DIY Oil Separator/Catch Can
 

This post should probably be titled: "Poor man's Oil controls" Anyway, here goes... After various failed attempts to eliminate intake/plenum oil ingestion and find a solution for high RPM crank case pressures, I thought I'd share my luck with a "cheap" solution found at your local neighborhood Home Depot (please hold all chuckles at this time).

My objective: Eliminate all oil from the intake plenums, maintain a crankcase vacuum, and vent excess crank pressure at High RPM's. Not an impossible task, but difficult with all the oil misting that goes on with these engines. And from what I've seen, all the solutions out there cost big $$$.

My discovery: Using a simple (small) $11 air compressor oil/water separator, and placing it "in-line" with stock cam cover vent hoses, I was able to capture and eliminate about 75% of the oil that would find it's way into the intake plenums and base of the throttle body! Not bad for a cheap experiment, but I knew there was some room for improvement there. Plus I suspected High RPM CC pressures were partly responsible.

After going back to Home Depot for the Larger $22 separator, I was ready to try re-routing the crank vent hoses on the passenger side cam covers and base of the oil filler neck. This time I actually got some good results. Only a small trace of oil was found in the intake plenums after several miles of hard driving while a very LARGE amount, however, was caught in the separator. Not wanting to worry about the possibility of overflow going forward, I still had one more experiment to try.

For $53, I purchased a JAZ mini catch/breather can to route the passenger side cam cover and oil filler neck hoses. This would then give me flexibility to vent high crank pressure, capture more oil while devote the Oil separator to pulling a vacuum on the crank case and deal with "misting". The results? After 100 miles of spirited driving I have yet to find ANY trace of oil in the intake plenums!!!:rockon: I also noticed that my persistant (small) oil leak has stopped too. Overall, I'm very pleased with the "poor man's" 928 oil control system.

nice, I may try it

You might also want to look at the ProVent air/oil separator on our website - about $138, and very effective.

i would at the VERY LEAST remove those stickers on the front that say "husky"

I wouldnt want any Home Depot stuff in my engine bay, but thats just me.

I installed the HD 'Huskey' unit on my 951 2 years ago(after removing the advertising) and it works great. The intake stays clean.

with the JAZ minicatch/vent I can tell you that you are letting teh crankcase breath prett freely at that too. This subsiquently is allowing unmetered air into the engine. But I do like the idea of the water/oil air seperator that is a very very good idea, that I may implement on the vent line to my air oil seperator. That is if I use it any more without putting the drysump setup on first.

Sliceolator,

Very nice! Wonderful ingenuity! Who cares that it says Husky, I applaud your efforts. Thanks for the great post.

Dan

+1 on Colin's comment about unmetered air. Depending on how much blowby you have it may or may not be an issue. If you can check your AFR before the cats, try pinching off that line at various RPMs and see if it leans the AFR enough to be concerned about. It may not be enough air at idle to affect the idle much, but at higher RPMs it may pump a significant amount of unmetered air into the manifold. The line really ought to be attached to the airbox ahead of the MAF.

Where does the unmetered air come from? From the catch can to oil filler neck, then into the intake through the oil/air separator? What would be the drawbacks of eliminating the low rpm crank case ventilation circuit?
Thanks.

Tony

Just dump it all over board. I have yet to see any significant oil out of my seperator drain line...if any any

I have a 1 inch line coming from my oil filelr neck/seperator....that runs into 2 stock 1/2 inch lines from the cam covers....then this 1 inch line goes to my home made seperator....then dumps into the driver side exhaust stream aft of the cats though a one way check valve.

the bigger you can make the lines the better.

Tony, do you have any pics to share? Sounds like an interesting setup.

Nice product there Wally.

And Slice, nice setup too!

I love this forum!

Ed

Blow-by past the rings will get fed into the intake manifold. There are those who say that there are benefits to having the crankcase under vacuum, but IMHO this is best done on a fresh engine and/or where you can tune to compensate for the extra air.

Wally, is there an installation diagram anywhere for connecting the ProVent on the 928?

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

Hi Dan,

I'm not Wally, but I can help you with that. Here is a link to the ProVent Spec document that describes how it works and has generic schematics for proper installation. http://www.928gt.com/productspecs/ProVent1.pdf

If you need help with installing one in your 928, feel free to give me a call at the office and I would be glad to guide you thru some options specific to your setup.

How is that happening?