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60 HP Mercury OB overheats sometimes

P

pres trower

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" I have installed a new impel

" I have installed a new impeller in lower unit and a thermistat. I flush with fresh water after use, but it will stop pumping sometimes just riding along other times after tilting up for shallow water running.... need some help please "
 
"Pres,

Do you know the year


"Pres,

Do you know the year of manufacture, or the model or serial numbers of the motor? These would help a great deal.

You say that it stops pumping. How did you determine this?

"
 
" It is a 1991 model, water s

" It is a 1991 model, water stops flowing from the little pee hole at back of engine and steam rolls from the back, the alarm does not work. Also the engine gets too hot to touch. Once it cools down then it will start to pump again. "
 
"Pres, remove the thermostat a

"Pres, remove the thermostat assy and leave the cover off. Then start the motor, of course having water hooked up to the lower unit or in the river or such. Start and run the engine, does adequate water come out the hole where the thermostat was?

Daren

"
 
" Daren, Yes, adequate flow i

" Daren, Yes, adequate flow is present with thermostat cover off. This is tricky because of irregularity of stoppage. I plan on trying a new pump wear plate next. Once engine is hot I think pressure will not allow water to flow through the power head. Is this typical of this model? Engine runs nice and I do not want to damage rings,etc. "
 
"Pres,

It sounds like you d


"Pres,

It sounds like you definitely have a cooling problem, and I agree that the water pump should be checked out again.

Check the water passage in the lower unit casing for obstructions. Also, it is important that the water pump plate and housing seal properly against the casing. Use a little gasket sealer to be safe here.

While you have the lower unit off hook up a water hose directly to the water tube where the water pump feeds water. Turn the water on and look for any signs of trouble. Usually I also take a length of hose and hold it in place here and blow through it to see if there is any restriction. With the thermostat removed you should not notice much if any resistance here.

You can run the engine with the water hose hooked up and see if it has the same trouble. Feel for any hot spots which would point to an area that is not cooling properly.

Examine the area where the pump housing meets the water tube. This must seal also or you will lose water pressure.

Let us know what you find out.

"
 
" OK, thnks for the info I wil

" OK, thnks for the info I will work on it tommorrow. sounds like good advise! Also my outboard dealer says that the tattle tail water stream is not strong on these engines as the engines in the past (pre 1990) and is not a good indicator of water flow, is this true? "
 
"Pres,
The water stream just


"Pres,
The water stream just tells you if the pump is working. The stream can be good, but you may not have good circulation throughout the engine, or even a water pump that is 100 percent.

"
 
" When I removed the wear plat

" When I removed the wear plate the underside of the stainless plate had a worn out cruddy looking gasket and corrsion built up between the gasket and lower unit. The top of the wear plate had a deep groove near the shaft hole and a shallow wear groove near the outside. I cleaned the corrsion off the lower unit then reinstalled a new plate and gaskets and it seems to be working fine. I will need to put it in the water and ride it around for a day for the final test, but the wind has been to high. I will test this week. "
 
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