ltbrkm3

clog and pull oil into the intake manifold???
TIA
Scott

JasonAndreas

No, the 964 does not have a positive crankcase ventilation valve but if you add one it's good for a documented 5HP (1st image). On top of the crankcase there is a condensation dome (1st image) that vents to the oil tank and the oil tank vents to the intake manifold (2nd image - red arrows). So if you overfill the tank with oil it will dump the excess into your intake manifold, gumming up your ISV and throttle body and causing all sorts of odd running issues.

garrett376

Jason - is that your engine showing the Linton part?!

JasonAndreas

with the carbon fiber and gold filmed heat shield, don't I wish...

ltbrkm3

Thanks Jason. I have no runability problems, but after about 6 hours of slow careful work on Sunday, I still have an oil leak from the left rear of the motor and it is neither the lower valve cover, or the cam cover gasket-as I thought it was. I have not checked the upper valve cover, but I'm trying to get an idea of what else would leak from the left rear of the motor from the top. My car is a 61K mile '92 and so in theory, should not have the head gasket problems of some of the older vintage cars. Any ideas??
Scott

Wachuko

Are you sure is motor oil and not steering fluid... just checking as I had a small oil leak that I thought was motor oil and turned out to be one of the steering pump hoses that was a bit loose... worth a look.

dfinnegan

I had the same issue. Mine was the hose on the bottom of the steering fluid reservoir. Although, that's the right rear.

ltbrkm3

Wachuko,
Thanks for the idea! Are there any power steering hoses on the driver's side rear of the motor? Was your oil leak migrating to that side the the engine? I'm willing to try anything at this point as six hours spent cleaning and replacing those two gaskets feels like a total waste now....although the gaskets I replaced were most likely adding to the amount of oil that was leaking. The passenger side of the engine is not leaking at all-thank god!
Scott

JasonAndreas

I think I might have seen a post at one time showing an oil leak from the crankcase condensation dome but the usual suspect is the oil pressure sender on the right side (gold thing with the green wires sticking out of it in the image below). The only thing underneath the black engine cover on the left side that you will find sticking out of the motor is the knock-sensor but that won't leak.

Here is a picture from the rear of a stock engine.

Wachuko

No... only for those leaks coming from the passenger side (on left-hand drive cars).... sorry.

JasonAndreas

Here are some other photos showing what's back there, ignore the red arrows.





There is a cap on the camshaft but...

frankvan

Great engine pics.

I too have a leak somewhere on the left side (drivers side for NA) and it's gummed up all over the CHT sensor and will occassionally (rarely actually) drip onto the hot exhaust manifold producing impressive black smoke from the drivers side rear wheel well (I thought my tire was on fire once!)
But I can't find where its coming from - it might be that dome you mention but the top of the engine appears dry. Replaced the oil sensor o-ring a couple of months ago and that area was clean. Also thought it might be a rocker shaft seal at the end of the last cylinder back there.
Could it be a rear main seal leak that is migrating sideways? (via excessive cornering forces of course )

There is a bit of oil on the passenger/right side but it is more of a dry film rather than a discreet leak and that is probably power steering fluid (notice it needs a top-up of about 100 ml once a year). The one on the left side will leave a quarter size drop on the ground overnight but nothing drips off the right side.

Of course at my mileage that amount of oil drip is negligible and it doesn't seem to need more than a liter every two months / 2000 kms or so.

Frank

DWS964

Tell us more about adding a PCV, and how that can add HP. (I searched the Forum, but nothing came up.)

Heirsh

I think the theory is less dense air in the crankcase leads to less air molecules smacking moving parts in the engine, and therefore less parasitic losses from the engine.

JasonAndreas

I believe Porsche started using them on the 996RSR, here is a better explanation then I could give,

Here are some photos of the 1-way breather valve for the 996 from PMNA. There were some prototypes made for the 964 but nothing is available commercially that I know of.










You will never, ever, ever see me tell someone to use the search function.