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OD not working, M41.

Tfrasca

Tfrasca

Active member
Joined
Apr 20, 2015
Location
Ben Lomond, CA
When I pulled my M41 to fix some seal leaks, I forgot to engage and disengage the OD before removing it to release the tension from output shaft to OD.

So, to take it apart, I had to split the OD case. At that time, I pulled out the filter, solenoid, and pump housing to check on things. The o-rings all looked fine, so I carefully put it back together.

Now I have no OD. I can here the solenoid clicking under the car when parked, so I know it's not electrical. I also drive it a bit, then topped off the fluid, so it should be full enough.

Any ideas on where to start the diagnosis?
 
Just because the solenoid clicks doesn't mean it is working. the plunger should move back and forth when energized. If this is working Then oil leaking by the seals that you did not replace can cause no overdrive. Whenever it is taken apart it is very important to replace the o ring seals. They can't be counted on to work again. There are also seals on the pistons that should be replaced as well. An important check is to get the hydraulic gauge so you can measure the pressure when engaged.

Basically if the electrical part is good then the hydraulics should be tested. There used to be a member here who sold parts and testing gauges for this. I think his user name was odguru.
 
Check for a broken spring in the unloader valve or shrunken piston o-rings?
Verify that the solenoid makes a deep clunk sound and the piston/plunger moves and changes the airflow path if you air check it?
Use your rubber tip air gun on the pressure test port by the solenoid and energize it and see if pressure builds up and dead heads vs. hearing continual hiss when de-energized? (primitive test)
(hard to tell as some slight leakage to lube the pump cam through the hollow main shaft is norma even with the solenoid energizedl).

Got a pressure gauge that goes up to 700psi to run it on the lift/jack stands and see if it is making 500+psi to engage?

Would this be D-type or J-type?
 
Kjets On a Plane said:
Check for a broken spring in the unloader valve or shrunken piston o-rings?
Verify that the solenoid makes a deep clunk sound and the piston/plunger moves and changes the airflow path if you air check it?
Use your rubber tip air gun on the pressure test port by the solenoid and energize it and see if pressure builds up and dead heads vs. hearing continual hiss when de-energized? (primitive test)
(hard to tell as some slight leakage to lube the pump cam through the hollow main shaft is norma even with the solenoid energizedl).

Got a pressure gauge that goes up to 700psi to run it on the lift/jack stands and see if it is making 500+psi to engage?

Would this be D-type or J-type?
Click to expand...

Thanks guys. This is a J-Type OD.

Now that I think about it, the Solenoid didn't sound very robust. More like a light click than the sound of a plunger moving. Can I pull the solenoid and engage it to check it's operation?
 
Kjets On a Plane said:
Sure, of course. Pull it. Polarity of terminals doesn't matter.
Click to expand...

I'll give it a try, thanks. This is somewhat of a temporary transmission, so I'm probably not going to pull it again to fix the OD. If I can fix in the car, though, that would be good.

I'm also trying to remember what the pressure relief spring set up looked like, and whether I could have messed up the orientation of the ball/springs, etc.
 
There are several spring/shim configurations within the unloader valve depending on year.

Just the OD comes out with the trans in the car, it's not too terrible all things considered. The top 2 7/16" nuts are kind of a pain.
 
Kjets On a Plane said:
There are several spring/shim configurations within the unloader valve depending on year.

Just the OD comes out with the trans in the car, it's not too terrible all things considered. The top 2 7/16" nuts are kind of a pain.
Click to expand...

We'll see if I can muster some motivation. I'm thinking it must be a problem with the solenoid or the pistons that I removed to check on. I have O-rings for all of it, but I bet I messed up the orientation of some of those small parts. I didn't think I'd be opening up the OD, so I wasn't super prepared.
 
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