poss overheat.

[dazid1]

Mercruiser 3.0 1984 on a pre alpha leg.
Took the boat out for its first test last week and at tick over all was fine but the higher the revs the higher the temp, back off on the revs the temp goes down, first I though its got to be the impeler but I have removed it and I expected it to be a mess but its not, going to change it anyway but I would of been happy if it was trashed. I am lost now could it be the head gasket, not shure how to test it on the boat, has anyone any ideas.
Thanks
Daz

 

[littlebookworm]

Re: poss overheat.

Start with the easy stuff first - check your thermostat. If it's more than 2 years old, change it. Then, before you pull anything else apart, check that the temperature guage is reading properly. Use a infra thermometer to check the temp in various locations on the block, manifolds, and risors. That will give you some idea as to whether the sending unit might be bad or if you've got some blockage in the cooling system. Also, check the exhaust flappers. I've seen them fail and partially block an exhaust pipe. Good luck. Hy

 

[dazid1]

Re: poss overheat.

Yes its over two years old, been sat in my garage that long, flappers ok as only just fitted the engine. Took the inpeller out its a bit odd looking, not worn at the tips like normally, not sure how to post a picture to show you. Hve read in another tread that pressure can be lost through the bellows, I hadn't thought of that, and as the boat seemed to be taking on water from the drive area could that be the problem? Will try and investigate but as ever its raining cats and dogs.

 

[Bondo]

Re: poss overheat.

not sure how to post a picture to show you.

Ayuh,.....

Down in the Tech, Non-boating forum there's a Sticky at the top, Explaining the process.....