TROUBLESHOOTING
SERVICE MANUAL NUMBER 23
Spark Plug Analysis
Normal Condition
Few deposits are present and probably will be light tan or gray in color. This plug shows that
plug heat range is compatible with engine, and engine is electrically and mechanically in
good running condition. With proper plug servicing (clean, file and re-gap), this plug can be
reinstalled with good results.
72420
Chipped Insulator
Chipped insulator usually results from careless plug re-gapping. Under certain conditions,
severe detonation also can split insulator firing ends. Replace spark plugs.
72420
Wet Fouling (Oil Deposits)
Plugbecomesshortedbyexcessiveoilenteringcombustionchamber,usuallyinenginewith
many hours of operation. Worn piston rings, cylinder walls, valve guides or valve stem seals
are causes of oil entering combustion chamber. Only engine repairs will permanently relieve
oil wet fouling.
IMPORTANT: New engines or recently overhauled engines may wet foul plugs before
normal oil control is achieved with proper break-in procedures. Such fouled plugs
may be serviced (clean, file and re-gap) and reinstalled.
72420
Page 1C-4
90-861326--1 MARCH 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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Marine readers have rated Mercury MerCruiser GM V8 GM V8 454 CID 7.4L and 502 cid 8.2L Marine Engines Service Manual Number 23 5.0 out of 5.0 based on 1 product reviews. Just need the manual. Wrote review. Can't technically review what I haven't seen yet...