AC removal causes oil leak?

Luis Felipe Patino lfpatino at pacbell.net
Mon May 6 20:30:27 EDT 2002


Solved!

thanks Martin, Jim and audifans for helping me
stop the oil leak that sprung out of the front of
my engine after removing the air conditioner
compressor, bracket and mounts :)

The cause was, indeed, not having replaced the
bolt immediately above the oil temperature sender
(and on which the front of the ac bracket slides
when tensioning the ac belt! what a stupid idea,
Audi!). B/c that bolt holds the oil pump tight to
the engine block, failing to put it back unsealed
the gasket between pump and block at that
location; therefore, the gasket allowed oil to
seep and even squirt past that unsealed point
depending on oil pressure/engine speed.

Putting that bolt and its washer back in and
tightening them to ~20 N*m stopped the leak dry :)

BTW at least in my JT engine those two ac "angle
piece" mount bolts don't go past the block wall
into the crank space or any oil passages, nor do
they hold anything else together other than the
"angle piece" to the block wall. As I initially
thought, they just screw into protruding threaded
dead-end holes really meant for the alternator
mount. No oil ever leaked out of those empty
holes: they only got wet from the oil squirting
through the gasket gap left by the missing,
split-personality bolt above the oil temp sensor.

Now that that oil pump bolt is back in, doing
_only_ what IMHFO it should, those holes are dry,
as is everything else that got wet. I'm glad I
didn't put the angle piece or its bolts back.

Moral: I bet most 5-cyl oil leaks from the oil
temp sender area come from a gap in the seal held
by that oil pump bolt (aka ac bracket bolt) above
it - even if no human hands have touched the ac
compressor or belt prior to the leak. If it can
break off chunks from the engine block (lister Jim
Bush's BTDT!) the behemoth mass of the ac
compressor and bracket can very well by itself, as
it gets accelerated and rattled during driving,
move the bracket bolt and hence unseal the gasket.
If oil leaks from the front of your engine, make
sure to check that bolt.

Luis

'87 4kcsq - with a dangerous weight off its now
dry engine :)



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