Evinrude 90 overheats quickly***UPDATED W/PICS!***

[3car]

Heres the story on the motor. I bought is off ebay, owner said it ran like a top. Right... I put kits in both carbs and new plugs, and it now runs very well. I ran it for about 10 minutes in the tank and everything seamed good, so I put it in the river.

Once its running at speed, it overheats in about a minute. I pulled it home and installed a water pump kit and a thermostat kit. I thought for sure that the thermostats were the problem because they were in rough shape. No dice. I put it back in the water and had the same problem. The motor can sit in a tank and idle without overheating, but it gets hot almost immediately under load.

The stream out of the tell tale is strong as well. Where should I look next?

 

[emdsapmgr]

Re: Evinrude 90 overheats quickly

Re: Evinrude 90 overheats quickly

I assume that the pressure-relief valves looked good when you were in the thermostat housing. They should open up when at planing speeds and flood the powerhead with cool water. If they function properly, but it still overheats on plane, you could have a restriction somewhere. Would be nice to know if it is both heads or only one. Take a laser temp gun with you and see which head overheats. I'd probably pull the head cover (not the head) and check the passages for debris. You can have a strong telltale but overheat due to failure of water to exit the powerhead through the thermostat housing. If that is not it, pull the heads and check the 4 rubber water diverters (by each cylinder.)

 

[3car]

Re: Evinrude 90 overheats quickly

Re: Evinrude 90 overheats quickly

Thanks emdsapmgr. I pulled the heads and shot a few pics of the deflectors. they look swolen compaired to others I've seen if I remember correctly< theres also a bit of corrosion in there.

Is this likely the root of my problems?

 

[HybridMX6]

Re: Evinrude 90 overheats quickly

Re: Evinrude 90 overheats quickly

I can't speak for the deflector tubes, I've never worked on a motor with them, but the water jacket looks horrible. I'd suggest cramming some rags in the cylinders and then trying to clean out as much of that buildup as possible. I'd probably replace the deflectors anyways while I was at it.

 

[ezeke]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

The deflectors are correctly positioned.

 

[emdsapmgr]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

As noted, they are in the correct position, but I'd be concerned about the upper one. Originally-the deflectors are supposed to be completely round. The middle one is pretty oval. It is intended to keep the water flowing vertically and to prevent it from getting to the horizontal area between the upper and lower cylinder. It appears that the middle one may be preventing/ restricting vertical (normal) water flow downward. The attached picture shows the normal appearance of a diverter in the block. It is almost touching the block where there is a tapped head bolt hole. Why not just get 4 new rubber hoses and replace all 4 to be safe. Looks like that powerhead water passages around the cylinders could use some cleaning-they look pretty salty.

 

[R.Johnson]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

I would take a look at those exhaust cover gaskets.

 

[3car]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

Problem solved. I replaced the deflectors and cleaned out the corrosion, and it runs cool all day long.

 

[kenmyfam]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

Problem solved. I replaced the deflectors and cleaned out the corrosion, and it runs cool all day long.

That's great news and a cheap repair. Enjoy.

 

[captainchuck1]

Re: Evinrude 90 overheats quickly***UPDATED W/PICS!***

Hi just wanted to thank u guys for this discussion ,one side of my 150v6 was running hot ,i went through everything no luck decided to remove the head and check and clean, guess what them deflectors were swollen closed got em out and will replace when i put the head back together, thanks so much