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?

 

[Texasmark]

Possibly the mechanic that setup the carb jets didn't get it right. Running an engine too lean has caused higher than normal temps and as I recall the carbs on those v4s (I had a new 1972 125 HP Johnson) had separate channels for each cylinder....aka 4 paths into the engine.....I assume that each has its own low speed set screw. I've never tuned a V4 so I am just speculating. I had the 125 for 7 years and never touched anything including the impeller...it just ran and ran.......no overheat problems.

 

[racerone]

I would think there is a severe corrosion issue in the exhaust housing.----Where water flow splits to go to either side.----May have a look at some housings later today to see if that is possible.-----And a co-incidence it was noticed after shop worked on it.

 

[Boatbuilds]

I would think there is a severe corrosion issue in the exhaust housing.----Where water flow splits to go to either side.----May have a look at some housings later today to see if that is possible.-----And a co-incidence it was noticed after shop worked on it.

I ended up taking it to the shop. The mechanic there is top-notch and has been working on these motors longer than I've been alive. I trust him with any work he does.

In this motor, there’s a part called the upper inner exhaust housing. Inside the housing are channels that can become clogged over time. The problem is that you can't easily clean them out without taking the housing completely apart, which requires removing the lower unit and the head—no small task.

Luckily, there’s a way to "cheat" this. By adjusting the thermostats to allow more water flow, the mechanic can bypass the clogging issue. He’s never had any complaints with this modification, and the overheating problem is resolved.

 

[cyclops222]

GAG Geezers are good

 

[Crosbyman]

if passages are clogged with minerals any chance a good bucket run with "Salt Away" would help ?

Concentrate Kit - SA32M | SaltAway

www.saltaway.com

see utubes on desalting overheating engines

 

[saltchuckmatt]

So....out of curiosity what are the head numbers now?

I've seen reps crush springs on thermos to adjust temps but your numbers were getting up there. Might be a "way around" but certainly not a fix.

Id do like Crosby says....pickle that thing. When it's up to temp and under idle, flow that stuff in there until it's foaming on the ground, shut it off and let it sit a week then try to blow some of that stuff out of there.