Crank case pressure

[FFRSpec72]

Past few race weekends I have had traces of oil on the back of my car, seems that oil is being blown up the dip stick tube and then down the outside of the tube and then down to 4" tube and all the way to back of my car.

Any one else have/had dip stick issues and oil being pushed up the tube? What is best way to solve (as when at the track I just ran tape around so it, but that makes it hard to check oil)?

[Bob Cowan]

I'v had the same problem for years. I tried a crankcase vacuum pump. But that sucked the oil out and sprayed it everythwere - what mess that was.

I tried a screw in style dipstick from Lokar. That worked pretty good, but caused the front cover to crack.

Now I just wrap the stick with duct tape. I have to do it 4 times a day, because I check the oil between every session.

[skullandbones]

FFRSpec72,
Wouldn't it be better to find out what the root cause is? I see that guys are doing whatever work around they can to continue racing but what is it that you guys do differently than others with the 302. I haven't heard of this problem with the small block. Do you think it could be just the way you run the engine very hard and most people don't except for short bursts? I was thinking of windage, the type of rings that are used but don't really know if there is a common thread. WEK.

[mhoward1]

While most seem to not havr this problem, I have now heard of a few that now have it with the upgrades. I wonder if it a side effect of the extra RPM now run.

[johngeorge]

Tony, how do you vent now? where does the PCV get hooked up to? Do you have the valve covers vented?

Mark Dougherty added the following to my car when I had it at his shop before MidOhio, seems to be ok (going to a catch can):
http://www.johngeorgeracing.com/gallery/albums/midohioaug2012/DSC00111.sized.jpg

http://www.johngeorgeracing.com/gallery/albums/midohioaug2012/DSC00113.sized.jpg

[tirod]

It's a function of ring seal to keep the gases from getting into the crankcase. That's the only source. Even with leak downs in the 5% range, it's going to happen at higher rpms in sustained racing. Shelby had tall vents on the valve covers, and there are lots of other things done over the years to address it, including vent lines siphoning into the headers, etc.

More venting and a catch can are good answers. Blowing oil out the dip stick tube is just a symptom, not the problem. The issue is not enough venting, and the answer a collection system baffled sufficiently to exhaust pressure, but not the oil. If it's coming out the dipstick tube, the engine lacks sufficient venting. Sealing the tube doesn't fix it, it only seals up the engine even more, leading to pressure build up in the motor, and the next weak link becomes the vent - like, the crank seals.

The motor will vent, choose where you prefer it do that, rather than trying to seal it up and make things worse.

[FFRSpec72]

Tony, how do you vent now? where does the PCV get hooked up to? Do you have the valve covers vented?

Mark Dougherty added the following to my car when I had it at his shop before MidOhio, seems to be ok (going to a catch can):


So I'm just running the 1 valve cover vent that I have run to a catch can, and I have the PCV hooked up to the upper manifold, just the singe line to PCV.

[Bob Cowan]

I have -10 lines routed from the valve covers to a catch can via an air/oil seperater. For the vast majority of the driving I do, this works just fine. It's those continuous high rpm blasts on the track that cause a small problem.

I have seen a plan to use an electric crank case fan/pump. I'm considering it. The belt driven pump simply moved too much air, even with a big wheel and small mandrel.

[Mark Dougherty]

I have run into this for the last 20 years.

The breather system I have on Johns car is due to Nasa requring all breathers going to a catch tank.
As for the dip stick, I have had the most issues with the side mounted tube. It seems that once you get the car dialed in enough to really corner hard the engine will stack the oil in the pan under hard acceleration forcing it out the dipstick tube on hard right hand turns.

I cure this by using a piece of rubber fuel line pushed over dip stick tube and plugged.
I then put the dip stick on a new holder on the radiator.

[FFRSpec72]

I cure this by using a piece of rubber fuel line pushed over dip stick tube and plugged.
I then put the dip stick on a new holder on the radiator.

I'm going to try this for this weekends race and see how it goes, thanks much

[FFRSpec72]

So that woked for this weekend, no to see if I can reduce the pressure so as not to blow the seals

[tirod]

I see how cornering forces can be an issue. We're using a passenger car dipstick in a racing mode, same as using a race car part in passenger car mode. Doesn't necessarily cross over.

NASCAR is probably no help, they just stick the other side of the motor. I do see some motors using a screw down stick, threaded into the tube. Briggs, for instance. People tip them over all the time to service the deck, can't have oil running out.

Maybe the same thing could apply.

Yes, just found it: Copy for an web page selling Milodon pans: "A sealed, dirt proof, screw in style dipstick".

It's out there.