what happens when an engine has too much oil?

[Stu Pidd]

Going to an insurance auction tomorrow. There is a low-mileage Tahoe with a 5.3 I'd like to put in the '68.

The only problem- Looked at it today, and when I pulled the dipstick, the oil level was way over the "full" line- Probably a quart+ over.

Any cause for concern?

The plan is to yank it out of the donor, and bolt it into the Chevy without opening it up.

[70']

Depends.....my guess is, if it's going to auction someone checked the oil, seen it was a little low and just dumped a quart in knowing well someone would pull the dipstick on it before bidding on it. If it hasn't been run long term that way it's of no concern. Typically, too much oil will cause general oil leaks and there is such a thing as too much oil pressure. That can burn up valves, blow gaskets and wreck some havoc, especially when done long term. If the oil looks clean at the present I wouldn't be concerned, but if you end up winning the auction, I would perform a complete oil change on the vehicle right where it sits and get it corrected before you even start it up.

[jayoldschool]

Quart over? No big deal. 5 over... problems.

[01chevduramax]

If possible try to get under it and loosen the oil drain plug. Just a tiny bit. It could have coolant in the oil. Water settles to the bottom right away. If water/ antifreeze trickles out you know it has a blown head gasket or worse. The extra coolant in the oil pan causes the oil level to rise.

[Boog]

Be careful with this one. I had a cracked head on my 06 5.3 last year. It kept losing coolant when finally the oil level went up a couple quarts. The oil was not milky but under the valve covers and oil filler cap was the thick jell like substance you get when coolant mixes with engine oil.
My problem as I said was a cracked aluminum head. The crack was not in the combustion chamber so no engine miss. The crack was around one of the head bolt holes.
It is a distinct possibility the one you are looking at has one too.

[MARKDTN]

Originally Posted by 01chevduramax

If possible try to get under it and loosen the oil drain plug. Just a tiny bit. It could have coolant in the oil. Water settles to the bottom right away. If water/ antifreeze trickles out you know it has a blown head gasket or worse. The extra coolant in the oil pan causes the oil level to rise.

X2. Be careful.

[snipescastle2]

biggest problem would be that your plugs will foul out, but too much oil will cause foaming in your crankcase and possibly over pressurizing your oil seals causing leaks.HTH,
Ben

[67ChevyRedneck]

Did someone just recently start it? Did you clean the dipstick off and recheck it?

[Stu Pidd]

Okay, guys, the auction report-

This comment got me thinking:

Originally Posted by 01chevduramax

If possible try to get under it and loosen the oil drain plug. Just a tiny bit. It could have coolant in the oil. Water settles to the bottom right away.

Since it would not be allowed to loosen the drain plug at the auction site, I simply looked at the coolant level- It was low!

This Tahoe had seemingly minor damage, limited mostly to the front suspension. So why was it totaled? Possibly a crack in the engine, resulting in a coolant leak?

I decided not to bid.

I've purchased a few vehicles from the insurance auction before, and have never had a bad engine- I assume that the car had to be running well enough if it got in an accident.

Chances of a bad engine are far higher in a barn find that has been sitting for years than at an insurance auction.

Maybe I missed out on a great-running engine, but why take the chance? I'll see what the next auction brings.

Thanks for all the wise comments.

[motorcritter]

My rule-of-thumb with engine problems is 'when in doubt, DON'T'! I used to run a transmission shop, and the owner used to go to the auction and pick up cars with engine problems, for repair and resale at his used car lot. I told him that he needed to ignore those cars, and get the ones with transmission problems! I've been looking for an LSx donor for the '71 Cheyenne, and running wrecks are usually a good choice for driveline stuff, but I've seen a few cracked aluminium head engines- and the scenario you described is a good tip-off.

[jeffahart]

Why it's looking overfilled in more concerning to me. Result of overfill is foaming, the foam is air bubbles, no lubricant inside bubbles = friction. But like said above, how did if get overfilled? I would be suspicious for sure. Cook it into the price.

[outdoorsman310]

put a 8100 engine in it!