help stop the overheat

[f16dcc431]

hi yall i have a 1989 larson all american 170 she has a mercrusier alpha one out drive with the 3.0 inboard i dont know were to start yeterday on the lake she was running hot so i headed into shore and the temp dropped 20 degrees when i was moving. In the driveway i tried to do some trouble shooting, when i diconected the hose from the out drive to the thermostat housing and hooked the water to the stern drive i got water flowing but not a lot. So i hooked the hose to the themostate houseing were the water would go in and started the moter and it ran fine temp did not jump or anthing so being new to boat repair it makes me think its the water pump because when i was on the lake the water pressure from moving ramed water into the engine but is it the waterpump on the engine or in the stern drive kinda need help thanks JOSH

 

[Don S]

Re: help stop the overheat

The raw water pump is in the drive, and the impeller should be replaced every couple of years.
Procedures are in the OEM Service manual #6
http://www-alt.mercurymarine.com/mnetdata/sisdata/srvcovr.pdf

BTW, manual #10 is the one you want for your engine.

 

[Bt Doctur]

Re: help stop the overheat

If you hooked a hose to the housing and did not supply water to the drive, the impeller was damaged when you ran the motor. best to replace impellers every 2 years

 

[f16dcc431]

Re: help stop the overheat

i got a very little watter not alot would the impeller still be broke

 

[Haut Medoc]

Re: help stop the overheat

It can just be worn.....
You will need to disassemble the drive & look....​

 

[f16dcc431]

Re: help stop the overheat

so i pulled apart the stern drive today and you all were right the im peller had 3 missing bades and on on in half i appreicate the help guys i hope this fixes the problem i will go get the new one tomorrow for any one new like i am changing the impeller is easy for the time it took to pull apart i will change it every year

 

[Haut Medoc]

Re: help stop the overheat

Once a year is overkill IMHO.......
You really should try to backflush the cooling system to get those missing vanes out.......​

 

[Bondo]

Re: help stop the overheat

and you all were right the im peller had 3 missing bades and on on in half

Ayuh,......... Now you've got to track down,+ remove All of the missing pieces,......
If you Don't find them,....... They'll come back,+ Haunt you with More Overheating Issues.........
They're Probably somewhere between the Outdrive,+ the T-Stat.........

 

[bagodoughnuts]

Re: help stop the overheat

Good morning gentlemen. I have a couple of questions for you. Brief explanation to my problem, i have twin 350 chevy inboards with an overheating problem. My engine is fully repaired with new block, heads, exhaust manifolds, new raw water shaker pumps and circulating pumps, new thermostats (140) degree, and new sending unit, and temp guage. My pick up is clean, oil cooler is clean. While under load temperature holds at 140 - 160 degrees, my problem is when i back down the throttle to idle my temp skyrockets to 220 - 240 on both engines. i have to slowly bring my throttle to compensate temprature, this is a constant battle. what suggestions do you have? Timing is perfect, new high performace distributor ect. ect. However i dont have a RAW WATER PUMP only shaker pump. Will buying a RAW WATER PUMP solve this problem?

Help wanted please.

 

[Don S]

Re: help stop the overheat

Welcome aboard
Please start a new thread with your question. DO NOT just tack on to the end of someone elses 2 year old thread with your questions.