spark plug. Looks like something small was rattling around in there. Maybe it went out the exhaust? Check your piston carefully. Maybe clean it off with a scotch brite pad and WD40 or brake cleaner so you can get a good look at it.
That cylinder definitely ingested something small. Either it messed up cylinder wall or it bent a valve just enough to not seat well. If I had to guess, I'd say it ingested part if the top ring and that may be where the oil is coming from
Post pics of the cylinder wall and piston top.
While the head is off you can soften all the hard corners of the combustion chamber by hand with some 220 grit sand paper just enough to take off the sharp edge. You will probably lose less than 1 hp. That will reduce the hot spots thus reduce knock, thus reduce timing retard. End result, more power under load.
If you decide to have the head decked and trued or go with a thinner head gasket for more compression, you definitely want to soften those edges
I know, you wanted to know what time it was and I told you how to build a clock. Just throwing info out there for less knowledgeable enthusiasts to learn from.
Power adder looking combustion damage just replace with new piston and new rings inspect the valves on that cylinder make sure are not bend put everything back and you are back in business unless you deem time to forge up.
Power adder looking combustion damage just replace with new piston and new rings inspect the valves on that cylinder make sure are not bend put everything back and you are back in business unless you deem time to forge up.
Finally lookee deep enough into cylinder 7 and found this.....
now i know this is a problem. So what are my next steps ? Swap the piston out and work on the heads call it aday or am i in for a long journey?
Just a note for the future. Don't run cheap gas. Tell the truth. Are you running 87 octane gas. If so, you can see how it really matters which gas you choose. Not saying that's the problem but it is common on cheap gas.
new piston and rings and check the intake and exhaust valves and push rods of that cylinder. Good to go.
Just a note for the future. Don't run cheap gas. Tell the truth. Are you running 87 octane gas. If so, you can see how it really matters which gas you choose. Not saying that's the problem but it is common on cheap gas.
new piston and rings and check the intake and exhaust valves and push rods of that cylinder. Good to go.
Had the car 5 years always put 93 in the tank nothing below
02-20-2017, 09:17 PM
Black cylinder 7?
