More auto/od problems

[Dieselnut59]

Help! I need more advice on correcting a shift problem on a 1992 350 auto/od. It pulls well and shifts properly from 1st to 2nd, but the engine will govern and it will still not shift from 2nd to 3rd. 3rd to od was finicky, but I adjusted the tps on all 3 of our auto/od equipped trucks, as well as the bands and oil/filter change and everything else works fine, except this truck's 2-3 shift. It has the 4. 10 rear gear and is 2 wheel drive. I use Amsoil in all the auto trannies. Any help is greatly appreciated!

Thanks, John

 

[cerberusiam]

Well, I am gonna make some assumptions and throw out a conclusion and see what you think.



Assumptions:



The 2-3 shift won't happen until the engine defuels or you lift off the throttle



The OD shift happens but only if you have the accelerator positon and speed and you hold your mouth just so



You have adjusted the TV cable correctly





Conclusion:



You are loosing fluid pressure for the 3rd gear apply and it won't overcome the TV pressure as it should. Most common problem is a worn or torn lip seal on the direct clutch pack. A sticking valve in the VB could also be the culprit.



How firm is the 2-3 shift when it happens? Is there any indication of slipping in drive after the shift happens? Slipping or mushy feel in OD?

 

[Dieselnut59]

Assumptions:



The 2-3 shift won't happen until the engine defuels or you lift off the throttle



The OD shift happens but only if you have the accelerator positon and speed and you hold your mouth just so



You have adjusted the TV cable correctly





Conclusion:



You are loosing fluid pressure for the 3rd gear apply and it won't overcome the TV pressure as it should. Most common problem is a worn or torn lip seal on the direct clutch pack. A sticking valve in the VB could also be the culprit.



How firm is the 2-3 shift when it happens? Is there any indication of slipping in drive after the shift happens? Slipping or mushy feel in OD?



Response:

Your conclusions are absolutely right! I am not sure how to correctly adjust the TV cable (I assunme this is the cable that works off the injection pump linkage, parallel to the throttle cable). I did have to replace the return spring for it recently, but took it up the road to test and it was still doing the same thing.



The 2-3 shift is sloppy when it does happen, but I thought that was because it won't occur when throttle is applied, so it just kind of "flutters" into 3rd. Once it is in, you can mash down on the throttle and it pulls great. Sometimes the shift into O/D is finicky, like you described, but it also pulls well in it once engaged. There does not seem to be any slippage.



Breaking (BAD) news!

Today, the mechanic that drives this truck started it up and warmed it a few minutes like I told him to do (in neutral) and went to take off and it will not move at all now in either direction...

I hate to do a total rebuild because this thing was just pulling so well, but if it has to come out, it is getting rebuilt and beefed up!

It has 140,000ish miles and is bone stock with an open service body and single rear wheels. Any final suggestions?

 

["Mad Max"]

For suggestions, if the transmission is going to be rebuilt, there is no question that this is the perfect time to upgrade to a better converter.

Lots of possibilities, but if you're looking for a good upgrade on a budget (like I was a couple years ago), I'd suggest a TCI Truck Master Diesel converter, pn #142250 - can get 'em from Summit Racing for $349. I did mine with this converter and I was on a tight budget, but was very happy with results - big difference in pulling power.



If you have or are going with big power upgrades then you would probably want to go with a stringer converter, from Suncoast, DTT, or ATS.



- M2

 

[Dieselnut59]

Thanks for the help! It is heading to the local transmission shop. This guy has a good reputation and he uses an upgraded torque converter and valve body upon request. We are not adding any power, as this thing serves us well in stock form. I just checked and it has 148,000 miles on it and is all original. If we could get that much again, I would be thrilled. Even a slightly improved transmission should outlast the remaining useful life of the truck, then I'll have a good Cummins engine to put in something else!

Thanks for the help guys! It is these forums and helpful folks like yall that makes TDR so valuable!

By the way, I checked a few things on the truck this morning before we loaded it on a wrecker: The fluid was awful burnt, both black and smelly and I just changed it not even 2,000 miles ago and before that about 10,000 miles before. I also adjusted the bands. When I cranked it to check it this morning, it would pull for a few minutes when first started (in either forward or reverse), then just quit and would not pull again and had a "cavitating" sound in the pan. If I cut it off, then restarted, it would do the same thing, then quit again. Something is obviously blown internally, in the oil pump circuit causing it to lose pressure and bypass. I will let yall know what this guy finds out for me. Thanks again for your help!

John

 

["Mad Max"]

Fair enough . I have to say tho, that I could not believe how much power was lost with the stock converter. The transmission shifted great, but of all the upgrades I have done to my '93, the $350 I spent on the aftermarket converter made the single biggest difference on the trucks pulling power - I couldn't believe how much power bleeds out through the stock version. Just FWIW

- M2

 

[Dieselnut59]

This guy had a "RV converter" that he says is successful. He also uts in improved clutches and a "shift kit". Remember, I am a straight shift kinda guy, so autos are no interest or fun to me! I do wnat this thing to be reliable, but it will not have power or RPM above stock anyway. The guy driving it is used to ricers, so he already thinks it is a rocket!