20k miles ago, i had my transmission rebuilt. Had a code for a slipping torque convertor.

I bought a Tru-cool transmission cooler and all new transmission lines. (no old junk in lines) I installed all of it, along with a tranny temp gauge. Highest this transmission has ever seen (and i watch it like a hawk) is 165* pulling a 30' TT up a hill in New Mexico.

Normally the transmission runs at around 90-110 degrees in this colder Connecticut weather. Earlier tonight my OD light starting flashing. I'm going to get the codes read tomorrow so i'm still guessing at this point. I wouldn't imagine the transmission running too cold could burn up the torque convertor again?

Anyways, it still shifts into OD. From a dead stop the truck shifts into second hard, and then third a little less hard and then it sort of shifts into OD smoothly. Downshifting is also smooth although it feels like when i tap the brakes the truck starts coasting or something.

I also noticed that when starting from a stand still if i watch the RPMS like a hawk they go up and then drop down between 5 and 6 times before it's in OD? I have no idea what's causing that.

About two weeks ago i thought i noticed the truck was shifting different but i shrugged it off as me being paranoid considering when the transmission was out last. From third gear into OD it almost sounded like it shifted twice?

Anyways as luck would have it i need to be in Florida April 6th to pick up a trailer to bring out to Oregon with this truck. Needless to say i need to resolve this issue immediately.

I'm rambling. My actual question is can i overcool and kill an E40D?

 

Sounds like your tc is bad again, about the overcooling i dought it can damage a tranny ,if all it will shift funny. I have a 6.0 and 7.3 transcooler strapped together and my trucks been fine(mind you I still dont have a trans temp gauge) so no real input from me.

 

Check your fluid level. Yes you can overcool a transmission like anything else they have an operating temperature that they prefer. I usually use transmission coolers with a cold weather bypass, something like a thermostat for your transmission, they typically keep the fluid around 160. The rpm drop is probably normal, the lock makes it feel like it has more gears.... 1st, 2nd, 3rd, 3rd lock, 4th, 4th lock. Which is 5 drops in rpm before you hit highway speed. When you hit the brakes and it feels like its coasting that is also the torque converter unlocking.

 

Same code as before - P1728 - Transmission Slip Error.

Went for a test drive with the guy that built this transmission for me. He had his scanner hooked up the entire time and said it wasn't slipping at all. Said a bunch of other stuff could set this code off besides a burnt up torque convertor. He reset the code for me and told me to drive it around a bit more and see if it comes back.

I pulled the pan earlier tonight for a piece of mind. Took a picture of the magnet and just sent it to my transmission guy. Waiting to see what he thinks about it. All of this is under warranty so it'll all be free to me. I'm just nervous because as i was saying earlier this truck is going to go about 10k miles in the next two months and i want it to perform flawlessly even if i have to pull the transmission back out and get it re-done to ease my mind.

Opinions? 20k miles since rebuild.

 

That does look like alot of debri for 20k, I think the tranny shop used the same tc.

 

Do a line pressure test and then a stall test if the pressure are good.

There's a solenoid that commands the torque converter valve in the front pump on or off. There's also a TC pressure valve in the pump also if I remember correctly.

That's not enough debris to be really concerned, but it is something to keep in mind.

I had that exact same code on a tranny I rebuilt and it turned out to be a stuck valve in the pump burning the clutch up in the TC.

 

Guy that rebuilt my transmission defiantly used a new torque convertor. My old one was smoked.

He replied to my text and said "that's not bad". Drove the truck 360 miles tonight. Lights still off and no odd shifts as far as I realized. Going to drop the pan again tomorrow and recheck the magnet. I figure that'll tell me for sure.

I'm just beyond paranoid of this thing letting go in the middle of nowhere.

 

Did your builder just put a stock reman converter in or at least a triple loc?

 

It was a double disc something. He was talking to me for a solid ten minutes about how he wouldn't even bother rebuilding them if they never came out with a better convertor than stock.

 

I think a slip code on these always is in reference to the converter. Unlocked these don't give enough feedback to figure out slippage internal to trans. Iirc the later units have input and output sensors. These just compare less values so are not as smart. If it set a code and went into limp there is a problem. He can ignore it but it's still there.

 

Codes back.

I honestly think this guy works on so much stuff that half of what he tells me doesn't apply to my truck but some other truck but he truly believes that it's for my truck. I don't think he's trying to be dishonest with me.

He was saying that the sensor on the back of the axle gets a number that is divided by either the tachometer or speedometer or another sensor on the transmission itself to calculate a ratio that is then looked at by the computer to determine whether or not it's slipping.

Anyways, called him back. He wants me to bring the truck to him tomorrow so he can put it on a lift and look at it and get this straightened out. I'm 99% positive the transmission needs to come back out but i'll see what he says. I have no idea if hes just troubleshooting it tomorrow or actually has intentions to pull the trans out for me but we'll see.

All i know is whatever happens needs to happen fast.

 

Thats the problem, he wants to determine a slipping problem by reading a code, the only way to test it would be with a pressure test. Most slipping problem on this transmissions are caused by the TC, not the tranny clutches themselfs, make sure he used the correct trans fluid Mercon V.

 

I put the fluid into it. Used MERC V from advance auto. Was Transmax.

I hope tomorrow he realizes that the thing needs to come out and get re-done.

 

Pressure test won't nessisarily tell you if a tranny is slipping. I had perfect pressures but my TC would slip.

A stall test would determine if the trans is slipping or if the torque converter failed though.

 

^^^ what he said. im no tranny expert, can you explain how to perform a stall test? The more we learn the better