Leaking turbos after overhaul

[INTERPRO]

Good afternoon,

I just did an overhaul after 1.4M miles and I noticed that the new remanufactured turbo from Cummins was leaking oil excessively thru the cold side. It was spinning at 11k RPMs and it had about 2.5lbs of PSI at 18% on the actuator position. I got a second turbo with similar results.

I decided to install the original turbo because I didn't have that problem before the overhaul. Once I tested the original turbo I noticed it also started leaking oil at a lower rate, but this one made more sense because I had 0 PSI boost at idle at 10k RPMs with 18% on the actuator position. I attached some pictures at different engine RPMs. I been running the @m*m^2 since October 2015 without any problems.

Things I checked:

Ventury pipe was welded instead of using the stainless washers
Oil drain pipe from the turbo to the engine block is clear
I am using the maintenance free crankcase breather insert.
calibrated the VGT actuator.
I don't have any restriction on the air filter.
No excessive blowby.
I dont have any engine codes
I double checked the pressures with a streeglow gauge that has a vacuum and 0-30 psi reading.

Thanks in advance for any help.

   
   
   
   

[Rawze]

The program needs an update. It should not be only set at 18% at idle.. as this alone has since been known to cause it to pull a vacuum on the face of the turbo and suck oil out of it. The turbo needs positive pressure on it at all times for it not to bleed oil. You might have gotten lucky with the turbo not bleeding oil in the past at such low idle positioning, but it cannot be relied on.

Most engines have to be set to about 48% or higher at idle to get proper positive pressure at the intake.

you also did not mention what kind of engine it is either. CM871?. CM2250?. CM2350?... you did not mention this.

It also should not have changed boost levels so radically from one turbo to the next .. unless you changed turbo models or something. Something did not add up there.

(a simple validation) ...
To check for a vacuum at the intake.. remove the IMAP sensor from its hole on the intake side of the engine without unplugging it. Crank the engine and feather the throttle a few times hard to get everything settled and running good. - Then place the corner of a sheet of paper over the hole with the engine running at idle .. and see if it mostly wants to suck the corner of the paper up into the hole or not.

If it mostly tries to get sucked into the hole .. then the turbo is not spinning fast enough at idle to keep up and has a high chance of bleeding oil.

If it mostly only flutters up and down and does not really want to get sucked in.. or blown up away .. then it is about right.

If it mostly wants to be blown up and away with some positive force from the hole .. then it is spinning a bit too fast for idle... and is costing fuel consumption at idle unnecessarily.

=================
NEXT: .. if there is any restriction whatsoever in the crank case ventilation system.. the crank case filter is dirty, clogged, etc.. then it will also cause the turbo to bleed oil out of its face (plus cause significant harm to the engine too). It being a fresh inframe.. and likely having some extra blo-by until it gets broke in good.. this may be part of the issue too.

make sure the crank case filter is 100% hollowed out or is one of the maintenance free ones.

[INTERPRO]

(03-05-2023 )Rawze Wrote:  The program needs an update. It should not be only set at 18% at idle.. as this alone has since been known to cause it to pull a vacuum on the face of the turbo and suck oil out of it. The turbo needs positive pressure on it at all times for it not to bleed oil. You might have gotten lucky with the turbo not bleeding oil in the past at such low idle positioning, but it cannot be relied on.

Most engines have to be set to about 48% or higher at idle to get proper positive pressure at the intake.

you also did not mention what kind of engine it is either. CM871?. CM2250?. CM2350?... you did not mention this.

It also should not have changed boost levels so radically from one turbo to the next .. unless you changed turbo models or something. Something did not add up there.

(a simple validation) ...
To check for a vacuum at the intake.. remove the IMAP sensor from its hole on the intake side of the engine without unplugging it. Crank the engine and feather the throttle a few times hard to get everything settled and running good. - Then place the corner of a sheet of paper over the hole with the engine running at idle .. and see if it mostly wants to suck the corner of the paper up into the hole or not.

If it mostly tries to get sucked into the hole .. then the turbo is not spinning fast enough at idle to keep up and has a high chance of bleeding oil.

If it mostly only flutters up and down and does not really want to get sucked in.. or blown up away .. then it is about right.

If it mostly wants to be blown up and away with some positive force from the hole .. then it is spinning a bit too fast for idle... and is costing fuel consumption at idle unnecessarily.

=================
NEXT: .. if there is any restriction whatsoever in the crank case ventilation system.. the crank case filter is dirty, clogged, etc.. then it will also cause the turbo to bleed oil out of its face (plus cause significant harm to the engine too). It being a fresh inframe.. and likely having some extra blo-by until it gets broke in good.. this may be part of the issue too.

make sure the crank case filter is 100% hollowed out or is one of the maintenance free ones.

[/b]
[b]

Thanks for the reply.

I have the CM871 engine @m*m^2 485hp overlay.

I did the paper test and it does have a vacuum (it constantly sucks the piece if paper). I can't remember where actuator percentage was before the overhaul.

I replaced the ECM in 2020. I backed up the original ecm and restored it into the new one. Would this change anything on the commanded actuator percentage?

I already have 8k miles on tha tractor after the overhaul. How long would I need for it to be considered broken in?

I am using a maintenance free breather insert instead of the filter.

This is the old turbo
   
This is the new turbo

[MPDiagnostics]

I would double check with Rawze on your file. It may have not copied the RAM parameters after replacing your ECM. Something Rawze and the other guys know more about.

[INTERPRO]

Hi, can someone help me by looking over my cal files to check why my actiator position is at 18% when i am idling.

Thanks

[Rawze]

(03-11-2023 )INTERPRO Wrote:  Hi, can someone help me by looking over my cal files to check why my actiator position is at 18% when i am idling.

Thanks

copy the file out of the ecm and e-mail it to me. I will review it and ensure it is ok.

And by the way.. the MM for the cm871 sets the turbo at 48% at idle last I checked ... not 18%. What you have must be seriously out of date or something, or perhaps not from its official source.

It should be version '1505W'.