Oil loss cannot diagnose 87 924s

kevrobert · 03-31-2016, 06:01 AM

Ok it never rains but it poors as they say I have a leaking rear main which is losing me some oil but not catostrophically.
I am losing a lot of oil the other symptoms I have are fouled plugs which appear to me to have heavy deposits as well as some oil, and a fluctuating temperature which goes down randomly when driven.
Now compression is perfect as you would expect on a 46k motor all 200 psi. Oil pressure is 4.5 cold running and 3.5 hot idle. Engine runs sweet.
Recent top end overhaul new gaskets, exhaust valves and valve stem seals.
Oil and water are clear.

Am i looking at the early symptoms of an oil cooler seal failure or are for some reason my valve stem oil seals kaput although new?

What the hell is going on!

dgcantrell · dgcantrell's Garage

Pull the throttlebody and see if you're getting lots of oil in the intake. If it's that far upstream, it's pulling too much oil vapor from the crankcase. I think the culprit may be the Air/Oil separator seals. You have to remove the intake to get to it though.

mytrplseven · mytrplseven's Garage

I agree. This sounds like AOS oil seals.

kevrobert · 03-31-2016, 11:25 AM

Have a catch tank so no oil in intake, could the AOS be blocked in someway causing excess crankcase pressure?

dgcantrell · dgcantrell's Garage

While I never had any issues with mine, while I had the intake off it a couple of years ago to replace the gaskets (also the gasket on the cam tower), I went ahead and removed the AOS and gave it a bath inside and out. Poured Castrol Super clean into it and cleaned it out pretty well. The seals looked OK but they were original 25+ years old but ordered new seals and a few other items (hoses) and replaced all that under the intake since I was in there. It won't hurt to give it a shot and see if that helps it. If not, it's one less thing to have to worry about later..

Rasta Monsta · Rasta Monsta's Garage

Your RMS leak will decrease if you hook up the breather correctly.

Fast Freddy 944 · Fast Freddy 944's Garage

Porsche and Harley Davidson should be exxon valdez twins, they both leak like sieves! lol, cat litter is the order for the day........ of course if you cant see any leaks, you might have a tired motor, valve guides, seats, piston rings etc.....

kevrobert · 04-10-2016, 06:52 AM

Ok ive renewed the AOS seals I was hopeing to find a blockage or damaged seal but everything was in order, on pulling the manifold i could see the oil pooling on the inlet valves but no evidence of oil coming through valve stems. It appears to me that there is nothing coming out of the AOS breather i have a catch tank with filter and its bone dry in there have also added a vaccum to the oil filler neck, if this is the case why would the pressure not be escaping from the AOS. Is it safe to say having seen the oil pooling in the inlet side on all valves that the exhaust valves are not at fault?
Using as much oil as fuel!

dgcantrell · dgcantrell's Garage

Is there oil in the intake?

kevrobert · 04-10-2016, 09:42 AM

Not in the intake as have a catch can fitted but evident on intake valves, convinced its blow by through pistons but dont understand how ar present.

dgcantrell · dgcantrell's Garage

Have you check the compression on the cylinders? That much blow-by on the rings would definitely cause compression issues. But how the oil is pooling on top of the intake valves doesn't make sense. The only time the intake valve is open is on the intake stroke, there for any oil in the cylinder is not going to be able to escape due to the air flow alone. The oil has to be coming from upstream of the intake valves.

djnolan · djnolan's Garage

"Your RMS leak will decrease if you hook up the breather correctly."

Is it possible you have the AOS and ICV lines connected incorrectly? If something was incorrect, it might suck oil, through the throttle body, but I don't know how it could even idle. Just a thought.

kevrobert · 04-10-2016, 10:32 PM

I ported the head and an wondering if there are pin holes allowing oil through when hot? Although looking at the design of the head it looks like the water jackets are closet to the valve ports?? I will have to check the exhaust side next..still a mystery at present

dgcantrell · dgcantrell's Garage

Nope.. The oil galleys are not that close to the ports. Water jacket, yes. Oil, no. Obviously the car smokes when it's running. Could just be the valve seals have gone brittle and leaking like a sieve..

kevrobert · 04-11-2016, 01:55 PM

Found this photo online port very thin where yellow mark is I bet this is the problem...

kevrobert · 04-11-2016, 02:06 PM

Amazingly it dosent smoke much and nothing when warmed up i must have the equivalent of the only diesel powered 944 😕

dgcantrell · dgcantrell's Garage

Just how aggressively did you port those things.. LOL. You could be right though. But if it's dripping that much oil on the valve, you may able to see a trail of sorts. The oil from that part of the head would not be under pressure though.

kevrobert · 04-12-2016, 10:46 AM

Cant see a trail reckoning on pin holes only leaking under heat and pressure, guess i was bit to aggressive untill i can rework another head i am going to use a special loctite epoxy weld , pull thermostat and add a breather line via the allen cam plugs 😏 hopefully last till a reworked head is configured... Just bought a complete top end for £62 on ebay!