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A recent vehicle inspection noted a slight oil leak coming off the engine crankcase. (Moistened, not dripping.)
I figured it was probably the oil pressure + temperature sensor plug's o-ring (39mm diameter) needed replacing, again. [Did that for the first time about 9 years ago, solved THAT timeline's leak, so figured the o-ring had hardened, again, and was leaking, again.
Got in there (see picture) and found the oil sensors plug-in looking dry.
Instead, it looks like the oil breather lid's port "C" is wide open. This is also obviously the source of the leak, I believe.
BTW, the "1/93" O.E. breather hose is still pliable.
The parts list shows going into this open, threaded port a "thermal switch", or some such.
Couple questions come to mind:
1) What's this thermal switch do? (Car has seemingly run fine without it.)
2) Is there supposed to be an electrical lead going to it? (One doesn't seem obvious in my first reconnoiter.)
The car is a WPOAB2968PSxxxxxx (US C2) manufactured in March '93. 120k miles. I've owned and maintained this car since '06.
PS, I'd already procured the oil sensor (A+B) plug's 39mm o-ring, so will be replacing that, regardless.
3) Should I leave sleeping dogs lie with regards to prophetically replacing the breather lid's gasket, too?
The A & B oil sensors are working fine at this time. And are seemingly original items.
My car doesn't have a sensor their either. I checked PET and the temp sensor is only used on the M64.50 (turbo) engines.
I would not touch your A&B sensors they appear to be dry and fine as is. Have you tried taking a photo of the opposite side of the engine? Maybe there is a leak source on the other side.
The breather vent cover doesn't have any significant pressure on it, so I would be surprised if that is the source of the leak.
Rob, I haven't removed the left-side intake manifold, only the right. So, pics on that side will likely be tough, though I'll give it a try tonight.
Can the left manifold be removed while leaving the crossover plenum (& its related junk) left hanging in place?
Or does EVERYTHING have to come out? (I hope not!)
So C's a non-drilled thru port, huh? Go figure.
Perhaps one of the four breather lid's hold down nuts has loosened?
The way I was 'reading' oil leakage signs, from the wavy waves of dirt coming down the near side of the lid, it looked to be coming off that now-discounted hole. Perhaps that breather hose has been pinch-cut? Will have to take closer looks.
Pelican has breather lid gaskets in three flavors: "Porsche" $15, "OEM" $10, and "OE manufacturer" $5.
All three look like gasket cardboard to my eye.
Here's a similar themed thread. It wouldn't hurt to put a wrench on the 4 10mm nuts to make sure the breather cover is secure. My bet is that your hose is starting to weep.
My breather hose looked fine as well from outside. Close inspection inside of hose revealed a crack under the clamp. That, according to tech, was source of leak.
A picture or two for you. Maybe this helps. This was when I was building the motor back up. I had already replaced that breather housing seal before, where I removed the whole intake manifold for access and replaced all the rubber bits and misc. (hoses, intake boots, vacuum connectors, fuel regulator, etc.) Don't get distracted by that vacuum line in the photo. It finds its home later. : )
Also, it is possible for the FPR to leak out the side with the vacuum connection and make a mess on the front of that breather housing....
I seem to remember you need the space to pull the FPR off and fuel lines out of the way to get that breather housing off...and that was one reason to remove the whole intake manifold.
If you go in there, I would certainly replace all those bits if they have not been done, or you will be in there again. Ask me how I know that !!
11-06-2017, 11:14 AM
Breather Lid "thermal switch" port?
This is also obviously the source of the leak, I believe.
