'95 Johnson 90HP overheating only on starboard side?

[Shadowjaguar1]

A quick rundown. After having a new used motor installed , this has happened twice now. Before the first time, I tested the installation on shore with rabbit ears and I had no problem. I did not test for long as the water pump was working and the motor sounded great. But once I shot across the water for about 10 minutes at high RPM's the motor started clattering and there was smoke. By the time I slowed the boat and turned the key off the motor quit. I found out later the smoke was from the wire insulation. After replacing the wiring (including checking the wiring) and the power pack I completed a more extensive test before heading out. I let it run for about 25 minutes on land while adding throttle now and then. Being on land I did not add too much throttle. When I had it in the water I eased the motor RPM's gradually higher for about 2 minutes and then back down. I did this about 5 times. No issues and water was still flowing through the motor. Feeling confident I increased the RPM's to about 3000 and the speed to around 20 for about 30-40 minutes. Steady. You guessed it. The engine starting clattering again and more wire insulation melted. I understand this sounds like a cooling issue, but the water pump appears to be operating fine. Water is exiting from the exhaust and the upper tube just fine. The wire issue seems to be only on one side. Can only one side be blocked and all other functions appear normal. Thank you for any assistance you can give.

 

[tboydva]

Re: '95 Johnson 90HP overheating only on starboard side?

I never melted wiring, but I repowered my boat with '95 Evinrude and had issues overheating. This may be way off, but I had my motor mounted too high and after getting my wife to look over the stern underway (she goes about 100 lbs soaking wet, so the stern didn't sink down and bias the visual), and the cavitation plate was a bit high out of the water (so it was sucking some air into the water intakes). Lowering 1.5" did the trick for me. Just a thought.

 

[metriccrescentwrench]

Re: '95 Johnson 90HP overheating only on starboard side?

First you need to verify the overheat alarm is working, you should have heard the alarm buzzer if overheating is the problem. (There's a temperature switch on each side). And yes, it's possible to have cooling issues with just one bank.

Do you have a factory service manual? If not you should get one (the actual OMC manual and NOT one of the one-size-fits-all-generic ones).

 

[daselbee]

Re: '95 Johnson 90HP overheating only on starboard side?

If wires were melting on your motor because of the engine overheating, that engine got WAY WAY WAY too hot.
It would be nice to know what wires melted.

I suspect a reg/rect problem , high current flow at higher RPM, but there is not enough information yet to tell what is going on.

Which wires melted?

 

[boobie]

Re: '95 Johnson 90HP overheating only on starboard side?

Have you checked the the temp on top of the block on both sides just before the cyl heads? Not saying this is your prob but you might have some water defelectors in your block swelled up.

 

[Joe Reeves]

Re: '95 Johnson 90HP overheating only on starboard side?

Test the warning horn system..... Engine not running but with the key turned to the ON position. Ground out the overheat sensor wires that protrude from each cylinder head (Tan Wire), one at a time. The horn should sound with each grounding.

If the horn sounds as it should, then obviously that sensor requires replacing.

To overheat on just one bank, the problem would need to be either a faulty thermostat or swollen water deflectors, or both.

(Water Deflectors)
(J. Reeves)

Water deflectors are actually lengths of 3/8" outside diameter rubber hose, installed between the top cylinder and any cylinder beneath it, and also between the bottom cylinder and the block. The purpose of the deflectors is to have the water follow a definite path around the cylinder walls. Unfortunately the deflectors between the cylinders will at times swell sideways due to either a previous bad overheating problem, or simply due to age and salt corrosion. This causes a water flow restriction which usually allows the water to cool sufficently at low rpms but not at the higher rpms.

This hose material can be purchased reasonably at any automotive parts type store if you care to make your own, or you can purchase individual deflectors at any Evinrude/Johnson dealership at a somewhat higher cost.

Removing and installing them can be a hassle at times, but not always. I use a sharply pointed scribe with about 1/4" of the tip bent at a right angle whereas I can reach in, jab the tip sideways into the rubber, then yank it out. It's necessary to clean the seating surfaces where the ruber contacts the block with a small rat tail file to eliminate salt deposits etc. When installing the new rubber deflector, coat the deflector and the metal surfaces with WD40 which will act as lubrication to allow it to go in as easily as possible.

Make sure that you insert something into that deflector area before cutting and installing the deflectors if you make your own so that you will be certain that they are the right length and also that they will be seated properly. Usually a very small amount will be left extending about the block sealing area..... simply cut the excess off with a single edge razor blade.

 

[emdsapmgr]

Re: '95 Johnson 90HP overheating only on starboard side?

OMC made two completely different 90 hp engines in 95. One is a crossflow, the other is a looper. No similarity whatsoever. It would be helpful to know which engine you have. Please post the model number of your engine.

 

[CH1968]

Re: '95 Johnson 90HP overheating only on starboard side?

Have you checked the the temp on top of the block on both sides just before the cyl heads? Not saying this is your prob but you might have some water defelectors in your block swelled up.

where exactly are you referring to when you say on top of the block on both sides just before the cyl heads?


Cameron

 

[Shadowjaguar1]

Re: '95 Johnson 90HP overheating only on starboard side?

Thank you for your responses. The model number is J90TLEOR. It has melted two different sets of wires. After the first time it happened the motor sounded great, when the wiring was replaced. The alarm is missing from this motor. You can bet I will be installing something immediately.

 

[emdsapmgr]

Re: '95 Johnson 90HP overheating only on starboard side?

You have a 95 crossflow 90 hp engine. You might want to rent or borrow a laser temp gun and determine if either head of the block is actually overheating, or if you have an electrical short. Most auto parts stores will rent this type of gun and it works well. You can have a strong telltale and the engine can still overheat. That engine has two thermostats, one for each head. Their job is to regulate the water flow out of the block. If either stat sticks shut, water won't circulate through block and it will overheat at idle. If you find the engine is actually overheating, I'd get the thermostat housing opened up for inspection and probably replace both stats. That engine shipped from the factory with two, simple overheat switches. One in each head. They connect to the horn in the control box. When a head gets hot, the switch turns on the horn at 212 degrees. (that's hot) Normally, your engine should idle in the 143-155 range.

 

[markk900]

Re: '95 Johnson 90HP overheating only on starboard side?

No expert here but for things to get hot enough to not only melt but smoke wires I do not think there is a cooling problem - sounds much more like an electrical short. 212 degrees is not enough to melt wire insulation and as emdsapmgr points out that would be where the alarm would kick in.

Mark

 

[Shadowjaguar1]

Re: '95 Johnson 90HP overheating only on starboard side?

I suspect its a cooling issue because two different sets of wires melted. But on the same side. The second time melted the plastic wire protection around the wiring on top of the engine block. I do have another issue though. What type of socket do I need to get the head cover off. The recessed indentations appear to be offset enough to not allow a typical star socket to fit. Thanks again.

 

[boobie]

Re: '95 Johnson 90HP overheating only on starboard side?

Head cover? Star socket? Please explain better.

 

[Shadowjaguar1]

Re: '95 Johnson 90HP overheating only on starboard side?

My apologies. I am referring to the cylinder head water cover. The bolt heads are counter sunk and the cover holes seem to be offset enough to make a star socket (which has thinner walls) unable to make good contact for removal.