amr89c4

Hi guys,

I have an oil leak. Ok, you can stop laughing now!

I have addressed the usual culprits, timing cover gaskets, valve covers, oil bridge O rings and the chain tension adjuster cover gaskets. The engine runs dry as a bone at normal hiway speeds. However, pulling sustained hi rpm at the DE's, downshifting etc and the general running hard for 24 minutes causes a film of oil to deposit on the rear bumper. Then when you look under the car you can see a few drops developing under and around the timing the bottom of chain cover boxes and chain tensioner covers .

I was hoping I might have a crankcase breathing issue instead of a leak at the cam seal gasket or O ring or the timing box gasket that interfaces with the block. Its leaking on both sides of the engine in what appears to be equal amounts.

The PET shows a lot of different valves and check valves located in various place on the oil and fuel system. None are described as a PCV valve or crankcase vent valve that I can see. So now I ask the stupid question: Is there a PCV valve or facsimile of one I haven't found yet?

Since I only get the blowby or leak at sustained hi rpm, I thought it could be a venting issue. Not pulling hard at DE's is not an option.

Thanks!

Indycam

Its a dry sump system .
The pump that pulls oil out of the case and sends oil into the oil tank also does the same with air / blowby . The pump does not suck "solid" oil , it "picks up" air also .
The hose that runs from the tank to the intake system ...

I don't know if that helps .

amr89c4

Indycam....Hmmmmm. I saw that vent hose from the tank to the intake. I will take the oil cap off and see if I feel blowby. Of course that could only serve to raise the question of is that normal?

I got a spiffy new hi intensity light today and was able to really see well up between the timing chain boxes and the block and there is zero oil coming from that area on either bank, so thats good news as it rules out the cam gaskets and O rings. That leaves the timing chain case gasket, #7 in PET, part # 930-105-193-06 as a possible culprit if its not a breathing issue.

Overnight, the drips have accumulated on bottom stud of the timing chain box, the timing chain tensioner covers and the last two, rear, bottom studs of the valve covers on both sides. The spots on the garage floor are barely the size of a 50 cent piece, and that just a film from the oil sheeting.

I have a tech inspection (70 miles away) tomorrow which is a non issue as when I clean it up tonight it will not exhibit any sign of a leak at hiway speeds. It will be a mess after the first session at the DE, though. I don't want to be unsafe to fellow drivers or get black flagged either. I don't get any smoke when running, or at least not enoght to get flagged thus far.

Thanks

springer3

How many miles on the engine? A leak-down test might reveal you have leaky rings, and pressure build-up from blow-by is forcing oil past the seals. I have seen this happen on cars that still ran well.

amr89c4

53,000 and the engine runs smooth as silk at idle and pulls hard throughout the range, up to 6800.

I thought the same thing, but dismissed it, perhaps prematurely. I decided that since the oil stays very clean, the spark plugs show no signs of oil blowby and the exhaust is clean, it was probably ok. Oil consumption is 'good' at about a quart per 1200 miles. Consumption is much higher at DE's but that is normal, too. Plus, I think a cylinder problem would at least show some blue smoke on cold startup.

Nontheless, I bought a cylinder differential leakdown compression gauge last week and will run the test when I get a chance.

I wonder if some poorly rev matched downshifts (not missed shifts) could be a part of it? I heel and toe pretty well, but do screw it up from time to time.