Built a Catch Can - PeachParts Mercedes-Benz Forum

mach4 · #1 08-24-2012, 08:53 PM

I've got a California version OM617.952 in my 107 and since I completed the swap, I've been just dumping the raw valve cover vapor directly into the air intake just ahead of the turbo. Unlike earlier cars that have a separator that returns oil to the sump the later ones just dumped everything into the intake. Having cleaned out the intake and not wanting to do that job again, I decided to fabricate a catch can to strip out the oil from the vapors.

I've seen quite a few methods but decided to try something of my own design.

I created a mock up using cardboard to fit the space I had between the existing brackets in the engine bay. I cut and welded the box. (I was going to go use the brake but decided to use the old vice and hammer trick) Before welding on the cover, I welded in female 1/4 NPT fittings using steel air hose fittings with the barb cut off.

I filled the cavity with stainless wool to provide a good substrate for the oil to condense out on. By having the intake and exhaust on opposite ends the vapor will have to transit a good 6 inches of stainless wool that should do a pretty good job.

Here's the completed custom catch can ready to be installed.

And here is the finished product installed in the car.

My 617 has an early "smooth" pan upper oil pan, (that I needed for subframe clearance) and that has the check valve for returning oil to the sump, so I was able to just use the original oil return line for my catch can drain line. This drain line exits the bottom of the catch can at the lowest point.

I'm anxious to see how well this works, but certainly it can't be any worse that the original setup. And without the EGR my intake and turbo should be quite clean moving forward.

Diesel911 · #2 08-24-2012, 09:21 PM

Prediction; the Breather is going to out last the rest of the Car!

sixto · #3 08-24-2012, 10:40 PM

How do you drain the catch can?

Sixto
87 300D

mach4 · #4 08-24-2012, 11:20 PM

Quote:

Originally Posted by sixto

How do you drain the catch can?

It drains into the sump. I replaced the ribbed upper oil pan with the smooth earlier one that has the drain fitting.

I used a small section of the original drain tube and connected a 5/16 hose barb to it to and connected that to a fitting on the bottom of the catch can. If I didn't have that, I would have either drilled and tapped the pan for a fitting or tied into the turbo drain.

charmalu · #5 08-24-2012, 11:24 PM

Quote:

Originally Posted by sixto

How do you drain the catch can?

Sixto
87 300D

He mentioned it here in this sentence:

My 617 has an early "smooth" pan upper oil pan, (that I needed for subframe clearance) and that has the check valve for returning oil to the sump, so I was able to just use the original oil return line for my catch can drain line. This drain line exits the bottom of the catch can at the lowest point.

Acftually the intake won`t get gunked up as long as the EGR isn`t dumping soot into the mix.

I have pulled several manifolds from the w126 78 and 79 pre EGR, and they are just oily inside. no gunk.

Your catch can almost looks like it belongs there. nice job.

Charlie

sixto · #6 08-24-2012, 11:39 PM

Doh! I didn't read that far.

How about a temporary section of clear hose to the turbo inlet to see how clean (or not) the charge is?

Sixto
87 300D

mach4 · #7 08-25-2012, 12:37 AM

Quote:

Originally Posted by sixto

Doh! I didn't read that far.

How about a temporary section of clear hose to the turbo inlet to see how clean (or not) the charge is?

I'm running clear hose to the drain right now to monitor that. I've got a proxy for the turbo inlet, in that my connector between the turbo and intake manifold has a small air leak. It was producing an oil slick down the intake manifold, which is how I knew I was getting oil into the intake. It's not excessive in that I'm down about a quart over 3000 miles including leaks, valve cover vapor condensate and whatever gets by the rings/valves/turbo seal.

mach4 · #8 08-25-2012, 12:45 AM

Quote:

Originally Posted by charmalu

Your catch can almost looks like it belongs there. nice job.

That was one of the design criteria and the major reason I didn't go with one of the kits... plus they don't normally have a drain.

DeliveryValve · #9 08-25-2012, 04:49 AM

As usual, nice work. Like Charlie stated, it looks almost factory. I may have to copy that idea....

.

kerry · #10 08-25-2012, 12:09 PM

Nice work. A soda bottle would work though

The earliest turbos in the 116's just fed the PCV line directly to the u-tube leading to the turbo.

mach4 · #11 08-25-2012, 01:17 PM

Quote:

Originally Posted by kerry

Nice work. A soda bottle would work though

The earliest turbos in the 116's just fed the PCV line directly to the u-tube leading to the turbo.

You're absolutely right. Almost any container filled with steel wool would work.

I actually spent quite a bit of time at the junk yard looking for something that could be modified to do the job. One of the more interesting things i found was an A/C dryer from a BMW. It was a great shape, the right size and already had two ports on the top for the intake and exhaust, and a tapered bottom for a nice drain, but no mounting bracket. Unfortunately it was aluminum and tough for me to weld. So I just designed my own around the space and existing brackets I had available.

LoosBenz · #12 08-25-2012, 08:46 PM

Years from now, someone will be swearing that there is a Mercedes part number for that : )

Graham · #13 08-25-2012, 09:15 PM

Quote:

Originally Posted by mach4

You're absolutely right. Almost any container filled with steel wool would work.

On my 85 300D, I had an 82 SDL engine (I think) installed that does not have a place to return oil to sump. But I have the 85 air cleaner. What I did, is plug the drain off the air cleaner center catch tank and install an access plug in the top. I just suck the oil out of the catch tank each time I do an oil change. Some oil no doubt get sucked into the intake, which is the way the old cars were, I believe.

A number of cars use a small cyclone.

This one is off a BMW:

GENUINE BMW Oil Separator Crankcase Ventilation System Cylinders 1-4 Right Part #11 15 1 406 788

this is a home made one:

and this one off a Landrover

mach4 · #14 08-25-2012, 11:23 PM

Quote:

Originally Posted by Graham

On my 85 300D, I had an 82 SDL engine (I think) installed that does not have a place to return oil to sump. But I have the 85 air cleaner. What I did, is plug the drain off the air cleaner center catch tank and install an access plug in the top. I just suck the oil out of the catch tank each time I do an oil change.

I like your examples.

Most of the commercial catch cans come with a sight gauge and are designed to be manually drained.

Since I had the drain in the oil pan from the earlier version 617 I decided to just make it totally automatic. I might have opted for your solution but I don't have room for any stock air cleaner. Right now I'm using a gauze/oil air cleaner solution on a temporary basis, until I get my paper filter setup mounted. As you can see, I'm kind of tight on room.

The problem with the paper filter setup is that there is almost no where to tie in a fitting for the "clean vapor". I might just go with a small filter and vent to air.

Graham · #15 08-25-2012, 11:56 PM

Quote:

Originally Posted by mach4

As you can see, I'm kind of tight on room.

The discussion the cyclones came from was a Canadian diesel smart car forum. Even more tight for space!

But stock air filter is used. (lower duct in pic). The oil is drained via a tee in the dipstick tube.
On the Beemers, they use two cyclones. One for each side, presumably V6.

Good luck with the project - looks good!