Does antifreeze poured in the crankcase mean it's new engine time?

Dear Car Talk

Dear Car Talk | Apr 01, 2009

Dear Tom and Ray:

I have a soldier who mistakenly poured a gallon of antifreeze in his crankcase. He then started and ran the car for several minutes before he realized what he had done. He is being told that he needs a new engine by one mechanic, and that he doesn't by another. I think he is probably "up the creek" and will have to get a new engine. What is your guidance? By the way, I'm not too proud to say I had to replace someone's brake system because of a similar mistake I made years ago. Antifreeze, no light and unfamiliarity with a vehicle can be a BAD combination.

-- Peter

RAY: Well, Sarge, I can tell by your relaxed, understanding attitude that it wasn't YOUR car he poured the antifreeze into!

TOM: The car might be fine. While antifreeze isn't as good a lubricant as oil, it does have lubricating properties. After all, one of its jobs is to lubricate the water pump as it passes through.

RAY: So it's nowhere near as bad as putting, say, water in the crankcase. Or Cream of Wheat.

TOM: And if he really ran the engine only for several minutes -- and a lot depends on his definition of the word "several" -- he might not have cooked the bearings, which is the worst-case scenario.

RAY: There are a couple of clues he can look for. One is that he's burning oil. If he notices a cloud of blue smoke following him around everywhere he goes, that's a sign that the rings were damaged, and suggests that the bearings may have been harmed, too.

TOM: But the definitive test is an oil-pressure test. Have him borrow an oil-pressure gauge from the motor pool. You unscrew the oil-pressure switch, and screw in the gauge in its place.

RAY: Then find out what the spec is supposed to be for this car. It'll be listed as a certain pressure, in psi, at a given rpm. So, maybe it's supposed to be between 45 and 60 psi at 2,500, for example. We don't know what the spec is for his car. But we're pretty sure it's not zero!

TOM: If the oil pressure is up to spec, he's fine, and he can forget all about this little incident. If it's on the low end of the spec, he can try using a thicker oil while he attempts to unload the car on someone of lower rank.

RAY: But if it's below spec, he's cooked. In that case, since it's probably burning oil and blowing blue smoke to beat the band, he may be able to sell the car to the Army for use in camouflage duty putting out a smokescreen to protect you guys from being spotted by the enemy.

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