Is it purely coincidence that I've gone through three different gaskets in a year?

Dear Car Talk

Dear Car Talk | May 01, 1998

Dear Tom and Ray:

I own a '93 Dodge Caravan with 65,000 miles. When the van had 50,000 miles, I
started noticing oil spots on the driveway and garage floor. Four hundred
dollars and a new head gasket later, the oil leak was supposed to be corrected.
It wasn't.
After several more trips to the dealer, they decided that the valve cover gasket
needed replacing, and they did it free of charge. Funny as it seems, I still
have an oil leak. After taking a 1,000-mile trip and adding a quart and a half,
the dealership says the rear crank seal is bad and needs to be replaced. That
would be another $300.
What do you think? Should I unload this thing as soon as possible? Or is it just
coincidence that I've had three gaskets go bad within a year? I'm told not many
people bother to replace the rear crank seal, but I hate having oil spots on the
driveway. -- Tom

RAY: Three bad seals, huh? The Monterey Bay Aquarium had three bad seals one
year. Apparently, they put a few posters for the shark exhibit near the seal
tank, and they never heard another peep from them.

TOM: I think it is a coincidence, Tom. Head gaskets shouldn't blow at 50,000
miles, but they sometimes do. It could have been due to poor manufacturing, or
it could have been caused by engine overheating.

RAY: And the valve cover gasket was probably leaking because they put it back on
wrong when they did the head gasket job. That's why they replaced it for free
when they later discovered it was leaking.

TOM: The rear crank seal (more commonly called the "rear main seal") leak is
probably unrelated to the other two. However, it's worth checking the Positive
Crankcase Ventilation (PCV) system before you go any further. The PCV system is
supposed to let pressure and fumes out of the crankcase. If too much pressure
builds up in there, it could cause seals to blow.

RAY: If your PCV system is operating correctly, then the leak is more of an
aesthetic and environmental matter at this point. A quart and a half of oil
every 1,000 miles is not much, mechanically speaking. Certainly not enough to
endanger the engine, provided you keep an eye on the oil level and never run let
it run too low.

TOM: And for the $300 it costs to replace the rear main seal (that's $3 for the
seal, and $297 for labor, by the way), you could buy 300 quarts of oil. That's
enough, theoretically, to cover you for another 200,000 miles, which you'll only
get out of this car in your dreams!

RAY: So it's up to you, Tom. Fix it if it bothers you or if you're particularly
concerned about the environment, or just keep an eye on your oil level and park
over some pizza boxes from now on.

* * *

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