transmission woes

[cummins250atDpoint]

93D250 4x4... intercooled 4spd at,125,000 ,miles.
overdrive has a hard time shifting in and also wants to shift down at lower speeds,40 or so. this seems to be temperature related as it is worse when its cold out and it seems to stop when the temps outdoors is say, 60 or above or the truck has been on the road for awhile (a good while i might ad)! when it is cold i have to feather the acel or simply just PUT FOOT IN IT ! it has the cooler in front of the rad and it has and additional cooler under truck with an elec fan. the oil has been changed (oil and filter from dodge) and the filter was clean as a pin! one more thing,if this machine sets for awhile it also has a symptom of when transmision is first enguaged it takes a few seconds for the clutches to grab, as stated before... temperature related also !
does anyone have any suggestions ?

 

[fastmark]

my 92 was having this same problem at 125k. I thought it might be the TPS sensor not telling it when to shift. When I had the transmission rebuilt, they found the seperator plate almost wore in two at three places! those little steel balls wore the plate out very badly. Mine shifts fine now. You can drop the valve body without overhauling the transmission.

[This message has been edited by fastmark (edited 03-10-2001). ]

 

[GeneH]

All of my overdrive problems have been related to the TPS(not wanting to shift into overdrive or shifting in and out of overdrive).
The delayed transmisson engagement if the truck has sat for a day or two is normal. The torque converter fluid is draining back into the transmission pan. I start my truck in nuetral, this way the transmission fluid is circulating through the transmission as soon as its started, if its started in park the fluid will not start circulating until its put into gear or into nuetral. If you still don't care for the delayed engagement there is a TSB out on this 21-08-94. There is a drain back relief valve put in one of the oil cooler lines that will prevent the torque converter from draining.
Gene
92 350 4x4

 

[Paul Herioux]

Is your thermostat operating correctly?
The PCM(powertrain control module) monitors engine temp and locks out overdrive and lockup below preset temps(would list but can't remember off top of head, must have something to do with heat loss from lack of hair). I have seen a couple of truck at the shop bopping in and out of o/d because of t/stat cycling. These have been 2nd gen trucks but I believe the 1st gens used the same programming. I also would check the TPS adjustment and function. Voltage should be at 1. 00V at idle and should increase smoothly up through 3V+ at WOT.
Hope this helps.

------------------
89 w250, 47rh trans, cleaned up exhaust, Dynomax bullet muffer, 3" lift

 

[cummins250atDpoint]

thank you for your replies guys... looks like a good place to start would be to go to cummins and obtain myself a trustable thermostat and if that dont do it then the tps volt range was going to be my NEXT question #ad

other than this certain problem im having... ... are these rig's "THE BOMB" or what ! i swear i feel like the MAYTAG repairman when i open up the hood on this thing !lol at first glance when i bought this rig i was not aware that it had so many bells and whistles as far as elec controls were concerned. i am a mechanic by trade and do get to do some work on b series engines in wheel loaders and cranes and such... same animal just VERY different control systems !
just by reading the postings on this board im very excited to start doing some digging under the hood and maybe some tweeking of my own. anyways thank you guys and common since tells me im probly looking at a more than likely "simple" problem with the overdrive thing #ad

 

[Bill Kondolay]

You are getting good advice here,
the two places i start with these symptoms is the tps and the transmisson temp sensor.
Since it seems to work fine when the trans. is up to temp. the logical place to start is the temp sensor or engine thermostat.

Bill Kondolay
Diesel Transmission Technnology