1972 18HP Evinrude overheated

ArkansasGreg · Mar 28, 2012

Have a 1972 18 HP Evinrude that my dad left me that ran great until yesterday. Had been motoring along at about 3/4 throttle for 15 minutes when motor slowed and died. Would not restart. Smoke was coming from under engine cover. When I removed the cover the paint was smoking on the engine. I believe the water pump failed. Is there much of a chance that this motor isn't ruined? It was in great shape until this happened. Any advice on what to do would be appreciated.

jasper60103 · Mar 28, 2012

Re: 1972 18HP Evinrude overheated

Sometimes these motors can be forgiving. Start with a compression check. If you don't have a compression tester, you can borrow one for free at Autozone or Oreillys auto part stores. Post back with your results. Good luck.

ArkansasGreg · Mar 28, 2012

Re: 1972 18HP Evinrude overheated

jasper60103 said:
Sometimes these motors can be forgiving. Start with a compression check. If you don't have a compression tester, you can borrow one for free at Autozone or Oreillys auto part stores. Post back with your results. Good luck.

Thanks for the advice and I sure hope this particular motor is forgiving. What is acceptable compression pressure on these motors? 120 psig?

CatfishMN · Mar 28, 2012

Re: 1972 18HP Evinrude overheated

It can be lower. The most important thing is that they are close to even.

Salfal · Mar 28, 2012

Re: 1972 18HP Evinrude overheated

I would think that if did not lock her up it will still fire and run after a new pump,perhaps a little rich on the oil for a couple of gallons and just let her limber back up?

ArkansasGreg · Mar 29, 2012

Re: 1972 18HP Evinrude overheated

Ran compression check, 30 psig on top 55 on the bottom. Pulled the head and top piston is burned and there is some scoring of both cylinders. Looks like I'm going to have to have the cylinders honed and go with 0.030 oversize pistons.

jasper60103 · Mar 29, 2012

Re: 1972 18HP Evinrude overheated

ArkansasGreg said:
Ran compression check, 30 psig on top 55 on the bottom. Pulled the head and top piston is burned and there is some scoring of both cylinders. Looks like I'm going to have to have the cylinders honed and go with 0.030 oversize pistons.

Sorry to hear. Yea I agree, its probably worth fixing for sentimental reasons alone.

You have great resource of help here, and that particular model is a favorite on this site. I'm sure others with rebuild experience will chime in. Good luck.

edit: Here's one of my favorite youtube videos. This guy rebuilt an engine like yours...
http://www.youtube.com/watch?v=9WHqRvc5-zM&feature=my_favorites&list=FL3QpDWv9v2BbCl-1-MP9JSg

ArkansasGreg · Mar 29, 2012

Re: 1972 18HP Evinrude overheated

Having trouble locating some oversize pistons and rings. Any help would sure be appreciated.
Thanks all.

samo_ott · Mar 29, 2012

Re: 1972 18HP Evinrude overheated

I realize it will have sentimental value but finding a replacement power head will be a lot easier and cheaper if you're ok with going that route.

Beek14 · Mar 29, 2012

Re: 1972 18HP Evinrude overheated

I have a good 18 hp Evinrude powerhead off of a 1966 model if you're interested for that matter. Should work for yours.

ArkansasGreg · Mar 30, 2012

Re: 1972 18HP Evinrude overheated

I don't mind swapping out the powerhead if I can get a good one that I'm not going to have to rebuild. Is the powerhead in good shape with good compression and good internals?

ArkansasGreg · Mar 30, 2012

Re: 1972 18HP Evinrude overheated

Found a 1964 with 120 psi in both cylinders. How much of the 64 would interchange with the 72?

samo_ott · Mar 30, 2012

Re: 1972 18HP Evinrude overheated

The short block is the same I believe. You'd have to change a few odds and ends over to make it fit but it shouldn't be hard.

Beek14 · Mar 30, 2012

Re: 1972 18HP Evinrude overheated

Yeah, the one I have that's closest is a 66 18 hp Evinrude powerhead with about 95 lbs. per cylinder (cold tested). However a 64 would be about the same just 2 years older.

1972 18HP Evinrude overheated

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