Fluid Drive Transmission Pressure Test

[motard]

Where do you connect the pressure gauge to test the pressure on a 1948 Chrysler Town and Country fluid drive transmission?

[keithb7]

I think this might help you.

 

http://www.imperialclub.com/Repair/Lit/Master/012B/page09.htm

Edited August 6, 2020 by keithb7

[motard]

Thanks. I have this Service Reference Book. It says "Remove the pressure line plug". It then says "that's the upper of the two hexes on the right side of the main shaft rear bearing retainer".  There are three square plugs on the side of the transmission. The bottom plug is the drain, the center plug is the filler, then there is the top plug. Which plug is this Service Reference Book referring to?

[keithb7]

This pic is a spare 1953 tranny I have for a learning tool. The hydraulically actuated piston is situated between the middle the top port holes seen there.

 

It's odd....I have searched through a couple of service manuals. They tell you that the tranny oil pump makes between 38-40 psi. Yet nowhere in the manuals do they instruct you where to test that pressure. They instruct you to jack up the rear wheels. Remove the tranny interrupter switch. Start engine and engage tranny in low range. Accelerate to 8 mph. Watch the hydraulic piston down thru the interrupter switch hole. It should move forward (due to pump pressure). It should move ahead just enough to completely cover the hole. (I assume the hole you are looking into). 

 

Green arrow in my pic below is oil fill port. Red is oil drain port. The top hole with bracket  for anchoring wiring, is for a retaining bolt for the main shift fork. The 2 larger round holes are for shift solenoid and governor switch. Just above those, up by the piston area is a raised part on the flat top of the housing. A vertical hole, about at the center top of the housing seen in my pic. That is where the interrupter switch threads in. You should be able to look down in that hole, from above in the cab. A small floor access panel is likely removable.

 

 

Edited August 6, 2020 by keithb7

[keithb7]

A better pic here perhaps. More complete. 
 

 

[motard]

Thanks. Good pictures of transmission. Can someone tell me where to check the pressure of the transmission? Where do you insert the pressure gauge?

[motard]

On the picture of the transmission shown, where would you insert the pressure gauge?

[Dodgeb4ya]

Test port as shown.... passenger side of trans extension housing...1946-48 M-5 transmission only...

special threaded fitting....

[motard]

Thanks. This was exactly what I needed. Great pictures!! I was able to check the pressure. 

[Dodgeb4ya]

What was your pressure reading?

[keithb7]

Just to confirm this pressure test port is only on the 46-48 M5 tranny? Not any years of the M6?

[Dodgeb4ya]

There is no oil pressure test port on the M-6 transmission...why I don't know.

The test involves

*Raising the rear end, 

*Removing the interrupter switch above the shift piston...

*Starting the engine...putting it in gear...

*Run it above 13mph in gear...

*Look down hole at the shift piston..

*Piston should move forward to complete upshift above 13mph in high range...

*Test completed 

[MarcDeSoto]

This is a good filmstrip from 1949 on how to troubleshoot the M-6 transmission.  To address your problem, skip to 8:00 minutes in.  

 

http://www.mymopar.com/index.php?pid=382

[motard]

The pressure of my 1948 Chrysler Town and Country Convertible Coupe transmission was exactly 40 psi at 14 mph in third gear.