DIY oil catch can?

[boostjunkie]

Well, I'm tired of removing my intake and finding oil up in there. Found this on the Internet. Any idea whether it would be effective?

http://www.tgilmore.com/talon/catchcan.html

[magnux]

I see no reason why it wouldn't work..

[vrg3]

I was gonna try that too... Bought a nice Purolator clear glass filter with replaceable element too (now in the Parts Shed). It looks like on our cars we'd want to splice it in where the PCV hose connects to the elbow going to the compressor inlet, since that's the only place crankcase oil can get into the turbo and intercooler. It should be okay to let the oil into the PCV valve, right?

[boostjunkie]

It looks like on our cars we'd want to splice it in where the PCV hose connects to the elbow going to the compressor inlet, since that's the only place crankcase oil can get into the turbo and intercooler.

I took a look at my engine just now. So you're talkin about those two hoses that attach to the long dual-entry plastic piece that fits into the rubberelbow, correct? If so, then I'd have to rig the filter from that piece into the elbow. Kinda tricky.

What if you placed a filter inline on each of the valve breather hoses instead? If I set it up so that the filters were mounted vertically, instead of horizontally (like the website shows), I would imagine the filters would catch the suspended oil, and then allow it to drain back into the heads when the engine is shut off.

Or am I totally missing the idea here?

[vrg3]

Yes, I'm talking about that awkward joint. You're right that it would be tricky... I was initially thinking of using two 90-degree elbows there to lead to the remote filter. But then I thought it might be simplest to get some copper or thin-wall aluminum tubing and use a tube cutter and tube bender to make a replacement for that plastic piece, shaped appropriately.

Putting one filter on each side might work; you'd just have to be careful about figuring out which line is which because some of them only carry fresh air into the heads, which aren't the ones we care about. I don't know if you'll find more room there than up where I was talking about anyway.

[ciper]

Good idea. I think that it isnt the right choice for filter though. The fuel filter (if designed well) should allow only very small particles through. I think the oil (with its larger particles) would clog the filter and prevent suction to the crank case.

[vrg3]

Well, yeah, it'll get clogged, but that's why you use an easily replaced filter element.

Or are you saying it'll clog up, like, immediately?

If you put it where I was initially suggesting, even if the filter is clogged PCV will work right when the manifold is under vacuum.

[ciper]

I think it would clog right away and cause a postive pressure in the crank which would make oil leak out of everywhere.

[Nigel]

I have an oil-air separator in my Legacy. I used a piece of 3" diameter PCV tubing caped at both ends and filled with stainless steel scouring pads. There's an input fitting on the side near the bottom and an output fitting on the top. I put a drain plug from an air compressor on the bottom. The output goes directly to the PCV valve. I forget where exactly I hooked up the input. I'll have to check. Anyway, I was amazed at how much crap it filters out. I drain it every oil change.

I'm going to make another because this one is too big and the fittings are starting to come loose (tried JB Welding them on but it's not holding up). The fuel filter idea looks interesting, but from the amount that I've drained out of my current filter, I think it would fill that up pretty quick. And I'd be worried about it draining into the intake or back into the crank case. The other issue with that fuel filter is the size of the hose fittings. The stock hoses are 1/2" and that fuel filter uses 5/16". I'm not sure if there would be a flow restriction or if that would even be an issue.

Nigel
'94 Legacy Turbo
'73 Datsun 240Z Turbo

[TireIron]

why not run a catch can that vents to atmosphere? http://store.summitracing.com/product.a ... htype=ecat put that on and seal off the connector to the intake. unless theres some reason the intake air needs gasses from the crank case into it.

[Nigel]

Well, it's my understanding that a vacuum in the crank case helps the rings seal better, and even with a filter on those breather tanks, they can still be messy. Some oily vapour will get vented into the engine bay and the fumes can get sucked into the car interior. I have friends whose Datsuns don't have PVC systems hooked up, and the smell can be horrible. Having driven an older car, I have come to appreciate the emmisions systems on newer cars. There's nothing worse than driving a rolling gas chamber!


Nigel
'94 Legacy Turbo
'73 Datsun 240Z Turbo

[ciper]

Atmoshpere venting units suck. You end up with a big mess, pressure builds up in the crank leading to leaks elsewhere and the air that does escape still has some oil that coats everything.