Excessive Crankcase Pressure? - PeachParts Mercedes-Benz Forum

Adriel · #1 02-24-2015, 11:57 PM

Do you see what is wrong? This really concerns me!

If you don't see, it is the high crankcase pressure/blow by, evidenced by the oil pushed out the new seal, new breather elbow, and pushing up the dip stick. Could the failing turbocharger cause this?

Or, is it something else?

Oh, and this is within the last few days, when the turbocharger started making rattling noises.

Thank y'all in advance for alleviating unfounded concern!

Diesel911 · #2 02-25-2015, 12:25 AM

If the crankcase pressure gets high enough and it cannot vent off and you do not blow out a seal it will shut you down by pushing the Vacuum Shutoff Valve Diaphragm towards the shut off direction.

Worn cylinders, Piston Rings, Sticking Piston Rings, worn exhaust Valve Stems and or Guides and a leaking Headgasket are some of the things that can cause high Crankcase pressure.

I suppose really bad Fuel Injection Pump Timing and or Valve Timing due to a stretched Timing Chain can also cause it.

I am not sure if not having the Valves Adjusted would cause it. But, if you do it yourself that would cost nothing.

There is several threads on putting something in the Cylinders and allowing it to soak in hopes of freeing up the Piston Rings.

If the Rings are stuck due to some alternative Fuel I am not sure what would free them up.

Diesel911 · #3 02-25-2015, 12:28 AM

I am not sure if this is possible or not but if you have a Turbo and the Exhaust side seal is shot it may be exhaust gasses can come in through the turbo. But, I think that is a long shot.

Along with worn Valve Guides and Valve Stems I forgot the Valve Seals.

A symptomatic fix might be to put another Hole in the Valve Cover and make another Vent setup or on gassers I have seen the crankcase vent elbow built into the Oil Fill Cap. If you could ad one of those you would have more vent area.

cho · #4 02-25-2015, 02:36 AM

Quote:

Originally Posted by Adriel

Oh, and this is within the last few days, when the turbocharger started making rattling noises.

I would take care of this one first...inspect turbo shaft for play...if significant
your engine might swallow turbo in seconds...

.

Adriel · #5 02-25-2015, 02:43 PM

Quote:

Originally Posted by Diesel911

If the crankcase pressure gets high enough and it cannot vent off and you do not blow out a seal it will shut you down by pushing the Vacuum Shutoff Valve Diaphragm towards the shut off direction.

Worn cylinders, Piston Rings, Sticking Piston Rings, worn exhaust Valve Stems and or Guides and a leaking Headgasket are some of the things that can cause high Crankcase pressure.

I suppose really bad Fuel Injection Pump Timing and or Valve Timing due to a stretched Timing Chain can also cause it.

I am not sure if not having the Valves Adjusted would cause it. But, if you do it yourself that would cost nothing.

There is several threads on putting something in the Cylinders and allowing it to soak in hopes of freeing up the Piston Rings.

If the Rings are stuck due to some alternative Fuel I am not sure what would free them up.

Quote:

Originally Posted by Diesel911

I am not sure if this is possible or not but if you have a Turbo and the Exhaust side seal is shot it may be exhaust gasses can come in through the turbo. But, I think that is a long shot.

Along with worn Valve Guides and Valve Stems I forgot the Valve Seals.

A symptomatic fix might be to put another Hole in the Valve Cover and make another Vent setup or on gassers I have seen the crankcase vent elbow built into the Oil Fill Cap. If you could ad one of those you would have more vent area.

Diesel911, thank you so very much for the help!

Well, using the stop lever doesn't work, so hope don't have to test that!

Just 20,000 miles ago compression was around 340p.s.i. all around.

And, about that time a new timing chain and pump timing.

I do have coolant going somewhere, but both the P.O. and I can't find where. Nothing that would suggest blown head gasket via coolant side.

Never used alternative fuel, except B20 from the pump a couple times.

Well, does burn a lot of oil! 68.2/10 I.I.R.C.; know it was 68 something, so almost seven times the legal limit.

Interesting, but hope don't need to go there.

Quote:

Originally Posted by cho

I would take care of this one first...inspect turbo shaft for play...if significant
your engine might swallow turbo in seconds...

.

Cho, thank you so very much for the reply!

Last I checked, not a huge amount, but more than I expect from a tightly machined part. I am part way though now of turbocharger R and R. Engine somewhat cleaned (coin operated wash no longer doing so) and oil drained including the oil cooler. Stopped for lunch and to see if I could find my C.D. F.S.M..

BillGrissom · #6 02-25-2015, 02:48 PM

Do a few simple tests first to judge "blow by". Could be your engine is fine and the PCV is plugged. Unlikely, but why jump to conclusions.

With oil fill cap on, remove PCV tube and see how much it puffs out (catch oil w/ rag). If not much, the engine is fine. Even a new engine will have a slight puffing from that small hole. Then test oil fill opening. Try "cap jiggle" test, or puffing w/ hole open. Videos on youtube to judge.

Adriel · #7 02-25-2015, 03:13 PM

Quote:

Originally Posted by BillGrissom

Do a few simple tests first to judge "blow by". Could be your engine is fine and the PCV is plugged. Unlikely, but why jump to conclusions.

With oil fill cap on, remove PCV tube and see how much it puffs out (catch oil w/ rag). If not much, the engine is fine. Even a new engine will have a slight puffing from that small hole. Then test oil fill opening. Try "cap jiggle" test, or puffing w/ hole open. Videos on youtube to judge.

Mr. Grissom, thank you so much for the reply!

I will do that when have oil in.

Diesel911 · #8 02-25-2015, 09:56 PM

Assuming the O-ring on the Dip Stick is the correct one and there is no other issue with the Dip Stick the Dip Stick should not be popping out.

I have blow-by and My Dip Stick stays in place.