Oil dripping out of the wiring harness

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GZig
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Post Sat Aug 02, 2014 12:51 am

I noticed a pool of oil under the car and when I looked to see where it was coming from i saw it dripping out of the wiring harness under the intake manifold. There seems to be a plastic tube amongst the wires in the harness. Is there a tube which goes from the engine through the firewall to some kind of oil pressure gauge? I do not have any kind of physical pressure gauge inside the car that I know of!
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Post Sat Aug 02, 2014 1:36 am

Hello and welcome to the Zone...

Which engine is it ?
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GZig
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Post Sat Aug 02, 2014 1:59 am

My car is a 1987 325i which has the M20 engine
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Post Sat Aug 02, 2014 3:31 am

Oil will cling to wiring,then dribble off at the lowest point.

On the inlet side of the M20,most leaks can be traced to the crankcase breather,that tube thingy that runs from the underside of the inlet manifold to the crankcase.There's an O ring top and bottom,or there should be an O ring top and bottom...

The rocker cover rarely dribbles on the inlet side,as this is higher than the exhaust side,and gravity does have an effect!
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GZig
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Post Sat Aug 02, 2014 4:42 am

That was my initial thought. I replaced those o ring a couple of years ago when I had the intake manifold off to inspect and clean the injectors. When I saw oil dripping from the wiring harness I looked all around the valve cover thinking the oil may be coming from there and running down the harness and no leaks. With the engine running you can see the oil coming out from the inside of the harness.
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Post Sat Aug 02, 2014 12:23 pm

Check the oil pressure switch on the oil filter housing. The switch failing can cause this issue as the oil is forced up the conduit that shrouds the sensor wire.
Pull the plug off the switch and if oil drips out, there is your problem.
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Brianmoooore
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Post Sat Aug 02, 2014 1:56 pm

pacerpete wrote:Check the oil pressure switch on the oil filter housing. The switch failing can cause this issue as the oil is forced up the conduit that shrouds the sensor wire.
Pull the plug off the switch and if oil drips out, there is your problem.
That was my first thought when I read this thread, but the OP says the drip is on the inlet side. I've never known oil from the pressure switch to make it to the other side of the engine.
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GZig
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Post Mon Aug 04, 2014 1:54 am

I did disconnect the OP sensor wire and oil did come out of the plug and tube which the wire is in. I guess there was enough pressure to push the oil up the tube and over to the other side where the wire goes into the main harness where there must be a break in the tube where the was coming from. Thanks for your input.
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Brianmoooore
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Post Mon Aug 04, 2014 10:08 am

So it can make it to the other side of the engine then!
New oil pressure switch required. There are two types for the M20, depending on date, and yours is around the change over time. Early type just has a nut to connect a single wire, and the later type has a proper two pin plug (although only single pin fitted).