Diagnose fluid leak

[Batoutahell]

I could use some help diagnosing a fluid leak. I'm pretty sure it's oil, but based on the location of the leak, and the road grime contaminating the fluid, I'm not absolutely ruling out another fluid. It seems to be dripping onto the driver's end of the rear subframe, just in front of where the rear trailing arm attaches. The fluid is concentrated on the rear driver's jackstand point.

I haven't notice much if any oil loss on the dipstick. What oil/fluid source would drip onto that area? Everything looks dry from above, although I haven't removed the air box yet to get a better look. From below the transmission case looks dry. My brake fluid reservoir is lower than I'd expect after a weekend at VIR. Could I have a leak in the brake line?

 

[ak]

can't see pic

 

[Larry Bastanza]

Check your clutch reservoir. Could be the clutch slave

Regards,
LarryB

 

[Batoutahell]

Sorry about the red x's, my usual pic hosting service has been down lately, and I haven't figured out how to link to pics that I uploaded to Prime.

Larry that's brilliant, I never gave the clutch slave a second thought. I will check the clutch reservoir and the slave tonight!: smile:

 

[Batoutahell]

Ok, the fluid I'm dripping is oil. I removed the air box and found oil pooled in the bottom of the air box and soaking part of the unifilter element. There was also some oil in the intake duct just in front of the TB. The oil that had pooled in the intake box was, on hard right hand turns, draining down towards the intake scoop.

I've been reading up on the pcv system, and some members have hypothesized that the baffles in the valve cover on the rear bank (on 3.0L engines) don't allow oil to drain efficiently out of the head. Some also theorize that this is the reason why our cars appear to lose oil pressure during extended periods in vtec, because oil is accumulating in the heads. Some believe that oil can accumulate in the rear bank, and that given the position of the breather tube as it connects to the rear head at the rear drivers-side corner, that oil can get slung into the breather tube.

This hypothesis definitely fits my sympotoms. More than 1 person on track commented that the only place where I would puff smoke out my exhaust was on the front straight going around the bend at start/finish. It's a fast (135mph), long, right-hand sweeper. In that turn, any oil in the rear bank would definitely be accumulating at the rear drivers side corner, right where the breather tube attaches.

That's my hypothesis at this point. I'll be ordering a new air filter, as I'm not sure it's wise to re-use my unifilter that was partially soaked with oil, and cleaning out my TB. I'll also check compression this weekend just to cover my bases. Any other ideas?

 

[ak]

Do you have any mods? FI? I've ran VIR many times and never had oil problem like that before but my car is NA. Also, I've had puddle of oil in my airbox with unifilter before due to overoiling of the filter after cleaning, though in your case it seems like it was real oil. I'd just clean the filter and re-use it.

 

[Larry Bastanza]

My next question is along the line of ak's. So let's start my what do you have under the hood?

Year
Age
Mileage
Mods

This really does not sound like a leak, but rather too much crankcase pressure.

HTH,
LarryB

 

[Batoutahell]

It's a '91, n/a, 60k miles, i/h/e, short gears, final drive, r suspension, r comps.

The oil in the air box is definitely engine oil. I've put 4-5k miles on the car since I bought it 2 years ago, and I haven't oiled the filter. I did have the filter removed a few months ago, and the air box and intake duct in front of the TB were dry at that time.

What would you suggest to clean the filter, just the uni- cleaner kit? I would have assumed that engine oil would contaminate the foam, but that's just a hunch.

Right now it seems to me like either a crankcase pressure issue, or oil sloshing up the breather tube, or a little of both.

 

[Larry Bastanza]

I really think after you check/replace your PCV valve, it may be time for a leak-down test.

Regards,
LarryB

 

[Batoutahell]

A new unifilter is on order. I can see how a stuck pcv could lead to increased crankcase pressure, which could in turn lead to oil spurting up the breather tube. My pcv valve doesn't quite seal perfectly, but it does open freely. Soaking in carb cleaner didn't affect the pcv.

I found the video footage of a car following me at VIR. Here's the link: http://youtube.com/watch?v=QeRVoTRFPCQ. At 1:30 in the video you can see the puff of smoke coming from my car as I round the bend on the front straight. The car following me drives through the smoke at 1:32.

I'll try to do compression and leakdown tests this weekend.