Change oil after Overheating?

[Condor1970]

Many of you on here know I smoked my impeller, when the muffs fell off during testing the engine/outdrive. The temp was in the red I think for a few minutes.

I also note it has a fresh oil change just before this happened. It's a Merc 3.0L. How much oil does it normally take to take it to the full line?

When I changed the oil, to get it close to full, I needed almost 4-1/2qts.

One thing I note is the oil smells a little like gas. Not sure if this is because it mixed with some of the older oil that had the same thing, or if the pump is leaking.

Anyway, since it got overheated, is it a good idea to give it a fresh oil change again before running it again?

 

[thebigt32]

Typically a 3.0 takes 4 qts if you don't replace the filter and they say to add a qt if you change the filter so 4 1/2 should be good. Sorry to hear about the red line. I would definitely say change the oil again as the heat most likely broke it down fairly well. Kind of blows to have to change it again but to be on the safe side I would. Have you emptied any of it out? I would assume it would be pretty thin and not work as well. If you overheated that long your exhaust bellows must be toasted. I hope your going to replace them. Also, have you tried to turn the engine over since overheating? you didn't fry the rings or seize the engine did you?

 

[Condor1970]

Yes, when the engine was cooling down, every few minutes I cranked it over to make sure it wouldn't sieze. The engine still runs fine. In fact, the exhaust hoses are all fine. Even the one right off the top exhaust elbow, which gets the hottest. The exhaust shutter which is coated in rubber is also fine. I will replace the shutters anyway, since they were old.

Keep in mind, even though it got overheated in the red, it was idling the whole time while I was testing the shifting of the outdrive. No high rpm's at all.

If I do an oil change, I will definitely replace the filter. It's just a habit of mine. Filters are only $6.

Heck, since I got the lower off for a new pump, I may just pull the upper too, and install a new shift cable, since I've had some issues with that.

 

[tpenfield]

The overheating itself is not really enough to cook the oil, but if you smell gasoline in it, then best to change it out.

 

[Volphin]

Gas in the crankcase is not a matter to take lightly on ANY vehicle. Examine that fuel pump and carb closely.

 

[Condor1970]

I do have a feeling if there is gas in the oil, then it was the horribly bad condition the carb was in until I rebuilt it. I just got it reinstalled, when all this happened, so I know for a fact the carb is good. I also think the old fuel pump may part of the problem, even though the fuel pump itself is running fine with plenty of pressure. I suppose its possible a new pump may be in order as well. I think I will change the oil, and run it again in a week when I get new parts for the outdrive, then see what happens.