4 Stroke EFI thermostat

eleach

Recruit
Joined
Oct 27, 2019
Messages
3
Have a 2002 J50Pl4ST Johnson 4 Stroke EFI.

I had overheat signal go off when in idle for a period. I may not have had the trim down enough or I did find a bit of small rock and some sand in the pee-hole during winterizing.

Odd thing is even after clearing the pee-hole of a bit of sand, I was still eventually getting an overheat alarm in idle with muffs on.

I decided to put the motor in a big bucket of water to test if the water pump was working. I pulled the hose that feeds back to the prop off the thermostat. When I started the motor flat out cold, I was instantly getting water to pump out of the thermostat. So my concern of a bad impeller seems to be ruled out, yet I didn’t think it should instantly eject water from the thermostat either. It never got warm at all from there or the pee-hole.

The motor did run a bit harder at first then idled down in about 30 seconds.

I’m pretty mechanically savvy, though I definitely am not an outboard motor expert. Can anyone please direct me on what I should be checking or doing.

I know you don’t want it overheating, and I also noticed that running a motor completely cold is not good either.

Thanks,

Eric
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,896
Install a new impeller now.------Picked up one of those motors a few years ago for parts.-----Severely overheated to the point of melting plastic parts on the timing chain tensioner.-----
 

eleach

Recruit
Joined
Oct 27, 2019
Messages
3
Do you really think it’s impeller?
On muffs I get a pee stream, but nothing from thermostat. In a bucket I get both.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,896
I guess you can think and do what you like.-----On muffs you really are not testing your pump.-----In fact it is NOT working as a pump.
 

eleach

Recruit
Joined
Oct 27, 2019
Messages
3
I’m definitely not trying to undermine your evaluation. I can follow a service manual and use a wrench.

I will definitely admit that I’m a fair bit ignorant on how the guts of an outboard work. I was only trying to place some clarification on what happened with one and what happened with the other setup.

It’s going up for the winter. If you say impeller ( which I thought of as the “pump” ), then it’s going to get a new one in spring. Do you think the thermostat is bad as well? Seeing I get flow as soon as I turn over motor even though the motor is stone cold.
 
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