What to look for after an overheat?

[ad4par1]

Im sorry, I've made other posts about specific ?'s on my motor now I'm just looking for general information. Yes, it was the water pump and I have replaced it. Now I'm just working out the kinks as the motor ran fantastic prior to overheat now it runs like crap (low RPMS). I was just poking around for some general "where to look" starting points for overheated engines.<br /><br />1971 Johnny 50hp, electric shift (50ESL71)

 

[ad4par1]

What to look for after an overheat?

What are some of the key things to look for after an overheat to the point of tapping in the engine?<br /><br />Thanks!

 

[aeronutt29]

Re: What to look for after an overheat?

A new engine.... <br /><br />Without actually opening the engine up, it's very hard to tell what might have been damaged. The "tapping" that you mention could come from several places and none of them are cheap. Your best bet would be to figure out why it overheated in the first place and get that fixed. Has the water pump been replaced within the last few years? Is the thermostat stuck? Is there water squirting out the tattle-tale hole? Give us something to work with (a full story) and we'll get you pointed the right direction.

 

[aeronutt29]

Re: What to look for after an overheat?

Sounds to me like you've got a good winter rebuild project ahead of you. If the compression has dropped then you need new rings at a minimum. Not sure if you'll have any luck finding new pistons, but it's worth looking into. If the cylinders aren't scored when you open it up then you can probably get away with just new rings. It's unlikely that you will get your old performance back without opening the powerhead. I know that's not what you wanted to hear, but I just got done doing a re-ring job on my 100HP '69 Merc and it's absolutely amazing how much better it runs now. Besides, you need an excuse to go tinker with all those expensive tools, right?

 

[sloopy]

Re: What to look for after an overheat?

try running 16 to 1 oil gas ratio in it for an hour at full throttle, it should kick in to the higher RPM's sooner or later

 

[Steve135]

Re: What to look for after an overheat?

ad4par1,How hot did it get? I fried my 1984 Evinrude. Same thing water pump. I had to replace the head gasket. water jacket, all the exhaust gaslets just to get it to run.Then I did the intake side. All these could be a problem with your engine! My pistions were all fine they were getting fuel oil mix the the whole time that the overheat accured. The engine ran fine after the work was done, but I had no power still in the water. Turn out to be a simple plastic retainer ring under the timing base that mealted out of shape. This was found by a reader here at iboats. <br />Thanks to Joe Reeves!!!!! Just start like the manual says and do it systematicly and you'll find the problem.