1988 Johnson Gt 150 Overheating

[J Harrison]

i have a johnson GT 150 that the overheat alarm went off on, i run it for about 10 minutes at idol and the alarm would sound, there was water coming out the tale tale port but it was not a hard stream, could it be a simple impeller or thermostat, Please Help before i start tearing into stuff.
Thanks Jeff

 

[Mas]

Re: 1988 Johnson Gt 150 Overheating

Unless the intake is plugged with crap, you must drop the LU and inspect water pump. More than likely, you must replace the pump.

You might as well test the thermostat too!

MAS

 

[J Harrison]

Re: 1988 Johnson Gt 150 Overheating

When i tear into it i will know if the empeller is bad or not but how do i check the water pump. and another question where is the thermostat located on the engine.

Thanks

 

[emdsapmgr]

Re: 1988 Johnson Gt 150 Overheating

The thermostats are located at the top of each head, making them easy to replace. If you have good water pressure to the block, those are the first things to check.

 

[tashasdaddy]

Re: 1988 Johnson Gt 150 Overheating

when in question replace the impeller after you go that far. cheap insurance.

 

[Giant angus]

Re: 1988 Johnson Gt 150 Overheating

Earlier this month I had the same issue with my 1989 Johnson 110 hp when I took it out of storage. After a few minutes the overheat alarm would go off. I replaced the thermostats, flushed out the ports, and replaced the water pump. After putting it back together and started it, sure enough it overheated again. After isolating the starboard bank overheating and took the head off to check the water ports I found there had been ring binding and some ring broke off causing blow-back, overheating the cylinder.

If changing the pump and stats doesnt solve the problem, do a compression check, then check the overheating bank cylinders. Hope it works out!