[mefforddk]

I have had this weird "humming" noise coming from the front of my engine bay in I slow rev up the engine. I happened to put my hand on the passenger side fender and felt the vibration, so I naturally thought the engine mounts. However, I had just replaced both. I kept searching and I found that it is coming from the oil cooler. I slow increase the throttle and the oil cooler itself will "hum". Any one got any idea what is going on?

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[Johannvb]

I have no idea, but in a house water pipes tend to vibrate when there is air in them. I wonder if that is the case with your oil lines. The other option is that maybe there s a blockage in the pipe or cooler. I will be following this topic with interrest.

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[Ryan]

Seems like the S2's had a problem like this and it was a valve on the oil pump that was the problem. I am a little foggy on this so a search might be in order. First I have heard of this on 968s.

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[Ryan]

I found this about the oil pressure relief valve on a S2 site.....Hope it helps. Hey both are 3liter engines, it could be the same.

For all who are not in touch with it. I had a 'moaning'
noise front right in my 1991 944S2. It was rpm independent
and happened on a hot engine only. After a lot of testing
and searching it appears to be the oil relieve valve.

Diagnose:

- warmed up engine to normal temperature
- engine running at idle speed
- turn on front lights to (min.) low beam
- touch oil lines from engine to
oil cooler at the engine side.
( put your left arm very carefully
into space between passengers side
headlight and windshield washer
reservoirs. Do not touch power
steering trombone cooler lines.
Oil cooler lines ar the big
rubber one's underneath. Be careful
not to smash your fingers into
power steering pump belt!!!)
- slowly raise engine speed by opening
throttle (with your right arm) until
moaning noise becomes audible
- oil lines are now pumping and vibrating


Fixing:

- buy two rubber rings, part# 999-707-145-40 and 999-707-144-40
(one is a green one, other a black one, about $1-2!)
- remove plastic air deflector pan mounted under engine
- locate 24mm 6-edge-screw near exaust, mounted into engine
housing below oil-to-water-cooler-oil-filter-unit, right side.
- remove 24mm 6-edge-screw
- a metal pipe thing comes out
- at front end you will see first old rubber ring
- 6-edge-screw and metal pipe are not fixed together,
both things are weakly fixed by the second rubber ring
which is not visible
- pull heavily 6-edge-screw and metal pipe in two directions
to come apart into two pieces.
- NOTE: A spring and a bolt comes out of it. Do not lose
it! Remember, which one is assembled first, second etc.
(Spring, bold, oil piston)
- now you see the second old rubber ring, it will be demolished.
- replace this second old rubber ring by the new -BLACK- one.
- assemble Bold and Spring in right direction.
- push 6-edge-screw and metal pipe carefully together to be
one piece again, weakly fixed by new -BLACK- rubber ring.
- replace first old rubber ring by new -green- one on top of tube.
- clean the whole thing carefully
- replace old aluminum seal by a new one
- assemble 24mm 6-edge-screw (seal+pipe-screw unit)
- mount plastic air deflector pan
- check oil level
- run engine and check for leaks
- oil pressure between 5 (cold) and 2.5 (hot)
- fixed.

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[rxter]

Dan, will you or shall I ?

"slowly raise engine speed by opening
throttle (with your right arm) until
moaning noise becomes audible"

That's what she .....

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[mefforddk]

Thanks Ryan. I thought it might have something to do with a pressure valve in the oil system. I am not too familiar with the oil cooler system, so I figured someone on the 968 site might have some idea. I'll try to work on it over the Christmas break and report the results.

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[Ryan]

Looks to be a cheap fix.

rxter...with all that vibrating and pullsing and moaning, I knew someone would have to chime in there. [img]style_emoticons/<#EMO_DIR#>/blush.gif[/img]

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