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pauciullo · 03-18-2023, 05:28 AM

Good morning guys i have an issue but don’t know if it is an engine or trans issue. I have a 1995 newmar with a 8.3 Cummins with an Allison md3060. If i am on the highway and get off the motor will still when i come to a complete stop. If it doesn’t stall it will “catch” itself. I can replicate it if i put it in gear and hold the brake hit the throttle and lay off.
I have changed the fuel filters numerous times. The previous owners did not do maintenance on the rv for a bunch of years. I would imagine they did not do the trans filters and fluid so that is on my list of things to do. Any input on what it can be ? Here is a video of it

https://youtube.com/shorts/blqc-qbBspQ?feature=share

wolfe10 · 03-18-2023, 06:07 AM

Pretty easy to check the transmission for Diagnostic Codes using your shift pad:

Ignition on, engine OFF.

Press the Allison up and down arrows at the same time. That will likely bring up OL-- (for oil level).

If it does, press the up and down arrows again at the same time. That will bring up d-1 and any stored diagnostic codes.

Earlier transmissions did not have the oil level feature, so they went directly to diagnostic codes.

If there is a diagnostic code, after recording it, press the mode button to go to d-2. Continue until you get d-"whatever" and --.

Turn off the ignition to exit.

pauciullo · 03-18-2023, 07:35 AM

Quote:

Originally Posted by wolfe10

Pretty easy to check the transmission for Diagnostic Codes using your shift pad:

Ignition on, engine OFF.

Press the Allison up and down arrows at the same time. That will likely bring up OL-- (for oil level).

If it does, press the up and down arrows again at the same time. That will bring up d-1 and any stored diagnostic codes.

Earlier transmissions did not have the oil level feature, so they went directly to diagnostic codes.

If there is a diagnostic code, after recording it, press the mode button to go to d-2. Continue until you get d-"whatever" and --.

Turn off the ignition to exit.

good morning I just got up and pulled the codes. this is what I got

https://www.youtube.com/watch?v=irOMo-jKo4k

wolfe10 · 03-18-2023, 07:37 AM

So, no diagnostic codes.

Said another way, from an electronics standpoint the transmission is happy.

pauciullo · 03-18-2023, 08:20 AM

could this be a fuel delivery issue ? its just odd that it does it only in gear.

wolfe10 · 03-18-2023, 08:23 AM

Quote:

Originally Posted by pauciullo

could this be a fuel delivery issue ? its just odd that it does it only in gear.

Yes it could. Any air in the fuel filters? Dirt or water? An indication of a problem.

Also, verify that the fuel shutoff solenoid is opening all the way.

pauciullo · 03-18-2023, 08:39 AM

Quote:

Originally Posted by wolfe10

Yes it could. Any air in the fuel filters? Dirt or water? An indication of a problem.

Also, verify that the fuel shutoff solenoid is opening all the way.

Where would the fuel shut off solenoid be ?

I did the fuel filters a few times and still had the same results. Also had no signs of dirt or water. I did a fuel treatment in it just to be sure I need to do the air filter

wolfe10 · 03-18-2023, 08:42 AM

Quote:

Originally Posted by pauciullo

Where would the fuel shut off solenoid be ?

I did the fuel filters a few times and still had the same results. Also had no signs of dirt or water. I did a fuel treatment in it just to be sure I need to do the air filter

The fuel shutoff solenoid is on your injection pump (passenger's side of engine).

What does your air filter minder read? Have you tested it to make sure it is working properly?

And, how old is the air filter. Since they are made of paper, they DO degrade with time as well as accumulated dirt.

NevadaNick · 03-18-2023, 09:22 AM

Is the engine brake stalling it ?

pauciullo · 03-18-2023, 09:33 AM

Quote:

Originally Posted by wolfe10

The fuel shutoff solenoid is on your injection pump (passenger's side of engine).

What does your air filter minder read? Have you tested it to make sure it is working properly?

And, how old is the air filter. Since they are made of paper, they DO degrade with time as well as accumulated dirt.

Air filter doesn’t have a minder on it. I need to swap in a new one.
I am just confused on why it only does it in gear

pauciullo · 03-18-2023, 09:36 AM

Quote:

Originally Posted by NevadaNick

Is the engine brake stalling it ?

No sir it’s off

wolfe10 · 03-18-2023, 09:41 AM

Quote:

Originally Posted by pauciullo

No sir it’s off

A very good question.

What brand exhaust brake do you have?

I have seen them fail to open, particularly if not maintained.

Pac Brake exhaust brakes do require lubrication:

https://pacbrake.com/product/c18037-superlube/

pauciullo · 03-18-2023, 11:43 AM

Quote:

Originally Posted by wolfe10

A very good question.

What brand exhaust brake do you have?

I have seen them fail to open, particularly if not maintained.

Pac Brake exhaust brakes do require lubrication:

https://pacbrake.com/product/c18037-superlube/

would the exhaust brake still cause the issue only while the transmission is in drive? I dont even use the exhaust brake.

Gallivant · 03-18-2023, 01:56 PM

My 2000 Monaco Windsor Cummins ISC had an in-line one way check valve just before the primary fuel filter. I’ve had algae/crud get stuck in there and more recently rubber bits that acts like bubble gum. Both of these have eventually blocked fuel delivery when the filters where good. I didn’t even know about this valve as it looks like regular fittings back there. New supply and return hoses and FASS pump have cured my issues.