Oil Bath Air Filter Filling with Oil

[Cairo1966_W110]

I have an OM615 engine fitted in my 1966 W110 (not the original engine....). 4 cylinder diesel engine from around 1976 I would guess.

Recently, after emptying and cleaning the oil bath air filter, I added oil to the correct level. After a few weeks, I have checked it again and the oil is at least double the level I filled it to. Engine oil level has gone down as well, I've topped it off thinking some of it was getting burned. But around 500 ml added for roughly 800 km, just to keep the dip stick mark in the middle of the range.

Any ideas why the oil level is increasing in the filter bath? Does it mean blow by and oil is coming up out of the valves? There is a tube from the valve cover cap to the oil bath.

I have purple smoke on start up, goes away after 5 min or less. Then no smoke except some faint black smoke when accelerating up an incline. No lack of power or any other symptoms.

Could it be just too much oil in the engine, ends up in the oil bath?

[Sugar Bear]

It could be too much oil in the crankcase and/or piston ring blowby. Be certain not to overfill the crankcase. Also, search on oil "catch can", you may need to add one to the breather hose.

If it is blowby that can be caused by stuck or dirty piston rings, before condemning the engine do a piston ring chemical soak.

Good luck!!!

[Diesel911]

On gasoline engines I have seen Oil get by worn valve guides and stems. But on them they usually used simple deflectors not valve stem seals as they were not overhead cam engines.

In your case I would be thinking work valve stems or guides and the Valve Stem Seals.

Note I also drove a gasoline engine car that had worn exhaust valve stems and or guides where if you left the breather cap on the crankcase pressure built up high enough to cause Oil to come out of the Oil Pan to block gasket area. Driving with out the breather on solved the problem (that was the one on the valve cover). (Note this was in the very early smog emission days.)

[Idle]

I have seen a lot of 240d cars from the 123 series with oil all over the top of the engine. I once asked a mechanic about this and he said it was from a worn timing chain. It somehow got everything a little out of whack and created a lot of pressure in the crankcase which resulted in the oil blowing out of somewhere. And that somewhere was usually the oil flller cap.

The car seemed to run fine.

I think these oil catch cans spoken of earlier were common on the 111 and 110 with power brakes. Since they took their vacuum right off the crankcase part of the engine it was just a matter of time before they started sucking oil in a vapor form into the brake booster. There the oil would cause the diaphragm in the booster to break down. But with the inline catch can you could see oil collecting in the translucent can before it caused any damage to the booster.

Search Ebay or a wrecking yard for one of these inline brake booster oil traps. I don't think they are that expensive and with one inline between your crankcase hose and the air filter you would be able to see if this is where your excess oil is coming from.

[Cairo1966_W110]

Thanks everyone for their replies. Some more info....

It could very well be that there is excessive blow by and this is venting oil into the crankcase. The rest of the engine is clean, and there are no oil leaks or drips. She burns very little oil...

The set up of the hoses coming from the crankcase is different than what I have seen on other cars. Photo is attached. There is a tube directly from the oil filler cap to the oil bath air filter - this is I think where the oil is coming from. The oil breather system is in place on the, but it seems to be not connected - it goes to a T piece and then one end of that T piece is open.

My guess is this open part of the T piece should connect to the bottom of the oil bath air filter.

So, maybe a former owner set this up so at least if pressure is building in the crank case it escapes down that extra tube directly to air bath oil reservoir and not out the crankcase or another place.

So, maybe I should leave it like it is, and just clean out my oil bath air filter on a more frequent basis, which also can't hurt the car.

PS. This is an OM615 engine in my W110 ;-).....

[KCM]

The hose connected to the filler cap is why your air cleaner if filling up with engine oil, especially if there is no baffle in the cap. The oil is being sucked into the oil bath. The hose coming out of the center of the valve cover should be connected directly to the port in the side of the oil bath with no "T". If you were to take the valve cover off, you would see a baffle connected to the port that prevents oil from being sucked up into the air cleaner. The cap should be a cap and nothing else. I had the same thing happen when the baffle became disconnected from the breather fitting and kept filling up the oil bath.

[gmog220d]

Looking a that photo of your setup I noticed that you are missing a tube/hose from the rubber fitting that's down between the intake and valve cover. That rubber fitting mounts on top of a metal piece that threads into and is open to the intake runner beneath it. There is also a steel line running from there to the intake runner up front. I think this is where oil that gets past the baffle inside the valve cover is caught and allowed into the intake stream to be burned up, while the lighter gasses are routed to the intake through the missing tube/hose.




The missing tube/hose should run to the intake rubber boot right before the throttle body. Here's how the setup should look:






With that tube/hose missing the system is open and is sucking unfiltered air into the engine. It is also allowing a vacuum leak that is probably throwing off the IP's governor system, causing a bit of overfueling.

[gmog220d]

Here's a better photo of what's happening in the space between the intake and valve cover:




I recently took this system apart and cleaned up all the parts. The holes for the oil to drain through to the intake are small, and were clogged and not allowing the oil through. It was a mess. So far everything is staying nice and clean.

[Cairo1966_W110]

Wow, this is amazing, thank you so much gmog220d. This is exactly what I need is clear photos to be able to get new parts or build it myself.

I will now attempt to rebuild/clean as your photos show, and also hopefully get some better fuel economy.

Thanks again. I am away from my car for a few weeks, but once I return I will update here the progress....

[gmog220d]

Originally Posted by Cairo1966_W110

Wow, this is amazing, thank you so much gmog220d. This is exactly what I need is clear photos to be able to get new parts or build it myself.

You are welcome! Glad I could help out.

Considering that your engine is not original to the car, and that you might not have the factory rubber boot that attaches to the throttle body which you could run a hose to, I figure you could run that line to the oil bath filter instead. Apparently you already have a fitting on the oil bath housing you can attach a hose to. So long as the oil is separated out right there at the engine it shouldn't matter where the lighter gasses go in, be it at the throttle body or more upstream at the oil bath housing.

Good luck! Looking forward to seeing what you come up with.

[Cairo1966_W110]

You are correct! I do not have the original factory rubber boot which attaches to the throttle body, I have just a straight piece of rubber hose (which actually I found and fitted as the previous hose was disintegrating).

I was thinking to take the tube out of the oil filler cap, cut it a bit shorter, and fit it into the empty hole on the T piece which you put a red circle. To do that, all I need is a new oil filler cap. That will be almost back how it should be, I think.

However, I am concerned then of what others have said about extra pressure building up inside the engine and causing oil leaks. So, I have made enquiry to order the boot, let's see if I can get one. As well as some of the other rubber pieces which are cracked. I will also take the system apart and clean it very well. Maybe the "baffle" or pipe inside the crankcase is also very dirty. I think it is worth opening the crank case to see, and I have the new seal for the crankcase to the engine block as well.

Thanks again gmog220d and everyone for your answers, I will let you know how I get on!!

[gmog220d]

Originally Posted by Cairo1966_W110

I was thinking to take the tube out of the oil filler cap, cut it a bit shorter, and fit it into the empty hole on the T piece which you put a red circle. To do that, all I need is a new oil filler cap. That will be almost back how it should be, I think.

That sounds good. I think once you install a regular oil filler cap and pull the fumes from the correct port on top of the valve cover you will be fine. Most of the oil in the fumes will be separated out by the baffle inside the valve cover as it should be. Any remaining oil in the fumes will get caught and diverted into the intake by the parts on top of the intake runners in that space by the valve cover. The remaining gasses will be routed to the air filter housing and sucked into the intake to be burned up. With the system cleaned up and configured correctly you should not have any problems with pressure in the crank case unless the engine is worn out and creating more blowby than the system can handle.

To others reading this, please check me if I'm not seeing this right.

[Cairo1966_W110]

It has been a while, but the missing tube finally arrived and I have installed the system as close to original as I can, so I thought I would update. Obviously, with the system back, the oil filed air filter is no longer filling up with oil. The oil level I add to the engine stays constant (before it was diminishing as it ended up in the air filter oil bath) as does the oil level in oil bath air filter.

I don't notice any performance change. I think this was due to the fact that the correct breather hose was installed so deeply into the T piece on the air inlet, that is was blocking the other entrance.

I try to show that in photo 1.

Photo 2 is the system as I built it now. A is the connection at the top of the crankcase, B is the T piece which sits on the air inlet and C is the line which goes to the dirty side of the air filter.

Photo 3 & 4 is the system installed.

I have capped the extra tubing connection which was in the oil filler cap on the crankcase.

The only way I see that it is not original now, is that the connection from the T piece should actually go to the clean side of the inlet air. It should be connected right next to the throttle control on the air inlet. Instead, it is routed back to the bottom of the oil bath air filter housing, on the dirty side, but considerably above the oil level. I believe the suction of the engine pulls air through this tube in the direction out of the crank case. At first I was concerned I was hooking it up so that non-filtered air could get into the crankcase, but the suction is so great in the opposite direction that this never happens. Anyone please give their opinion here and correct me if it seems wrong.

I've been on several 1.5 hour drives, and all seems well. No oil consumption, no smoke, just a tiny bit at start up, same power and performance. My oil pressure gauge is pegged at 3 bar during driving, at idle and in neutral (stopped at a red light) it settles down to just below 2 bar. So, I believe I have everything working as intended, if not actually 100% correct..

Thanks to everyone above who gave advice and tips!

[gmog220d]

[Tomguy]

Awesome followup and success! Nice to see your engine is healthy after all.