RSAErick

Hi all!

During my last track day, I discovered a nasty oil drip directly in front of the right rear tire. Not cool. Inspection of the area (wheel well) revealed oil everywhere, making it very difficult to determine where the oil leak was coming from. My best guess was that the leak was coming from the two small oil lines circled in my picture (#26 and #30) on the diagram.

After replacing those two oil lines, all was well. There was no leak whatsoever during weeks of street driving.

However, my next track day resulted in the same problem - oil leaking from the front of the right rear tire, and again sprayed all over the inside of the wheel well. Apparently I didn't replace the leaking oil lines. And now I'm having a very difficult time finding this pesky leak.

Well, I obviously can't expect anyone to find my leak by looking at pictures. So, I suspect that I should begin by removing the oil tank so that I can inspect it and all of the lines that are mostly inaccessible behind the tank.

But I'm embarrassed to say that I can't figure out how to remove the tank! I removed the nuts that hold the tank to the rubber bushings (#2 and #3 on the diagram), but the tank still feels secured to something.

So, here are my questions:
1) Are there any good ways to find an oil leak, when the oil leak only appears during track driving (and at which point the oil gets sprayed all over a multitude of potentially offending oil lines)?

2) How does one remove the oil tank?

Thanks as usual for the expertise and advice.

JasonAndreas

I don't know if I would be so quick to pull the oil tank out, there are no openings that you can't already see with it in place, as is. The two that are slightly difficult to see are on the bottom, you have #21 which runs to the thermostat (and eventually to the two hard lines in the front) and #22 that runs to the drain plug. Have you checked the pressure release valve on the top of the tank? In your picture the two breather lines up top look clean but the dipstick and filler lines look caked in oil. I'd clean everything up, remove the "shark fin" so you can see the thermostat and go for a drive. Maybe even pull the fuse for the CCU so the oil cooler fan won't run properly and try to get the oil temperature and pressure up high so that the oil level in the tank rises high enough to reach the upper hoses? The good thing about those rubber oil lines is that if they leak you can just loosen the clamp, move the clamp .15" and retighten and they won't leak for another 5 years.

ChrisD

I have just had a similar problem and found that it was the filter to thermostat line that was leaking. It was weeping from the join of the braided section to the hard section that connects to the thermostat, (although looking at your pic I think this line has been replaced before?). Initially it was difficult to see where the leak was, so I took off the side sill and drove it for a little while, I then could see the offending area!! I have now removed the line from the filter and removed the tank completely. Once you can get the large nut free on that oil line, the rest is fairly simple. Don't know if you can get acces to the tank supports with the large oil line in place. The securing bolts on mine were jammed solid and I had to cut them off to free it.

I am glad I got the tank out, as there were several areas of rust forming on the tank and a load of crud up in the wheel well.

Good luck!

LA964RS

Same as previous post. Do a search of the forum on this one. Also a good tech article on Pelican. Common and you can...on a long weekend, replace it yourself w/the right tools and patients.

Good luck, you'll be happy when its fixed and it quits leaking...makes a mess.

RSAErick

Ok, you've talked me out of it! At least for now.

Thanks Jason. I'm really curious about the pressure release valve. Is that #44, #45, and #59? The reason I ask, is that I can barely see that curved tube(#44) on top of the tank, but it looks well-doused in oil. Will this valve leak oil? When/why? Does the pressure relief valve release pressure when RPM's cause the pressure to rise? If it fails, could this cause oil pressure to go too high with high RPM's? It looks difficult to reach without removing the tank.

I suspect that the leak is from one of the 'upper' oil lines, because oil appears so high up on the front side of the wheel well. If the oil leak was down low, I wouldn't think that the mess would appear so high up, or maybe it would apear more on the back side of the wheel well, where the tire kicked it up. But I could be wrong about that.

Thanks!

RSAErick

Thanks Chris. I'll clean things up real good (again) and give it a good drive to see if I can see any leaks. It really only seems to leak after a good 20 minute track session with high RPM's and high heat, so I wonder if I'll be able to see anything without raising the concerns of the local authorities.

DarrylH

Just spitballin' here, but - no chance you're just a bit overfilled with oil, and the expansion due to track temps (and the sloshing) pops the vent? Or maybe the vent just isn't working correctly. It's supposed to open at 180 plus/minus 20 mbar, which is about 3 psi. Dunno how you'd test the valve, but if your cleanup shows it's the culprit, and it's not too expen$ive...

RSAErick

That is a possibility, I guess. I usually get the oil level into the middle of the gauge when the car is at street temperature. And I NEVER use the dipstick, becuase I find it difficult to read.

Is a properly functioning oil tank pressure valve intended to release oil with expansion/overfill?

Thanks for the idea!

DarrylH

To quote Adrian Streather over on Smartgroups (I hope he doesn't mind): "Too much oil will cause an over pressure and there are three over pressure relief valves. The excess oil in this situation is sprayed everywhere outside of the crankcase or the oil tank." (The other two valves are on the engine, one on each crankcase half. I don't have to hand at what pressure they release, maybe someone else knows?) So I don't know if this is your problem, but if the hoses and lines themselves appear OK, and it's coming from the top of the tank, and only under circumstances of high temp (high volume) and high RPM (high oil pressure) it seems at least possible...

RSAErick

I agree, that seems possible. Thanks.

JasonAndreas

I would think it should only dump oil on an overpressure situation, when I overfilled I had oil dump into the intake manifold on both sides of the throttle body but nothing externally.
My 964 is up in the air so I just wrapped a paper towel around a screwdriver and shoved it into the little U-shaped hose on the upper pressure release valve and it came back clean and I didn't have to remove any hoses to reach it but it was tight. If you take the two upper rubber breather hoses off the tank you shouldn't have a problem reaching the hose clamp #45 that holds the U-hose #44 over the pressure release valve #59 so that you could take a better look.

The vertical relief valve opens at 6.2 +- 0.8 bar but it doesn't vent to atmosphere, only into the crankcase and I believe bypassing the oil pump? The horizontal relief valve opens at 8.0 bar.

LA964RS

I couldn't see my leak. up on the top where the oil line goes through the hold down...it chafs and then leaks. It more like sweats. I never saw it coming out as it came from behind and then leaked down towards the bottom . I jacked up the car and removed the rr tire and ran the car after washing it down w/simple green. Of course did it when it was hot and the thermostat was open to make sure it was on full operation.

Good luck...I'd guess not an overfill issue, but a hose issue.

RSAErick

OK, I found my oil leak by cleaning it up, warming it, and driving it like I stole it for a while. Here is the result:



Although you can't specifically see it in the pictures, the leak appears to be coming from the breather tube (#44) located at the top of the tank - where it opens downward.

The next question is WHY??? I don't think that I've overfilled the tank because there's no oil topside in the engine compartment, and my oil level appears fine. I checked the level via the dipstick (which I hate trying to read), and the oil gauge here:



Actually, I even found a second small small leak. The hose coming from the bottom of the tank has a small crack that is seeping or weeping oil. Fortunately, THAT will be an easy fix:



SO, my questions are:

1) Why is it leaking at the breather valve?

2) Will a new breather valve fix the problem?

3) How do you take the oil tank out to get at it? The only two connections that I can see are here:



and here:



But when I loosen those, the tank doesn't budge. I must be missing something!

Thanks once again!!!

JasonAndreas

You either have an overpressure situation or did at one time and the valve is sticking open (could be a one-use valve?) You should be able to remove it without removing the tank, your supposed to just grab it with a pair of pliers.

Have you had the tank removed previously because the oil line that runs from the filter console to the tank is not factory?

RSAErick

Hmmm, I wonder what might cause an overpressure? OK, I'll remove the oil line is front of the pressure release valve and try to access it from there. Just pliers, huh?

I don't know. I'm sure that it hasn't been removed since 2002, though.

Anyway, I'll be thankful if a new pressure relief valve fixes my problem. Thanks for the advice.