58' Evinrude Big Twin overheating.

[thx997303]

It has water flow. Get that out of the way first.

The thing ran like a champ when I put it in the water.

After fishing for a while, I played around a bit with the boat.

I was adjusting the trim to see which one was right and I would run at WOT between adjustments. It appeared to be getting gradually slower. I thought it was just the adjustments. I forgot my GPS so I don't know for sure if it was or not. Just seemed to be.

I noticed the exhaust housing felt a bit warm and so I checked the head. HOT.

So I tried richening the mixture to see if it was a lean issue, no improvement. I only moved the mixture knobs within their movement and returned them to their original settings after I realized it wasn't helping.

Then, the motor started running without power. It would not run to full RPM and would sit there and rev up and down intermittently.

I tried choking the motor to see if it was a lean issue. The motor just instantly died.

There is oil under the powerhead that appears to be leaking at the gasket between the power head and the exhaust housing. Lot's of oil.

I noticed that the handle that is on the back of the outboard was almost falling off. The bolts had vibrated loose.

The plugs are both black and oily.

 

[thx997303]

Re: 58' Evinrude Big Twin overheating.

Bump.

 

[coolguy147]

Re: 58' Evinrude Big Twin overheating.

replace the t-stat?

compression?

spark?

 

[F_R]

Re: 58' Evinrude Big Twin overheating.

No thermostat on a '58 Big Twin.

The exhaust housing normally gets quite hot, up near the top. The head should be reasonably warm, but not hot enough to sizzle water.

Have you checked the water pump? If it is worn, expect it to run hot/overheat.

I think you have ignition problems. Leave the carburetor alone and check the ignition, especially the breaker points and COILS.

 

[thx997303]

Re: 58' Evinrude Big Twin overheating.

The head pretty well burned me near immediately. It was definitely overheated.

I will check the coils and breaker points. It did sound like it was firing on an entire one cylinder when it was having issues.

 

[thx997303]

Re: 58' Evinrude Big Twin overheating.

I haven't worked on the boat, but I have come to realize there was a significant fuel leak at the fuel fitting on the outboard.

If it was starving for fuel, but was still able to run, is it not possible that the lack of oil would cause the outboard to overheat?

Still trying to figure this one out.

I have new lower unit seals and a new impeller here, just haven't put em on.

 

[lindy46]

Re: 58' Evinrude Big Twin overheating.

Put the new impeller in and see what happens.