Engine/Transmission (1994 - 1998) Converter slip and intermittent overfill

[JoeBioDiesel]

I have a fair amount of trans overhaul experience, but certainly not a Dodge expert. My truck is acting a bit wierd lately. Yesterday after about 70 miles of 75+MPH driving I exited the interstate and started driving 60MPH in stop and go traffic. A few miles into that the trans started to slip in 4th/lockup. Downshifting to 3rd made no difference. All foward and reverse gears were OK, but I only got a partial TCC apply. I stopped and checked the fluid level (trans temp was normal 135F, I've got a gauge). The fluid was very overfull and foaming. I shut it off and checked to see if the cooler lines and cooler were working... seemed OK, no cold spots. I started the truck and drove away. It shifted normally... I stopped and rechecked the fluid... it was only slightly overfull and way less foamy.



I understand it's impossible to gain and lose fluid in a closed system, so what happened? I'm guessing that the extra fluid was coming from the converter, and maybe it wasn't filling like it should... just a guess though. It has happened several more times after driving extended periods at high speeds and then exiting the interstate. Each time I stop, it's overfull, I shut it off, and then it's fine. Each time it slips the trans is overfull and foaming. Each time it cures itself the fluid returns to a normal level. I verified the trans temp with an infrared temp gun. It's OK. Fluid is not burned, and I've driven about 400 miles since it started acting up.

Any guesses? All input appreciated.



Joe

 

[bmoeller]

Internal TC leakage?

 

[Extreme1]

I'd guess that the foaming fluid is the overfill. If foamed enough, it might cause a pressure loss (sucking air) and allow TC slippage. Try rigging a pressure guage and watching it.



How fresh is the fluid? Dodge service interval is 15,000 miles on these trucks.

 

[JoeBioDiesel]

I did a complete fluid exchange with the Mopar fluid about 10K ago. I'll try bleeding a little fluid out of it and see if it improves. If I drive the truck locally, in town, at speeds around 30MPH until it warms up, the fluid level shows "max" on the stick. Maybe that's too full, but funny it wouldn't act up until now. It's worth a try though.

Joe

 

[CHardin]

It sounds to me like you have an air suction leak causing the foaming and overfill condition. Is it possible the filter is installed incorrectly, or that the valve body may have some loose bolts? How about an air leak in the return line from the radiator? Something is causing that foaming. Charlie.

 

[BarryG]

A while back I had an experience with my trans. It was leaking like a sieve while running. When I went to check the fluid level it was way overfull I had done a fluid change about 5k previously and knew darn good and well how much fluid I put in, I was stumped. I pulled 2 quarts out and still a bit overfull. The leak was caused by the front bushing having worked loose and was pressing against the front seal allowing it to leak. The over fill was due to the front pump not pumping fluid enough so much of the fluid was in the pan instead of circulating. . I had very low pressure once I got it tested. Might be worth checking your line pressure to see if the pump is a pumping. It drove just fine until the pump really crapped out in the repair shop parking lot which I had just driven 250 miles pulling a trailer to get there. My temps didnt climb much either until about 15 minutes before I got there and then they just slowly went up to about 190 and hung there.

 

[JoeBioDiesel]

Well, it's not an electronic problem. I monitored the voltage and amperage on the TCC apply circuit. It behaves at it should. I get . 125V and 210mA on the control line from the solenoid to the PCM. Nothing wrong with that and it doesn't change from when it's working normally to when it goofs up.



Charlie- doesn't the filter pick up at nearly the same height as the hole in the valve body? I don't remember these having a pickup tube on them like some other brands... but I might be wrong, that's why I'm asking. My trans pressure gauge was reading 0 psi when I put it on. I couldn't figure out what was wrong for a while. Ends up the gauge is bad. It's not that old either.



Barry- I hope the bushing hasn't spun in mine. Did your problem get worse when it got hot, and better after it cooled? I'm going to pull the pan tomorrow and check the valve body bolts and refill it. Unfortunately I won't be able to get the Mopar fluid tomorrow. I guess a few qts of Dextron won't kill it.



Thanks everyone for your help so far.

Joe

 

[BarryG]

Joe I was out in the middle of BFE big time when I noticed the leak. HAd to drive 250 miles to albq to get to a shop that could deal with it properly. I got to ALBQ no problem even with the trailer. I stopped at the only gas station around and bought them out of fluid. I figured as long as it had fluid in it and it would go what the heck. I sure as heck wasnt looking forward to a 250 mile tow bill. I stopped every 30 minutes and checked the level. Trans gauge showed a slight increase in temp on the way to Albq but only 20 degrees or so and was still running under 170 unless going up a hill then it would climb up to 180. After a while the bushing had walked itself somehow underneath the lip of the seal and stopped the steady leak to a minor drip( tech said it was darn near welded on there). However as I dropped off the trailer at a relatives house in Albq and headed to the shop the temp went to 190 and stayed there the rest of the way to the shop(10 miles). I parked in the shop parking lot went in had to a wait a few then was told to pull into the garage. The truck would not move from that spot for problably 2 minutes then just barely. After about 4 minutes it seemed back to normal ( well I could at least hear and feel it go into gear)and drove it into the bay. Thats when I found out about the pressure being so low like 25psi. He called me later and let me know what all had happened after he tore into it. Cant really answer your question. I found the leak just before dark on tuesday. Went to Albq weds morning was in the shop by 1pm. It never had a chance to cool down once I started.

 

[JoeBioDiesel]

I got a chance to check the pressures today. The line pressure when measured at the front accumulator should be over 100 PSI when in lockup and half throttle. It's not. It was only 80 psi. If I yank the throttle cable all the way out and drive it, the problem disappears and I've got about 120PSI. The problem gets worse as it warms up because the pressure drops a bit when it's warm. I don't know why it's foaming yet, but tomorrow I'm dropping the valve body to check/retorque it, and I'll bump the pressures while I'm in there.



Joe

 

[JoeBioDiesel]

I took the valve body out last thursday to check it out. I found that the bolts on the solenoid pack were backed out, allowing them to leak. i tightened the bolts, and retorqued the valve body. I also bumped the main line pressure about 25 PSI while I was there. After several hundred miles, it is still OK... so it looks like I found my problem.

Thanks everyone for your help.

Joe