What do the motor heads think?

[cisco]

My buddy has a boat with a buick V-6

When the engine sees a load, the motor will seize and stall somewhere between 180-190 degrees water temp. It then cools down and runs again. It has a 160 deg thermostat.

I jacked around with the thermostat to make sure the cooling system is working. I runs cold with no thermostat, runs 130 with thermostat stuck open.

I'm thinking the engine was rebuilt with tight rings or something.

What do ya'll think? Any fixes? Run it with the thermostat open because cool is better than stick? Will the rings or whatever is tight eventually wear down or eat itself?

 

[jeepmauler]

IMO it's already started the proccess of eating itself. Everytime it siezes there is more and more galling occurring and that bish is doomed

 

[no excuses]

just as well pull the motor now before it siezes and does not restart, sucks to be broke down out in the middle of the water. probably cheaper to do it now before something goes boom.

 

[johneymav]

probably has forged pistons and the bore aint big anough so when it warms up there is too much friction and it siezes up

 

[whatthe?]

Pull that motor before you have a rowboat.

 

[JOOP]

Is the intake leaking??? But I agree with everyone. Pull the motor and replace it now before they're stuck out in the water.

I seriously doubt the rings have anything to do with it. If they did it wouldn't idle. Probably has a leaky intake, once it gets warmed up the leak gets bigger and sucks in more air, then stalls.

 

[ChopTop84]

With t-stat stuck open, Im surprised it gets as warm as 130. Have you checked the water flow? It sounds to me like maybe his water pickup is plugged partially, or the water pump impellor is toast. Im assuming its some form of I/O boat with a volvo or mercruiser outdrive?

Depending on the boat, the impellor could be in the outdrive housing, or it could be a raw water pump on the front of the engine. Either way, the rubber impellors are usually only good for a couple years before needing to be changed. If they disintegrate, they can plug up small water passages with bits of rubber paddle, and then you need to try and reverse flush the system with a garden hose or something.

I would also look for a vacuum leak. Its possible he's running lean, and thats why the high temps too. Then vapor locking the fuel lines or something.

I wouldnt trust the boat out on the water alone, but I wouldnt jump to yarding the motor out until I had some more info as to whats actually wrong first.

 

[cisco]

Thanks for the inputs. Seems like the impellor (2years old) is working good. He put clear hoses and the water is running fast.

I'm thinking this isn't a cooling problem since I cant measure anything on the engine over 200 degrees. Seems like a motor shouldn't stick at the temp it's at.