1991 Evinrude V4 overheating?

[pumfe]

Ok. Just some background on this boat. I bought it from a man that swore everthing was PERFECT with this boat so I dont know too much about the actual history of it. I have taken the boat out 3 times, the last 2 times I was towed in. I do know there was once a VRO that has been removed.

The issue seems to be that it is overheating. I can start it up and run it at idle on the garden hose, and it seems to be okay. Same with idling in no wake zones. However, when i open it up its good for about 500 yards and then it just loses power until its puttering and then dies. I take the engine cover off and it smells really hot and there is some smoke. The smoke disapates after the cover is removed, but still comes out of the tell-tale hole when cranking. It also will not start up again.

I replaced the plugs, wires, and empeller and installed a fuel seperator thinking that could have been my problem. Water seems to come out of the tell-tale fine. Took it out again today and the exact same thing happened. I have a book i bought, but it didnt seem to list any troubleshooting for this. I have no alarms on the motor and no temp gauge. Anyone have any ideas? I was thinking maybe a bad thermostat??? Not even sure if this motor has one.

 

[Mas]

Re: 1991 Evinrude V4 overheating?

What fuel to oil mix ratio are you using?

Yes, the motor does have a thermostat and I would look to replace that next. It could be stuck shut and not allowing cooling water all around the cylinder. I'm not sure where the t-stat is on your motor however. do you have a service maunal...if not, it's time to buy one. Buy the OEM, do not waste your time with the others!

MAS

 

[baiwan]

Re: 1991 Evinrude V4 overheating?

V-4 engines have two thermostats; they are in the cover where the two hoses lead water from both cyllinder heads. I don't think thermostats can cause that serious overheating there are bypass relieve valves.
I would remove the lower unit, the said hoses and run water in the tube leading from the water pump to the motor to find out if the gasket under the power head is ok. Mine was blown.

 

[emdsapmgr]

Re: 1991 Evinrude V4 overheating?

Baiwan is correct that when on plane, the pressure relief valves should normally open and permit cooling water to flow-even if the thermostats are not functioning. The fact that it overheats when on plane is a problem- I wouldn't run the engine till you get it resolved. Overheat lockups can cause significant block/ring damage. You need to get into the thermostat housing and have a look. I have seen the pressure relief valves melt and malfunction due to heat deformation. You need to check them and replace the stats when you are in there. Another possibility are the water diverters in the powerhead, behind each head. They could be missing or have moved out of position. I'd also make sure the four lower unit water intakes holes are fully submerged when running on plane. A factory manual is a must when getting into repairing.

 

[pumfe]

Re: 1991 Evinrude V4 overheating?

Hello Lads, Thanks for the feedback. I have removed the thermostats and they are both bad. One is stuck shut and the other is about half way open. The relief valves appear to be in good condition. The plastic is not melted or anything. I did not remove the shroud, so I cant see inside where the springs go to see if there is anything clogged up. There was some sand and stuff stuck in the thermostat housing. Im not too sure where to find the water diverters. I bought a book from iboats and its proved to be a waste of $30 thus far.

 

[Mas]

Re: 1991 Evinrude V4 overheating?

I bought a book from iboats and its proved to be a waste of $30 thus far.

The best manuals are the OEM shop manuals...sorry the one you bought wasn't much help. Anything other than the OEM usually are!

MAS