Overheating

[michaelogden]

Hey guys,,,,I have a 1990 Johnson 225 Looper,,,,have done a lot of work to her,,my question is this,,,my lf bank runs significantaly hotter that the rt,,,,I put a brand new t-stat on the lf side & no change,,,the overheat horn works & both sides when I ground out the horn it screams so I know the horn is working,,,,but when running the horn never goes off,,,,this is while I have the muffs on the lwr unit,,,I hav'nt been in the water yet so am I paranoid or is this normal.

[rochelle howell]

What are your temps left vs. right? Over 180 ? Maybe one stat stuck all or partially open, one stat stuck all or partially closed.
Test water jackets while running with infra red temp gun. Top of head vs. bottom of head. Might expose possible water jacket blockage.
Water pump been done? Full kit with seals and grommets, etc.
Weak pump along with low rpm possible cause?
Water diverters if it has them?
If you ground the horn and it goes off thats good. I don't think that tells you if you temp sensors are working or not, or your wiring to horn has continuity.
Had similar problem with evinrude 1977 140 HP. Partially clogged water pump housing, hard as a rock impeller, one t-stat stuck open, other stuck shut. One poppet valve stuck open. Hard as a rock poppet valve grommets .

Complete water pump rebuild, two t-stats, gaskets, poppets, grommets and springs got me all sorted out. Still have my new head and water jacket gaskets sitting on a shelf, didn't need ' em. Will do in near future.
Hope this helps!

[michaelogden]

Brand new water pump,,,,,@ first the rt bank was getting hot so I took the rt t-sat & put in on the lf side & the lf t-sat on the rt,,,,,,,,,everything switched @ that point so the rt side was cool but the lf was now getting hot which told me bad t-stat so I ordered a new one,,put it on the lf side & no change,,,,the tattle tale is peeing plenty but the lf bank is still getting to hot so i'm really scratching my head now,,,what's your thought???

[rochelle howell]

Possible bad new t- stat? Improper install? Gremlins? Ghosts?
Swapping side to side good indicator of problem.
When doing thermostats on engine with 2, might be better to replace both at same time. Not that expensive, and good preventative maintenance.
Swap'em back and see if overheat moves to other bank.
Good luck!

[michaelogden]

Thanx Bud,,,that was what I was going 2 do next,,,swap it back & see what happens,,,,,,i'll get back to ya,,Thanx again

[flabum1017]

Running on a hose may not be enough water... try it in the water............

[michaelogden]

Hey guys,,I'm running 30-40 degree difference bank to bank,,,the rt bank is the hotter one,,,my pryrometer showed rt bank cly around 180 & the head was 210ish,,,,,,,lf bank cyl 145 head 185ish,,,,lf side has the new t-stat,,,this is while hooked up on the muffs,,,,what temp sets off the alarms & they are working but have not gone off while I've running with the muffs.

[flabum1017]

Have you tried it in the water? sometimes a hose won't supply enough water............

[michaelogden]

No not yet,,,,I didn't want to drop her in the water without a second opinion first.

[copano]

I never trust engine temps on a hose, sometimes we have low water pressure at the shop and get over heats running on muffs.
The ONLY way to know for sure is run it in the water and test with an infrared temp gun.

I see you're in Corpus, I'm just north of you and we see a lot of engines requiring a cooling passage descale after the 15 year age mark.
Again we only diagnose cooling problems is in the water, to do otherwise is bad form.

[michaelogden]

You were the 2nd opinion I was looking for,,,,,,I was the first so to the water we go

[copano]

One other tip, just back it down the ramp and run it on the trailer, also under load, if it heats up you know you have a problem, beats being stuck out on the water.
But the real test is run at wide open throttle for 10-15 minutes, if it gets hot and you've already done the water pump and thermo's it's likely the heads are scaled up.
It's more pronounced in the summer when bay temps are close to 90 degrees, but it all depends IF its scaled and how bad.

[racer]

1990 has a water control valve that directs water to back of thermostats to keep them seated and has a cross over from Stb to port side. If valve or cross over are not working correctly could lead to your issue.

[michaelogden]

Thanx,,I'll defintetly ck that out tomorrow after Turkey,,have a GREAT ONE YOURSELF

[michaelogden]

Hey Guys,,,just checking back in,,,I dropped her in the water for a test run,,,never once overheated,,,no alarms ever went off & they work but there is still a significant heat difference from bank to bank,,,,,rt side running around 175-180,,,lf side 150ish,,,,,,,RUNS LIKE A RAPED APE,,,,,,,,do I need to worry or keep on fishing,,,I appreciate everyones help getting me this far.

[racer]

The 150 side is more where it should be. Thermostats open at 143. IMO 180 is too warm.

[michaelogden]

Thanx Bud,,,i'll keep looking for a restriction

[Motv18]

Stuck poppet? If only the t stat opens not enough will flow, normally the popets are the cooling main control t stat is for low water pressure operations.

If it has poppets