Location of Transmission screen Allison M20?

[Blain]

I am changing the oil in my Allison M20 Transmission x2. Manuals says to check yne breather and clean the screen. Pulled off the breather..it looked fine but I am unsure of the location of the screen. There is a cyclinder-like structure on the opposite side of the tranny dipstick with a 1" hose emanating up from it. The manual seems to imply that this is where the screen is located. I

this cylindrical structure does not seem to have been opened in years.. So I wanted to get some feedback before starting the process.

Thank you

Blain

 

[drewread]

I am changing the oil in my Allison M20 Transmission x2. Manuals says to check yne breather and clean the screen. Pulled off the breather..it looked fine but I am unsure of the location of the screen. There is a cyclinder-like structure on the opposite side of the tranny dipstick with a 1" hose emanating up from it. The manual seems to imply that this is where the screen is located. I this cylindrical structure does not seem to have been opened in years.. So I wanted to get some feedback before starting the process. Thank you Blain

Following, as I have to complete the same service in the spring.

 

[SKYCHENEY]

There is a 3 bolt flange. Not sure if that is what you are referring to.

 

[cww]

Curious in this answer myself, I have one that the pressure is slightly low and adjusting the pump doesn't seem to fix it.

 

[Blain]

Here are a couple of photos with one close up..

Thank you

 

[Pascal]

It’s been a while but I m pretty sure it’s under it s the fitting with the three bolts and the hose. Make you sure you have at least one gasket handy, it’s easy to mess the gasket and even a very small suction leak will cause complete pressure loss.

 

[osprey]

Yes that is where the screen (basket) is located. Under the three bolt flange on the suction side of the transmission. the hose will go to the pump.

P

 

[Briankinley2004]

I leave the hose on mine and just remove the bolts to clean. Don’t forget to change the gasket

 

[Blain]

Thank you very much gents. I almost forgot about the gasket.

 

[drewread]

Thanks to all that posted, great info! I think there will be a run on gaskets!

 

[Streff]

I just purchased 2 gaskets for this exact job. Part#5112511. The DD folks called them Teddy bear gaskets. Streff

 

[Blain]

As a follow up, I started the project of cleaning the Transmission screens today, 1/2" sockets to remove 3 bolts then pull the outlet hose up, the screen is attached to it..it's a tubular structure about 4" long and 1.25" diameter. This is my first time doing this cleaning. Actually it was not full of debris.. looked clean to me but now that I opened it up, a new gasket is needed.

I could not pull the screen off or twist it to remove. I cleaned it in place. But as I was scrapping off the gasket, it seems that part of the gasket is under a large washer or such that is attached to the screen. So I am wondering if the screen twists off and the new gasket needs to partially go under the top head of the screen as part of the reinstallation.
The shop manual does not mention how to remove the screen or anything special about the gaskets.

Any insight on how to remove the screen, if that is the case or comments about the gasket would be much appreciated.

Blain

 

[Briankinley2004]

The "washer" is part of the screen. Unless someone put some kind of gasket dressing or something to make it stick it should just separate. Here is a picture of the screen so you know what you are looking at

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[Blain]

Thank you very much Brain for the link. That was very helpful. After seeing the diagram, I have been hard at trying to scrape off bits of the gasket from under the edges of the washer/screen. Unfortunately, the screen is stuck solid. I tried prying it gently with a thin instrument flat head screwdriver with no luck. I am about to use a razor to get under the washer. I have applied a bit of lube, maybe I need more lube and force.

The ironic thing us that it was pretty clean and I did not need to open this can of worms.

Blain

 

[Briankinley2004]

Thank you very much Brain for the link. That was very helpful. After seeing the diagram, I have been hard at trying to scrape off bits of the gasket from under the edges of the washer/screen. Unfortunately, the screen is stuck solid. I tried prying it gently with a thin instrument flat head screwdriver with no luck. I am about to use a razor to get under the washer. I have applied a bit of lube, maybe I need more lube and force.

The ironic thing us that it was pretty clean and I did not need to open this can of worms.

Blain

Can you try using a heat gun to see if it will soften up whatever gunk is holding it in? I bet someone put some kind of gasket dressing or sealant on it

 

[Blain]

Back for an update. I used the heat gun on and off for 4 min which did help. Then I inserted a dash removal tool and tapped on it gently.. finally it gave way. I could not see any gunk but the gasket was heavily adhered to it. It took a bit to clean the gasket off and prepare a good surface for the new gasket.

So thank you all for the continual comments, it is almost all done, still need to get the torque value from the manual to completely be finished.

Blain

 

[yachtsmanbill]

Old black Permatex is the culprit. Get it hot, clean it PERFECTLY then apply the assembly with some red ANAEROBIC sealing compound. ANY leaks will give a vacuum leak to the pump; NO BUENO.