Guest jumpinjimmy Posted April 13, 2012 Share Posted April 13, 2012 I just got my 1950 DeSoto and was taking it on a ride and suddenly the transmission seemed to go into neutral. I didn't move the shift lever but was simply cruising along. Up until then, the tranny had run through it's gear changes just fine and the car was running well. The engine would rev, but the fluid drive wasn't engaging. I pulled over, put the shift lever into Low gear and was able to proceed. It ran fine for another mile and then did the same thing over again, seemingly in neutral and engine still running but no power to the transmission. Anyone have any ideas they can share?? Link to comment Share on other sites More sharing options...
c49er Posted April 14, 2012 Share Posted April 14, 2012 (edited) Check the M-6 trans fluid level-right side of trans. A ID plate above it says use 10W oil only. Oil level full is to the bottom of filler plug hole.The other part that confuses new Fluid Drive owners is the "Fluid Drive" coupling-is NOT a torque converter, it is only a simple fluid coupling with a clutch and presssure plate attached and is separate from the transmission and enclosed in the bell housing. The pass side floor mat needs to come up and there is a oval metal cover with 2 phillip head screws holding it to the floor. Under it is access to the bell housing with a metal round plug. Remove that and then you can rotate the FD coupling until the 3/4" hex fill plug lines up with the hole. CAREFULLY remove the plug, don't drop it in the bell housing! Hopefully your FD coupling oil level is full. It was filled from the factory with MoPar fluid drive oil-NA anymore.Use use 10W motor oil or TDH tractor fluid, ISO 22 grade. If you can`t get ISO 22 get ISO 32. I don't mess with the fluid coupling other than just making sure it's full of oil.Bob Edited April 29, 2012 by c49er (see edit history) Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted April 14, 2012 Share Posted April 14, 2012 Bob, thank you very much. I'll check on that as soon as I can lay my hands on 10w oil. Here's a photo of my new machine. I purchased it on ebay and had it shipped to me so never was able to test drive it. Not as good as described, naturally, but not bad. Steve Link to comment Share on other sites More sharing options...
Rusty_OToole Posted April 14, 2012 Share Posted April 14, 2012 If you check your Fluid Drive oil level, stuff a rag around the hole and you will not drop the plug where it should not go.Once you are sure there is enough oil in the trans and fluid drive, check over your wiring for loose, frayed or broken wires.There are other things you can do, we can go into all that if you still have problems. If you do a search for Fluid Drive in the Chrysler section there were some long threads in 2008 with a thorough discussion of the operation and servicing of this tranny. Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted April 15, 2012 Share Posted April 15, 2012 Firstly, thank you so much for taking the time to respond to my appeal for help. Your knowledge is really appreciated and thank you again for sharing. I've tried to find the 10W oil and have come up with ISO 22, which depending on which website you look on can be either 5W or 10W. Do you think this will work? I've had a look at the wiring and it seem in good shape but I'll check contacts to be sure if adding fluid doesn't help. Link to comment Share on other sites More sharing options...
skyler Posted April 15, 2012 Share Posted April 15, 2012 jump, i always used hydraulic jack oil in my 1951 windsor. it is a light oil and has anti-foam quality. my unit leaked so i needed something easily available. it works just fine. love the grill on that desoto. skyler Link to comment Share on other sites More sharing options...
Rusty_OToole Posted April 15, 2012 Share Posted April 15, 2012 The ISO 22 will be fine. Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted April 29, 2012 Share Posted April 29, 2012 I finally have gotten around to checking the fluid in the transmission and when I took the filler plug out, expecting it to be low, it flooded out, obviously way overfilled, and I noticed the odor of the oil was very similar to dextron auto transmission fluid (there was even a reddish tint....I think it was a mixture though). I went ahead and pulled the lower plug and drained it all out and am going to replace all of the fluid and see what happens. Link to comment Share on other sites More sharing options...
JohnGB Posted May 2, 2012 Share Posted May 2, 2012 If you have the wrong oil in the unit, or a mix of oils that is incompatible, it might be starting to foam up when it gets hot, which of couse would kill the proper operation Link to comment Share on other sites More sharing options...
Guest Fosbreed1 Posted May 2, 2012 Share Posted May 2, 2012 NewbieI recently purchased 10W ND (non-detergent) motoer oil from O'Reillys for $3.99 per/qt. It seems to be a good and fairly priced source for 10W ND Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted May 2, 2012 Share Posted May 2, 2012 I will check out OReillys as the iso22 that I have found is pneumatic oil and seems rather thin. I'm shocked at how overfilled the gear box was and wonder how they added so much fluid.....would that have been from the filler hole on the top that is accessed from within the car?? Is it possible to fill from gear box from where I have access to the fluid coupling?? Link to comment Share on other sites More sharing options...
jazzer3 Posted May 2, 2012 Share Posted May 2, 2012 No, the fluid coupler and the gear box are separate, I have been using 20 wt. non-detergent oil in the transmission and tractor oil in the fluid drive unitJay Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted May 3, 2012 Share Posted May 3, 2012 Hello again, Please could you have a look at the photos below.....I drained the transmission and added new oil. I also had a look in the top filler plug (accessible from inside the car) for the fluid coupler, and I cannot see anything on the inside that may have a another filler plug. It does look damp....but I can see no standing oil there. However, I also took the time to clean the contacts on the solenoids and the transmission is now staying in gear properly. Can anyone tell me whether or not I should add oil to this top filler plug before I batten down the carpeting again. Once again, I see no possibility of another filler plug to fill. CLICK ON IMAGE TO ENLARGE Link to comment Share on other sites More sharing options...
Rusty_OToole Posted May 3, 2012 Share Posted May 3, 2012 (edited) I don't know what that picture is, but it isn't the Fluid Drive. The Fluid Drive unit looks like a torque converter. It is inside the bellhousing.To get at it, look for an access hole on the right side of the transmission tunnel under the instrument panel. Roll back the carpet from the front. You will find a plate in the floor held down by screws. Remove the plate. Under it, you will see the bellhousing. It should have a round knockout plug. Pry it out. Inside, you will see the Fluid Drive. If the fill plug is not visible, "bump" the starter until it comes into view. Stuff a rag around the hole. Unscrew the plug. If you can see or feel the oil, it is full. If not top it up. Chrysler says you never need to change the oil in the Fluid Drive. Whether they contemplated them lasting for 50 years I don't know.If you had done a search like I told you, you could have found out all this in minutes and saved me typing it all out again for the fortieth time. Edited May 3, 2012 by Rusty_OToole (see edit history) Link to comment Share on other sites More sharing options...
Rusty_OToole Posted May 3, 2012 Share Posted May 3, 2012 The thin, ISO 22 oil is ideal for the Fluid Drive. The thin oil reduces friction and improves the performance of the Fluid Drive. It works by pressure not by the thickness of the oil. Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted May 3, 2012 Share Posted May 3, 2012 @ Rusty oToole---The picture you are looking at is taken through the access hatch on the right side of the transmission tunnel from inside the car -- passenger side.....so you can see why I am confused. Sorry you had to re-write this, but it seems my explanation is clear is saying that I'm not seeing what you say I should be seeing....which is why I included photos. An earlier posting by 49er says it should be on the passenger side and you are saying under the instrument panel, which for me means driver side. I'll look for another plate to remove....I didn't take out the entire carpet as I thought the plate I found was the right one. Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted May 3, 2012 Share Posted May 3, 2012 Gonna look further forward near bell housing under dash, perhaps there's another plate that I didn't see earlier. Link to comment Share on other sites More sharing options...
Guest jumpinjimmy Posted May 3, 2012 Share Posted May 3, 2012 Found it, smaller plate near the bell housing. it was full. Thanks everyone. Link to comment Share on other sites More sharing options...
c49er Posted May 4, 2012 Share Posted May 4, 2012 Another picture of the M-6 Transmission Fill and Drain plugs....Bob Link to comment Share on other sites More sharing options...
Guest 5Wbob Posted May 5, 2012 Share Posted May 5, 2012 Thanks to everyones conversation about servicing the transmission with 10W motor oil.I now know where to start looking for the oil.Bob Link to comment Share on other sites More sharing options...
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