Overheated engine...need to change oil?

Messages
35
Location
Chico, TX
Before you answer, consider this: I had just changed the oil and had about 30 miles on the oil before the alternator/water pump belt snapped. Hot enough for the coolant to spit up out of the overflow bottle and lost about a cup of coolant. Engine shows no ill signs, oil is 5W-30 Pennzoil Platinum in a '91 Mazda MPV with a 3.0L V-6.
 

Narcoleptic

Thread starter
Messages
35
Location
Chico, TX
 Originally Posted By: GMorg
Did the oil darken alot or does it still look clear/amber on the dipstick?
Still looks the same as when I poured it in, no darkening.
 
Messages
1,714
Location
CA.
I agree with the others who said change it, it could be a waste, but then again it might not be. AD
 
Messages
3,756
Location
CA
 Originally Posted By: tenderloin
That is one reason why I/you run a quality synthetic...just in case stuff happpens. IMO the oil and engine are fine.
Agreed. It gives you that extra margin of safety in abnormal circumstances. I doubt the oil is hurt but again, oil is cheap and engines aren't. If the water temp just shot up quickly then you shut it down, it probably didn't have a chance to heat the oil out of it's acceptable range. If it was driven around for a long time, it's possible the oil got hot.
 

Narcoleptic

Thread starter
Messages
35
Location
Chico, TX
 Originally Posted By: GROUCHO MARX
How's the water pump?
Fine. It was changed with a new Mazda pump three years ago. The reason the belt snapped was poor maintenance. Once I pulled over and found the belt, I realized that I hadn't changed the belts since I changed the timing belt and water pump. Now all three belts are new, this is a vehicle we mainly drive during the summer. Lousy thing is I was thinking a couple days prior that I couldn't remember exactly when the belts had been changed, and I should get around to doing it.
 

Narcoleptic

Thread starter
Messages
35
Location
Chico, TX
 Originally Posted By: GROUCHO MARX
How's the head and gasket?
Good question. No milkshake on the dipstick, haven't done a compression test. Engine is an aluminum head/iron block. Part of the reason I'm thinking of draining the oil is to see if there is a milkshake. It hasn't been making any abnormal noises. One thing that was interesting that made me think the oil was fine is no HLA noise, which a Mazda engine will make itself heard when the oil is due to be changed. Its almost like a built-in oil change indicator. To calm my fears I went ahead and drained it. $20 is well worth the peace of mind. Looked a bit darker than new when it was draining out, but nothing else. One other reason I decided for the change was the weather, its getting into the high 90s next week and didn't want to chance it. If it was winter I probably would have left it in the pan. Thanks for all the responses.
 
Messages
14,778
Location
Illinois
If your oil would have gotten hot enough to discolar the oil your head gasket would have blown by now. No worries,
 
Messages
1,714
Location
CA.
You can pressure check the system, and that will tell you if you are leaking coolant internally or externally. Hopefully you have no leaks. For $20 changing the oil was a wise investment, no guessing or worries. I had a heater hose burst and the temp shot up pretty quick, I changed the oil the following day. AD
 
Messages
25,046
Location
ON, Canada eh?
You might consider a UOA after this fresh oil is changed next time. For $25 it will tell you if any engine damage has occurred and weather or not there is coolant in the oil from the head/gasket.
 
Messages
19,479
Location
Chicago Area
We don't know how hot is got locally in the engine. Maybe it's OK , maybe not. Over heated engines are one thing that should get their oil changed. Leave the filter in and swap in new oil. Big deal.
 
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