W108 Crankcase breather filter? - PeachParts Mercedes-Benz Forum

n10 · #1 01-11-2015, 12:46 AM

Since I swapped out Zenith carbs for Webers I was not able to retain the stock circular airbox. The JAM supplied towers were too tall and left a gap.

I have a set of DGEV filters for that but...

Since the recycled air emissions has been cut off I can no longer use the breather hose to divert nasty blowback from the crankcase back in the engine. Currently I have nothing connected to where the breather hose connected to the crankcase

Is there a way to connect a charcoal filter or something to cut down on the nasty blow by gasses? Driving is no problem but at a stop light I get stink going in the cabin.

mosu · #2 01-11-2015, 01:10 AM

Did you look into one of those Weber lunch box type filters with a breather hose fitting in the bottom layer?

This one for example:
1 3/4'' DFV AIR FILTER
99217.474G

n10 · #3 01-12-2015, 09:46 AM

That's actually what I ended up with. Not sure if I should reroute the dirty air back in that though.

mosu · #4 01-12-2015, 10:41 AM

Sorry, I should've read your post closer. You're saying that there's no room to run a hose between the intake manifold breather connection and the valve cover fume output nipple?

If that's the case, I don't see anything wrong with your current setup. I've used it on other cars. One of the carbs will have to be tuned to account for the blowby (I think leaner).

n10 · #5 01-12-2015, 11:10 AM

Close..

I blocked off all return lines back into the manifold. I think if I rerouted back to one of the carbs that thing would foul and get really dirty pretty quick.
That recycled air is nasty so Id rather plant another tree instead of ruining a carb

Maybe something like this...

mosu · #6 01-12-2015, 01:46 PM

I think the system relies on a small amount of vacuum to operate correctly. The fitting in the manifold is restricted and only pulls about 8 in Hg at idle (or mine it plugged

). I think you're ok dem nasty fumes thru the carb.

n10 · #7 01-17-2015, 05:45 PM

Update...

So I found the perfect lil filter from K&N...62-1360 - K&N Crankcase Vent Filters, Vent Air Filter

It fits directly on the crankcase and works like a charm. I assume it will get dirty pretty quick but at least its cleanable. FYI its cheaper on Amazon

n10 · #8 04-03-2015, 12:32 PM

Another update just for kicks...

So the filter didn't hold up as long as intended. My rings are worn and blowby was fouling the filter quicker than I liked. Until either a swap or rebuild happens I came up with another crude solution.
Currently I have a 20mm hi temp vacuum hose connected to the breather vent and routed it down to under the car just under the driver seat. No more fumes in the cab! There is plenty of room when the hood is closed so the hose doesn't get pinched under there

Idle · #9 04-03-2015, 03:07 PM

I was going to suggest the hose or pipe out the bottom or back.

Late 40's, early 50's, GM cars and trucks had a down pipe which I think they called a blow by pipe. It just fit on top of the valve cover and ran down the side of the engine. Since engine didn't last much past 60,000 miles back then and oil was cheap it was not unusual to see one of these trucks sitting at a light with smoke just belching out from under it.

Do you have room to put in a plate under the carb with a port on it to direct the hose to? That way the vac of the engine would pull the fumes through and perhaps burn them some more and it would not foul your carb. It would be rough on your spark plugs, though, since it was on GM engines when they went to this set-up.

But there is a fix for that, too! Do some Google work on the term 'anti-foulers for sparkplugs' and you will learn how that solution to plug fouling works.

It's crude, but effective.

n10 · #10 04-03-2015, 03:56 PM

Learning something new everyday!

I had no idea that these anti-foulers existed

Well that being the case, if you look closely at my last pic...There is a little yellow/white dot inbetween the carbs. That is a plug that goes directly into the manifold after the carbs. I plugged it up from the original carb set up.
I suppose if I could dump that 20mm hose down to whatever size inlet that is, (possibly 8-10mm) I could pull that off.
Then toss some anti-foulers on and see what happens...

mytmousemalibu · #11 04-03-2015, 04:11 PM

If you look up oil separators, there are a number of good options. I actually built my own from PVC and a few fittings for cheap and worked very well.