>
> one other related question can these coolers be rebuilt
> how do they fail the gowesty site says fails internally
> is there a rubber seal of some type the seperates the coolant from the
> tranny oil ?
>

I'm pretty sure it's constructed of 100% aluminum (aluminum alloy?), like
the engine oil cooler. When they go, it's apparently from internal
corrosion.  Like it says on the GoWesty site, if you have no record of it
being replaced, it's a lot cheaper to replace it than it is to deal with a
transmission and engine full of mixed coolant and ATF. I suppose the amount
of decay depends on how diligent the cooling system has been maintained.
Mine only had a little pitting at the hose attachment points, but the PO had
no service records and kept 2L soda bottles of water under the rear seat to
refill the cooling system when it overheated (which, with a choked radiator,
it did a lot). I chose to replace it.

--
John Bange
'90 Vanagon - "Geldsauger"