My Crazy/Interesting Theory Regarding LIM gasket failures
 

I must have read at least 5 stories in the last several months where someone swapped a motor from a junkyard and did not change the LIM gaskets and they ended up leaking shortly after the motor swap. My theory is that with the motor empty of coolant the LIM gaskets may "dry up" or become brittle and the rubber cracks, causing problems.

What I do know is that when a motor sits for a while without liquids the gaskets do dry up, I've seen this happen personally in a few situations.

Sure this is just a theory and not an extremely well educated one, but it seems like it could be possible. I guess the only thing we can reccomend is that if you go to swap a junkyard motor, you might as well change all the rubber gaskets on it while its out of the car since its easier. ;)

2 recent ones I found.there are more on here:

http://www.bonnevilleclub.com/forum/...ic.php?t=69835
http://www.bonnevilleclub.com/forum/...ic.php?t=73793 (could be a bad UIM)

Makes sense to me, I would support your theory.

Sounds like a plausible theory for SOME LIM gasket failures, but what about the ones that are driven daily and do not sit much?


Though you recomendation of changing gaskets while doing a motor swap makes sense to me, with the known problems they have why WOULDN'T anyone do that?

The amount of time they sit is moot. I've seen these fail in less than 2 years on L36's with DEX.

Many yards around here don't pull the engine until it's requested. That way it can be listened to and run if the buyer desires. While the theory seems sound, dryness doesn't make the gaskets go bad. They are sandwiched and the gasket keeps the moisture off them.

The failure is a design/material flaw.

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The material itself doesn't stand up well to the coolant, and then it's being held in place by a plastic carrier, itself only doweled in two locations across the length of the head. Mix the combination of gasket material, plastic carrier, coolant, and lots of heat, and it's a winning (read: losing) combination.

Metal carriers help keep the gaskets from deforming, and the newer gasket materials are designed to withstand the coolant/temperatures for longer periods of time. Put both of those upgrades together, and you're looking at a much longer life for your gaskets...