1980 Merc overheating

"So I changed the impeller and

"So I changed the impeller and pump in the lower unit, and I checked a hundred times and I am sure I did that right but she is still overheating, the antifreeze is full but she is still getting hot very quickly, does anyone have any ideas?"

"I'm having the same probl

"I'm having the same problem. Last week the engine was running cool, no problems. This week when I got the boat on step the temp went to 250 instantly. However, when I slow to trolling speed the engine cools down to about 160. The riser manifolds were really hot so I'm thinking the intake water pump went out and that at slow speeds the internal cooling system is enough to allow the engine to operate at lower temps. I'll have to pull the boat out and put on the engine flush attachment and see if I get returns from both outside water jacket ports. Now that I read your e-mail I can't think of what I will do if I change the waterpump and still have the same problem. Sorry I can't help but if you hear anything please post it. I keep my boat in Prince William Sound in Alaska and it's an all day trip to pull it out and get it home. Good luck to both of us!"

Frank and David
Check your th

Frank and David
Check your thermostat to make sure it is functioning correctly and also your heat exchanger.
You can get a build up of material in the heat exchanger that will restrict the flow of water through them and that will cause overheating problems.
Check those two things for starters and see how you go.
Cheers
Peter C

Boys:

Follow Peter's ad

Boys:

Follow Peter's advice and also take a look at the exhaust flapper. It may be jammed half shut.

Thanks guys..I will try those

Thanks guys..I will try those things...good luck to you too David

"David,

I spoke to a mechan

"David,

I spoke to a mechanic today and the tips he gave me where pretty much the same as Peter said..the thermostat, and coolant water pump may be bad..also the hoses,risers,manifolds and what not could be clogged with dirt or silt or anything..so that is really all i heard..I changed the thermostat and impeller and am having a buddy of mine come and look at it sometime this week to check for anything else before i put it back in the water..i would also suggest checking your compression in the engine...so you can tell if you are dealing with a bad engine or just a cooling problem"