Fouled Plug

bbeep71 said

Only #3 is fouled. The other spark plugs look good. Does the leakdown test check the valve seals or just the valves? Should I just check #3 for compression and leakdown or all of them? For now I bought a hotter plug RN12YC to RN14YC for #3 hoping it helps until the season is over.
Thanks Guys O:)

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It's up to you on how many cylinders you test. I would take the time and do all of them myself. You can then save the results if you have trouble later and need to know where it used to be.

The compression test and leakdown test will let you know if there is any problems with the cylinder sealing; rings, intake and exhaust valves. If you can pass both tests, then you have an engine in good shape. It should put out good power. If you fail the test, then you should fix what is causing the low readings.

The hotter plug may help, but you are just burning the build up off. You should find the root cause of the fouled plug and correct it.