Mercruiser 470 repower 1978

[surchin]

Originally Posted by THEFERMANATOR

Mercruiser didn't put a heat exchanger on that engine for no reason. The mixture of aluminum and dissimiliar metals is BEGGING for corrosion. If you're doing it for a short time and plan on throwing the engine aesy afterwards, go ahead. Otherwise install the 4" heat exchanger and fix your combustion leak.

Yes I understand. I did put in a 4" heat exchanger few years ago. This is pretty much a last chance for this motor as the pressure in the coolant system is going somewhere and the head gasket leaking seems to be the likely place.

I can't get the riser elbow off now from corrosion and rust. But Im likely loosing coolant from cracks in there too.

I've had the boat almost 10 years and I've done a good job keeping it going. Out boating season is 12 months and Ive managed to get out year round for 10 years with this old motor.

I definately got a motor that had not been very well maintained before me but I liked the hull setup at the time and boat was cheap. I can only say I wish I would have re powered in the beginning instead of eBay parts and labor to keep it going. But I did not have the big money for that. Just had to keep chasing problems but usually got them solved.


Right now I have a lot $ in a new outdrive and trim pump ($!!!) and I'm just trying this new open raw water system as pretty much last resort. The closed cooling system is not working for my motor. We have a good wash down here at our ramp I always flush it straight out of the water so I'll keep doing that against salt water corrosion.

I really have a good feeling it will work. Motor runs great. Starts idles shifts all good. Carbs clean. New electronic ignition My Trailer is good. It's just this dam overheat keeps happening. This is a few hundred dollar fix at this point.

Thanks you all for the input I really appreciate it. Being able to run it by guys that know the situation. I'll post up how it turns out.
Scott