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JMBT · 02-25-2021, **(Subject: Turbo testing... )**

Hello all, I am looking for ideas on how to test my turbo to determine if it is pushing boost pressure into the crankcase. On or off the truck would be ok.

Any help will be appreciated! Thanks

Rawze · 02-25-2021, **(Subject: Turbo testing... )**

buy a spare drain line and put it into a bucket.

tree98 · 02-25-2021, **(Subject: Turbo testing... )**

(02-25-2021 )JMBT Wrote: Hello all, I am looking for ideas on how to test my turbo to determine if it is pushing boost pressure into the crankcase.

Just curious what symptoms are making you think this could be happening?

JMBT · 02-25-2021, **(Subject: Turbo testing... )**

Rawze: spare drain tube into a bucket,...then block off turbo and fill with compressed air through temp sensor hole? I this situation should there be NO air escaping from the oil drain? Or some just not a lot?

Tree98: I had both sides of the turbo piping off the other day and found a bit of oil in each side. I have heard this can be caused by high crankcase pressure. (Also at the same time I am gearing up to pull the transmission to fix a leaking flywheel housing gasket.) and I just noticed a small leak around the gear cover up front as well. Just don’t want to fix all the leaks until I know there isn’t an underlying problem.

Rawze · 02-25-2021, **(Subject: Turbo testing... )**

(02-25-2021 )JMBT Wrote: .. should there be NO air escaping from the oil drain? Or some just not a lot?
...

turbo seals are like piston rings ... they re not a perfect seal ... hence why any crank case pressure causes turbo slobber.

If the turbo was leaking badly enough to overcome the crank case breather system, then you would know it. The seals in the turbo would have to be pretty much completely missing at that point... and the intake and exhaust piping would be flooded with oil.

you need to look at the crank case breather system to ensure there are no restrictions.

JMBT · 02-25-2021, **(Subject: Turbo testing... )**

Thank you Rawze. So I have completely removed the crankcase breather system to check it and make sure it is open. I blew compressed air through the drain at the bottom of the breather case an all the breather hoses to make sure they are open. I am running the maintenance free insert and it has also been drilled at the top and I blew compressed air through it after I reassembled it to make sure the spring mechanism was working properly, and it is.

I know a bad air compressor can add pressure to the coolant system. Is there any chance it could add pressure to the crankcase as well?

Thanks

Signature620 · 02-25-2021, **(Subject: Turbo testing... )**

The compressor can absolutely contribute to crankcase pressure. It has a piston in it with rings like the cylinders.

marek4792 · 02-25-2021, **(Subject: Turbo testing... )**

(02-25-2021 )Signature620 Wrote: The compressor can absolutely contribute to crankcase pressure. It has a piston in it with rings like the cylinders.

Rawze and I actually discovered this on his driveway once testing for a boost leak on a CM870 was leaking air pressure right into the crankcase.

Rawze · 02-25-2021, **(Subject: Turbo testing... )**

(02-25-2021 )marek4792 Wrote:
(02-25-2021 )Signature620 Wrote: The compressor can absolutely contribute to crankcase pressure. It has a piston in it with rings like the cylinders.
Rawze and I actually discovered this on his driveway once testing for a boost leak on a CM870 was leaking air pressure right into the crankcase.

yup. we pressurized the whole enigne up to about 30 psi (both sides of turbo plated off) and found it that way.