Topic: Melted plug electrode
The car is a 93 Honda Accord with the stock 4 cylinder F22A6 motor.
The spark plugs have 3 races on them, car was running great, and 3 of them look absolutely perfect and brand new.. They are 2 heat ranges colder than stock.
I just checked them this weekend getting ready for the Buttonwillow race, and #3 cylinder:
Electrode completely melted.
I'm guessing it's from the injector being clogged or something and running lean, overheating the cylinder and melting the plug.
2 races ago we did dump a jug of gas in the car that had been previously been used for holding a bunch of old dirty rusty contaminated gas in it, and that almost immediately clogged the fuel filter. We just kept running the car and replacing fuel filters. We went through about 3 or 4 filters that weekend and after. So I guess a tiny contaminate could've clogged the injector during that debacle.
A friend has a shop with an injector cleaner/test bench which can view spray patterns and measure output, so I'm going to test the injectors ASAP
After checking the plugs I adjusted valves and everything was good except one of the exhaust valves on the lean cylinder #3 was tight, .007" compared to all the others at .012"-.014" (spec is .012")
So I think that valve/seat had started to burn along with the plug.
Then I did a leakdown test and got
cylinder
#1 87%
#2 81%
#3 74%
#4 58%
For all cylinders I heard the air in the crankcase which just tells us worn rings BUT for #4 cylinder I heard air in the sparkplug hole of #3 which tells me that there's a head gasket leak between the two. Maybe that's why the plug burned up? I don't know, I've never heard of anything like that.
I then did compression test and got (from memory)
cylinder
#1 175
#2 170
#3 155
#4 140
I'm going to wait on results of the injector test and see if we have a bad one, but I'm thinking it would be a good idea to pull the head and replace the gasket/have the valves cleaned up.
What do you think?
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