cleaning cylinders ????

clay mills

Cadet
Joined
Sep 2, 2002
Messages
9
I have a '84 Mercury 7.5 that seems to be in tip top condition until you look into the cylinders thru the spark plug holes. The engine runs great but tends to foul plugs during short runs. Is there some way I can clean these? (perhaps an engine treatment of some kind) The motor had set up for several years prior to my recieving it. thank you
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: cleaning cylinders ????

There are several decarbonizing products that work in breaking up these deposits.I would recommend doing compression test so that you have a baseline for fouling problem and to determine final outcome of decarbonizing.
 

clay mills

Cadet
Joined
Sep 2, 2002
Messages
9
Re: cleaning cylinders ????

I recently had the engine in the shop for an impeller replacement and was told the compression was fine. I'm looking for a do-it-yourself treatment if that exists. thank you
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: cleaning cylinders ????

I'm sure your dealer has some of these products on shelve.Some you spray into carb inlets or even directly into cylinders and let sit for several hours before running out.If compression checked out fine at dealer I would assume that carbon build-up has not effected ring grooves.If fouling is freqent it is ether due to carb adj.,oil rich mixture,or excessive running at trolling speeds.Did your dealer happen to tell you what the compression readings were after he performed them?As poor compression is also a cause of wet foul plugs.Also, insure that you are using operators manual recommended plug application.
 

BillP

Captain
Joined
Aug 10, 2002
Messages
3,290
Re: cleaning cylinders ????

If the engine is worn and plugs fouling from blow by you may need to up the plug heat range by one. This is normal to do if you idle a lot or run in cold water on small motors without a thermostat. Don't forget to check the plugs often when changing heat ranges to make sure they are right. <br /><br />Make sure your oil type and ratio is correct too.
 
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