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1985 Mercury 90HP runs hot and fouling plugs

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nautidawg

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My stepson has a 1985 Merc 90H

My stepson has a 1985 Merc 90HP that we got running this weekend after a 2 year downtime. Everything seemed OK as far as performance goes but then I noticed the water coming from the 'pee' hole was extremely warm/hot. It also dropped in power by about 30% after a few minutes running. Inspection of the plugs showed fouling. Any suggestions?
 
Change the impeller - good cha

Change the impeller - good chance it has dry rotted from sitting. Also new plugs and lower gear oil sure wouldn't hurt either...
 
"Thanks Graham,I agree on the

"Thanks Graham,I agree on the impeller change, although there is good water pressure coming from the pee hole and I am sure new gear oil would be welcomed. We did install new plugs before this trip so they should not be a problem. One question, does the water from the pee hole on this year model come from the block water jackets or is it split off from the input hose off the impeller? In other words, is it a direct indication that the block is getting water?"
 
"Robb, it's at the end of

"Robb, it's at the end of the line, after going through the channels, jackets and past the thermostat - kinda last stop before heading down the exhaust housing - so indicates that the water has made it through the engine like it should..."
 
"is it a direct indication, bu

"is it a direct indication, but you can't eyeball how much older Merc's. This is a 6 cylinder so there is no stat/poppit in the system. The PSI gauge should be reading a steady 7-9 PSI at speed. The best eyeball I can give you is by what is blowing out of the surface nostrils down in front. Is should be bailing out of there."
 
"Robb, the water exiting the

"Robb, the water exiting the telltale should be no more than lukewarm, when the motor is running at idle on the flusher device. Any warmer that that indicates a problem."
 
"Thanks all. I replaced the im

"Thanks all. I replaced the impeller this weekend, which definitely cured the heat issue. Still not running at peak performance though. Runs smooth, but not obtaining full power. Probably 2/3rds there but not 100%."
 
"So a compression test is in o

"So a compression test is in order , to evaluate engine condition.Also if you were to have one blocked carburetor jet, then 2 cylinders would not get fuel AND OIL. So it is important to find the problem before running it again."
 
Thanks. I will perform a compr

Thanks. I will perform a compression check. I also plan to remove and clean the carbs. Stay tuned....
 
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