Help! 2000 Johnson 90hp V4 overheating on one side only...

[Boatbuilds]

I have a 2000 Johnson 90hp V4 that I can not fix. I am having overheating issues. One side is running fine at about 103 operating temperatures; the other is running at about 185. I assumed it was a thermostat so I took them both out and checked to see if they were still working. Turns out they were. I then installed them both and am having the same issue. Even if I reverse the thermostats I run into the same issue of the right side running hot. If I take the thermostat out I do not have any overheating issues though. I am at a loss and can't figure it out. It cools fine with the thermostat out but with the thermostat in it will not cool. Please Help!

 

[Crosbyman]

pulling the cyl head to inspect water jackets isn't al that comlicated and only costs is a new gasket.

is this a sudden problem , evolving problem over time. ?

when was the impeller serviced last ? any chunks missing ?
salty or fresh water engine ?

mdl# ???

 

[Boatbuilds]

pulling the cyl head to inspect water jackets isn't al that comlicated and only costs is a new gasket.

is this a sudden problem , evolving problem over time. ?

when was the impeller serviced last ? any chunks missing ?
salty or fresh water engine ?

mdl# ???

The motor is run in salt and fresh but always flushed for at least two minutes in fresh water after each trip. This is a sudden problem after I had the motor serviced for a new impeller and a carb tune it happened the very next trip. The previous impeller was all intact. engine number is J90PLSSE. I don't get how a jacket could be clogged if the motor doesn't overheat when the thermostat is removed.

 

[saltchuckmatt]

Try new thermo stats....could be randomly sticking.

The 103 is an issue as well.

 

[Crosbyman]

can't say but the water flow under thermostat control may not be sufficient to provide the same cooling as a wide open flow with no thermostat.,

if you do not feel like pulling the cyl head try a new set of thermostats has suggested by saltchuckmatt to get even temperatures on both sides

flushed or not crud accumulates in 24 years .

 

[stresspoint]

maybe the mechanic stuffed up when setting the water tube in position OR broke / cracked it.

 

[Crosbyman]

This is a sudden problem after I had the motor serviced for a new impeller and a carb tune it happened the very next trip.


There is certainly relation or coincidence with the servicing of your engine and this " new " condition ...

If the shop is reputable they may take it back and have it investigated (free) as to why why this showed up after the work they did.

 

[Boatbuilds]

Update, I went out today after replacing the thermostats. They are both operating but still overheating on one side. I am unfortunately at a loss.

 

[Crosbyman]

time to dig in...if ph removal not your option try to fish some heavy mono line in the cavities try air pressure , try the cyl head removal to get a better look inside the jackets.. etc...

 

[saltchuckmatt]

What are the heat numbers....the same?

I'd pull the gearcase and try to reverse flush with air or water.
Most likely need to tear it down.

Do you live in mud dobbers country?