Is it dangerous to drive my Trooper with an antifreeze leak I can't find?

Dear Car Talk

Dear Car Talk | Nov 01, 1997

Dear Tom and Ray:

I own a 1988 Isuzu Trooper II that has 74,000 miles on it. A few months ago, we
noticed that it was leaking antifreeze. No one can pinpoint where the leak is
coming from. There is always coolant in the reserve tank. The hoses are fine
and the head passed a stress test. We can smell the antifreeze near the front
of the car after we've driven it and parked it. And a mechanic did find some
antifreeze in the number three cylinder. Is it dangerous to drive? And will it
be expensive to fix? -- Beverly

TOM: No, and yes.

RAY: Here's the story, Beverly. I think you have several leaks. The "internal"
leak in your number three cylinder is by far the more serious of the two.

TOM: That's not the leak that you're smelling. But it's the one that's going to
cost you many hundreds of dollars to fix. So you want to address that one

RAY: The coolant probably got into the cylinder through a blown head gasket or
a crack in the cylinder head. I don't know what kind of stress test your engine
passed (was your mechanic running on a treadmill while he worked on it?), but
it couldn't have passed a bonafide head gasket test and still ended up with
coolant in a cylinder.

TOM: It's not dangerous to drive. The worst that will happen is that you'll
eventually run out of coolant and the engine will melt. But you can prevent
that from happening for a long time by simply keeping a close eye on the
antifreeze level. Just make sure you check the level in the radiator itself
(when the engine is cold!), since a leak could prevent the reserve tank from
giving you an accurate reading.

RAY: Eventually, however, if you want to keep this truck, you're going to have
to fix the internal leak, and that's big bucks.

TOM: Your other leak, the "external" leak that you smell, could be coming from
anywhere. But based on my experience, I'd look carefully at the "weep hole" of
the water pump.

RAY: It may be an insignificant leak, because a very small amount of antifreeze
can create a lot of antifreeze smell.

TOM: And it'll look even more insignificant next to the new cylinder head you
need. So explore that internal leak first, Beverly, and make sure you plan to
keep the car before fixing the small stuff. Good luck.

* * *

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