[Prev][Next][Index][Thread]

Update on Whooshing sound '95/530i/5-SPEED and Engine Mounts

Hi all,

Thanks to all of you for your replies to my whooshing A/C back in July. 
I finally got the car into the dealer for diagnosis of the whooshing 
sound. For all those interested here's what the Shop foreman told me:

A purge valve is causing the whooshing sound I am hearing. I can't
remember of he said the purge valve for the evaporator or the compressor.
The cycling of 10-15 seconds seemed appropriate for the conditions
that morning namely, extremely humid (> 80%), about 75 degrees F.
The A/C was maintaining 37 degrees output temp from the vents. The
cycling was necessary so as not to freeze up the evaporator. (This
is all accurate information as far as I understand the way A/C works).
The shop foreman did notice the abrupt deceleration while driving at 
slower speeds but did not admit that anything was wrong. They did 
check out the Freon level and the high and low compressor pressures and
everything checked out ok. I am of the opinion that this behavior
is somewhat common, more noticeable in a manual transmission since the
automatic can cover up such things, and probably nothing is wrong per se
BUT use of the A/C system should be more seemless than it is. Perhaps 
it is because it doesn't get too terribly hot in Germany so the testing that 
is done is not very extensive beyond pure cooling system capacity.

In any event, the shop foreman did notice a problem he says he didn't
like. When the A/C is on and the engine is idling, every now and then
the engine RPM's drop just low enough that the engine vibrations could
be felt as a rough idle. He claimed that was a defective engine mount.
This intermittent rough idle does not occur when the AC is off AND is
not attributable to the excess-sulfur-in-US-gasoline-disease because
the engine was just balance tested and all cylinders are within 
specifications.  Of course the car was under warranty, so both engine 
mounts were replaced.  When I received the car back, I did not notice 
an improvement in the intermittent rough idle when the A/C was on! 

Has anyone else had a dealer tell them the engine mounts needed replacement
at just 31,000 miles?. Is this intermittent rough idle purely an engine
RPM low enough that the vibration cannot be dampened by the engine
mounts? Any opinions are most welcome. I have not discussed this with
the dealer yet, as I would like to hear if others have had any similar
experiences first. Please feel free to post or e-mail privately.

Regards,

Kim Watters
E34/'95/530i/5-speed