Has Anyone Used an Electric Pump to Suck out Blow-by and Decrease Oil Leaks?

[Diesel911]

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?

[oldsinner111]

looks like any small 12 volt vacumm would do the job

[kerry]

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

[Diesel911]

Originally Posted by kerry

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

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

[Diesel911]

Originally Posted by oldsinner111

looks like any small 12 volt vacumm would do the job

That would work until the Oil Vapor ruins the Electrics.

Also a Vacuum Cleaner is not made for continuous use.

[Diesel911]

Some other comments:
Automotive Crankcase Ventilation Systems Diagram PCV

[Stretch]

Originally Posted by Diesel911

...

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.

...

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?

[kerry]

Originally Posted by Diesel911

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

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.

[Admiral Ahani]

Also interested in a passive solution.

[kerry]

All you really need to do is run the PCV line into an oil separator and vent the other side to atmosphere and you're good to go. Forced Induction used to have a picture of his system on here in the past. Long gone now I think.

[Dubyagee]

Dragsters use a scavenger system and venturi tube in the exhaust to draw out combustion gases and maintain a small amount of vacuum in the crankcase to prevent oil leaks on to the race track.

You could run a line from the valve cover to the intake.

[kerry]

Originally Posted by Dubyagee

You could run a line from the valve cover to the intake.

ie, the PCV system.

[Diesel911]

Originally Posted by Army

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?

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.

[Diesel911]

Originally Posted by kerry

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.

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.

[Diesel911]

Originally Posted by Dubyagee

Dragsters use a scavenger system and venturi tube in the exhaust to draw out combustion gases and maintain a small amount of vacuum in the crankcase to prevent oil leaks on to the race track.

You could run a line from the valve cover to the intake.

The older Mercedes Diesels have Intake Manifold Vacuum but the newer ones do not.

On the Turbo Models you cannot connect it to the Intake Manifold because the Boost Pressure will go into the Crankcase.