Hot Muncy Trany Normal?

[Joseph K.]

I have a M 21 in a 69 with a 350 motor. When I bring the car back after a short 15 mile run the trans is hot to the touch, probably about 180-190 degrees. I removed the trans about 500 miles ago and cleaned it out, replaced the seals and then placed 90 wt oil up to the fill port. Any idea if this is correct or should the trans be cool after a short run?

[Joe L.]

Re: Hot Muncy Trany Normal?

I have a M 21 in a 69 with a 350 motor. When I bring the car back after a short 15 mile run the trans is hot to the touch, probably about 180-190 degrees. I removed the trans about 500 miles ago and cleaned it out, replaced the seals and then placed 90 wt oil up to the fill port. Any idea if this is correct or should the trans be cool after a short run?

Joseph-----


You can fully expect the transmission to be relatively hot after the car has been run for awhile. Heat is transferred from the engine as well as heat generated by friction within the transmission. Using synthetic trans oil like Red Line seems to reduce temperature in my experience.

[Joseph K.]

Re: Hot Muncy Trany Normal?

Joseph-----


You can fully expect the transmission to be relatively hot after the car has been run for awhile. Heat is transferred from the engine as well as heat generated by friction within the transmission. Using synthetic trans oil like Red Line seems to reduce temperature in my experience.

Joe L,

What is the wt of the synthetic oil and where do you find it?

Thanks

Joe K

[Joe L.]

Re: Hot Muncy Trany Normal?

Joe L,

What is the wt of the synthetic oil and where do you find it?

Thanks

Joe K

Joe-----


Use 75W-90NS. Go the Red Line Oil site and they have a dealer locator feature by ZIP code. www.redlineoil.com

[Jephrey S.]

Re: Hot Muncy Trany Normal?

Another thing that you could check is the exhaust splices adjacent to the transmission.
I did not have problems in my 70 with the M21 after 15 minutes, but after 45 minutes of driving the shifter knob would be uncomfortable to touch. After an hour, it was downright painful. This was also coupled with excessive heat in the cockpit that installing insulation under the carpet did not change. Eventually I found that I had an exhaust leak at one of my splices adjacent to the transmission where they pass through the frame. Re-seating the joint helped the heat problem, and replacing the exhausts eliminated it. It is easy enough to check; just look for soot extending away from the joints. I never had any soot on the transmission, but did have noticeably more soot at one joint than at the other.
I did not have a problem after only 15 minutes, and I think that you would have mentioned the noticeably hot shifter, so this is most likely not your issue. I would expect the transmission to be reasonably warm after 15+ minutes of driving. Still, I threw this out there just in case. Good luck.

[Jerry G.]

Re: Hot Muncy Trany Normal?

In the road race car I use a full sythetic as Joe recomends. In my case I use Valvoline. The transmision is an M-22. I use temperature monitoring tapes on all the critical cpmponents and the transmission never gets to 200 degrees. This is with over 500 HP going through it under road race conditions. Jerry

[Joe L.]

Re: Hot Muncy Trany Normal?

Another thing that you could check is the exhaust splices adjacent to the transmission.
I did not have problems in my 70 with the M21 after 15 minutes, but after 45 minutes of driving the shifter knob would be uncomfortable to touch. After an hour, it was downright painful. This was also coupled with excessive heat in the cockpit that installing insulation under the carpet did not change. Eventually I found that I had an exhaust leak at one of my splices adjacent to the transmission where they pass through the frame. Re-seating the joint helped the heat problem, and replacing the exhausts eliminated it. It is easy enough to check; just look for soot extending away from the joints. I never had any soot on the transmission, but did have noticeably more soot at one joint than at the other.
I did not have a problem after only 15 minutes, and I think that you would have mentioned the noticeably hot shifter, so this is most likely not your issue. I would expect the transmission to be reasonably warm after 15+ minutes of driving. Still, I threw this out there just in case. Good luck.

Jephrey------


That's another possibility. Plus, it's EXTREMELY IMPORTANT to check out and eliminate any exhaust leaks in this area. Leaking exhaust has MAJOR SAFETY RAMIFICATIONS at this location since it can easily "intrude" into the passenger compartment.

[Joseph K.]

Re: Hot Muncy Trany Normal?

Thanks I will check for leaks and try the synthetic oil

Joe