Oil Catch Tank

[Doug D.]

Anybody here ever use an oil catch tank on a veedub motor? Typically, they're used on high compression/high performance engines to catch and separate oil mist from crank case gasses before they are recirculated back to the intake through the PCV circuit.

My engine has an aftermarket oil filler with a port for routing a tube from same back to the intake, in my case, the bottom of the air cleaner. My engine has always puked a little oil out of this port no matter which way I turn it. I used to run a tube to the intake, but got tired of cleaning excess oil out of my air cleaner and carb. I replaced the tube with a simple breather filter to keep the carb clean, but now I have the mess of an oil drip out of the breather.

Compression, blow-by and leak down tests all come back well within specs, so barring any additional information, I've tentatively ruled out an engine problem as the cause of the drip. I was once told by a "buggy guy" that this drip is normal and most folks just run a hose from the port and let the oil hit the ground. I suppose that's ok, if you like scrubbing the garage floor every other weekend.

So back to these tanks... I've found a ton of variations on the net, but they all basically look like this;



There's an "in" port and an "out" port, and the better ones have a sight gauge for monitoring oil level in the tank, removable end caps for cleaning, and are equipped with a down tube on the "in" side to direct the gasses and oil mist to the bottom of the device, and a baffle to separate the gasses and mist. PCV gasses and atomized oil pass through the tank. The separated oil collects in the bottom of the tank and the gasses are routed back to the intake as previously stated.

While I see these tanks, in my case anyway, as a band-aid solution for what I pray isn't a bigger problem, they present a solution for an annoying mess. They range in price from less than $40 to a couple hundred, depending on how much you want to spend on a "name brand".
I've found a couple cheaper units on the very low end with end caps that would allow the user to add their own down tube and baffle.

Any thoughts on the use of such a device, or as to other causes of the drip?

As always, thanks in advance and ride safe!

Oh, and here's a link on the subject that I thought was interesting;

http://oilcatchcan.com/

 

[vw driver]

You could get an original VW oil bath air cleaner. They have a port for the crankcase vent hose. Of course they are really big and clunky looking for a trike where people can see the engine. I don't think I've ever seen a trike with one. Most of the ACVW engines I see drip a little oil here and there from different areas of the engine. Of course I see a lot of other vehicles that leak some oil also, go look at the oil spots in any parking lot, they are not all made by VWs. At least we are not leaking anti-freeze all over the place.:laugh: The catch cans look like a good idea to me.

 

[Doug D.]

You could get an original VW oil bath air cleaner. They have a port for the crankcase vent hose.

Hey vw driver, thanks for the response.

I thought about the oil bath air cleaner when I put the trike back together originally, but I changed over to a Weber 2 bbl carb, so the stock unit won't fit anymore. The air cleaner on the Weber has a port for routing the gasses back to the intake, but then I'm back to dumping all that crap into the intake.

Even though everything seems to check out, I still have the lingering thought that there may be a problem with the engine because of the amount of oil vented through the port. It could be the aftermarket filler neck or something else, but I can't seem to figure out what's up.

While the bug motors seem to leak as a rule (part of their charm ), this isn't so much a leak as it is a "PCV" problem. That makes it all the more puzzling, as the "PCV System" on these motors is little more than a puker hose going back to the air cleaner.

 

[vw driver]

My '71 bus (dual port engine) has a port on the left side intake manifold for the vacuum assisted brakes. If you could find one of those maybe you could run a hose from the crankcase vent to that port which would feed the blow-by directly into the intake manifold. I guess you could drill and tap one of your intake manifolds and create a port with some kind of screw in fitting. I don't know if doing this would cause the plugs to foul on that side, I guess the only way to find out is to try it.ThumbUp

 

[slick rick]

Guys I'm having to learn a lot about these engines but I have a type 3 and honestly it has no more than a drip every once in a while , uses no oil between changes . I don't know if it's just a good one or the type3 operates a little different or it being a stock engine it doesn't do it .

 

[Loner]

As you have noted in your first post, you are addressing a bandaid and not the source problem (and I fully agree that it is the best solution when considering the cost of correcting the core issue(s)). So all I can offer are some bits of info and my opinions - and none of it may be useful, but I can only hope. So here's some of my ramblings.

First and foremost we should recognize that the simple little VW engines are full of amazing technical wizardry in their design (same basic motor design as Porsche - one the top sports cars then and now). In this case the excessive pressure in the crankcase as you describe can likely be traced down to one (or more) of three sources:
1. Ring blow-by.
2. Valve guide blow-by.
3. Crank end bearing wear (primarily on the pulley end).

Problems with the first two can usually be revealed by a good compression and blow-by test - an analysis of those two results can aim you at the specific problem areas (which cylinder's rings are worn, or which valve guides are suspect). The amount of oil leaking from the crank seal behind the main pulley can indicate the degree of wear on that bearing. As well, crank end play outside of factory specs indicates a potential for increased crankcase pressures. The reason for the pressure buildup from that area is that the groove cut into the crank bearing surface (the screw-like small continuous groove in the bearing surface) is there not only to sling oil through the bearing area, but to also draw air into the crankcase at the same time (remember my amazing technical wizardry comment)!

So now let's take the shade-tree method for doing a crankcase pressure test. Take a paper towel and lay it flat over the oil filler opening (remove cap first) and rubber band it taut. Now start the engine and let it idle for a few minutes (don't rev it up, and it should be warmed up before starting this test). The results on the paper towel will be a quick indicator of the level of crankcase pressure. If it has a slight buzz while the motor is running, and does not accumulate excessive oil, you are in good shape. If it becomes oil soaked and shows heavy movement with the motor cycling, or even blows out, you are at the undesirable end of the spectrum.

OK, so all my ranting probably adds nothing to your question of catch-tank or no catch-tank. To address that directly, yes I think one would serve your intended purpose wonderfully. I just always like to explore the source problem before I look for the easiest fix. Such as, if your crank endplay is out of spec (worn bearings) and oil is leaking behind the pulley, other invisible cures are available such as a 'sand seal' behind the pulley which is an additional seal that is installed from the outside and will correct both the oil leaks and the excessive crank pressure (if that is the key problem area).

Enough, cause now I'm getting myself mixed up (happens more and more as I get older). Good luck, and have fun with your toys.

All advice given carries a money-back guarantee.

 

[Loner]

By the way - I follow the same belief as Slick Rick. Aircooled VWs are not always oil gushers or drippers. But, because of their horizontal layout and the aircooled open cylinder designs, normal wear and tear often includes some of the numerous oil seal areas.

I have for about twenty years procured and used many new VW OEM motors fresh from a VW factory. Installed and run for many, many thousands of miles with no signs of leaks. And then, years later we get a slight drip from the oil change gasket (cause it is disturbed and changed with every oil change - install an aftermarket cover with oil change bolt at first oil change), then valve cover gaskets (cause they are changed with every valve adjustment), Then pushrod tube ends (cause the stretchy part of the tube relaxes with age), then rear oil seal, then front oil seal. If I stay on each leak as they happen the motor stays leak free. When I get lazy and say it's just a few drops, the war is lost.

(o\ ! /o)

 

[Doug D.]

Thanks, guys! I appreciate all the input. I'll keep pluggin' at it 'til I figure it out!

Ride safe!

 

[vw driver]

Guys I'm having to learn a lot about these engines but I have a type 3 and honestly it has no more than a drip every once in a while , uses no oil between changes . I don't know if it's just a good one or the type3 operates a little different or it being a stock engine it doesn't do it .

The Type 1 and Type 3 are the same long block. I'm putting a new main seal in our bus right now, it went out and got oil on the clutch which started slipping. You haven't lived until you've wrestled with a 40 year old gland nut.

 

[slick rick]

I new from everything I've read it was , I thought . Good luck with your project !!!!!ThumbUp