The old Blow-by issue is making the rounds on the Various Forums again.

On one a Member said He used a Electric AC Delco 215-425 New Air Pump, GM 12568324 $130-150 range to suck out the Blow-by.

Hunter also recently posted a thread on the cost and labor involved in changing the Rear Crank Seal.

I have read that similar Pumps can be to decrease the amount of Oil leaking from the Seals because the decrease or eliminate Crankcase Pressure.

My question is has anyone had experience with such devices and the results in reducing Oil Leaks?

__________________
84 300D, 82 Volvo 244Gl Diesel

looks like any small 12 volt vacumm would do the job

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

That would work until the Oil Vapor ruins the Electrics.

Also a Vacuum Cleaner is not made for continuous use.

__________________
84 300D, 82 Volvo 244Gl Diesel

Pumping air into the crankcase with the engine vacuum pump and pumping it out with another vacuum pump?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

No, it is a Vacuum Pump that you would hook to the Crankcase Breather Tubing to evacuate the Blow-by and reduce or eliminate the Crankcase Pressure.

I did not mention it but there is a few commercial purposely built Pumps to do the above but they are expensive.

I just wanted to see if any one has tried something similar and if it decreased any Crankshaft Seal leaks (the commercial ones say it reduces or eliminates leaks).

This is not an Electric Vacuum Pump but it explains the idea some:
LSX Series (LS1-LS2-LS7) Vacuum Pump Kits for Corvettes, F-Body & GTO

__________________
84 300D, 82 Volvo 244Gl Diesel

My point was that the engine vacuum vents into the crankcase hence pressurizing it. If there is a way to stop the existing vacuum pump from venting into the crankcase, you could avoid a second vacuum pump. I would think venting the crankcase to atmosphere would be entirely adequate since pressure could never build up.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

On the Piston Type Vacuum Pumps there is no way to vent outward because of where the Valve for that is located by the Vacuum Pump Arm.
The Blow-by is vented to the Atmosphere but it goes through the Hole in the Valve Cover.

Someone could come up with a vent the fits and replaces the Oil Fill Cap. But, the same ID Tubing/Hose needs from there to somewhere.
If it goes to the Air Filter Housing it is going to take some mods.

If it goes to the Ground you should have some sort of Filter on the end of it.

Concerning decreasing Oil leaks having a Vacuum in the Crankcase should be more beneficial than having no Crankcase pressure.

__________________
84 300D, 82 Volvo 244Gl Diesel

That's what I mean by an oil separator. Run the line into a jug and another line out of the jug. There'll be a vent to atmosphere and the oil can drop into the jug.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Some other comments:
Automotive Crankcase Ventilation Systems Diagram PCV

__________________
84 300D, 82 Volvo 244Gl Diesel

Do you happen to know how much pressure is produced in a crankcase on a new (unworn) engine?

On a worn engine I guess it can shoot up quite a bit!

Could this pressure be reduced in a passive way - such as via a gauze filter - instead of the active solution you suggest?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

If the Hole in the Valve Cover was big enough you could reduce the Crankcase pressure. The restriction is the Valve Cover Hole.
(My Father had Dodge that had a 6 Cylinder inline Engine. It had badly worn Exhaust Valve Guides and the exhaust gasses increased the crankcase pressure to the extent Oil would come out from between the Oil Pan Gasket and the Block. If you drove without the Oil Fill/Breather Cap the Oil did not come out but you needed to keep all the Windows rolled down and it would still bring tears to your Eyes to drive the Car. The Car otherwise drove well and got good Milage.)

That would help keep Oil from getting pushed out of the Seals but would not suck it back into the Crankcase.

I have no idea what is a normal Crankcase Pressure for a new Engine.
I have Blow-by and I don't know how much pressure is there either. I know if I occlude the Rubber Elbow on the Valve cover with my Thumb with in about 7 seconds the Engine starts to bog down.

From what I have read the Crankcase Pressure pushes the Vacuum Shut off into the shutoff direction.

Hunter posted a thread several days ago and the short story is the Engine needs to come out to replace the Rear Main Seal. To have a Shop do the Job is expensive to the extent that He believed Shops inflated the price because the did not want to do it.

I was just curious to know if installing a Vacuum Pump to decrease the Crankcase Pressure might decrease or stop such a leak for those who can't pay for or DIY the Rear Seal Replacement.

__________________
84 300D, 82 Volvo 244Gl Diesel

Holy crap!

7 seconds to bog down...

Hmmm I'll give it some thought.

As for the crankcase pressure effecting the vacuum pump.

Assuming you've got a piston pump => I can imagine that it would be harder for the pump to push against the crankcase pressure. If the non return valve in the vacuum pump was leaking then I can imagine that the piston assembly would be pushed back towards the engine so that the bearing race is always in contact with the bearing track on the front of the timing device. I think the crankcase pressure would reinforce the spring pressure in the piston vacuum pump.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

The shuttoff issue does not have to do with the Vacuum Pump.
It has to do with the fact that the Fuel Injection Pumps Camshaft and Governor Housing are connected to the Crankcase and exposed to the Crankcase Pressure.
One side of the Vacuum Shutoff Diaphragm is esposed to the Crankcase Pressure that is in the Fuel Injection Pump Governor Housing.
If the pressure inside of the Housing rises enough it pushes the Diaphragm the same direction Vacuum would pull it if you applied Vacuum to it and can shutdown the Engine.

__________________
84 300D, 82 Volvo 244Gl Diesel

Oh right - sorry I misunderstood what you meant.

Very interesting problem for the Mercedes Myth Busters here. I like it! The more we talk about these cars the better we get to understand them - we get to a stage where we think we've seen it all before and wham bam! here comes another little idiosyncrasy.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I've been reading though the FSM trying to find out more about the return flow of oil from the IP.

Chapter 18-005 in both the turbo and non-turbo FSM versions don't help much. The only mention I can find about the return is in chapter 7-010 showing the "new" oil fed injection pumps...

...Oil goes in via the intermediate shaft and returns "to the crankcase" - how it gets there and the path it takes isn't clear in the FSM. I'm going to have to take my engine to bits again to see!


Even so for the crank case pressure to effect the diaphragm at the end of the IP the crank case pressure would have to be greater than the oil pump pressure...

...wouldn't that cause lots of other lubrication problems within the engine? Jets on the turbo OM617 version would have trouble spraying oil up and into the bottom of the cylinders for example.

Now I don't know by how much the oil pump pressure gets reduced by the time it reaches the IP (and crawls its way though the small path way through the intermediate shaft) - I guess that needs to be measured - but how?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!