Hi all,
We have recently had an intermittent problem where, when I put the truck in drive after backing out of a parking spot, the truck lurches forward and then stalls. Then, when I put it in neutral and fire it back up and put it back in drive, it charges forward, and I'm hardly able to hold it with the brakes. But then, when I put it into park and turn it off and turn it back on, it's fine. It seems as though the torque converter is locking up when I put it in drive after backing up. The truck went to the dealer for diagnostic of an unrelated issue, and they said that it happened to them as well. They believe the trans is on it's way out, but it didn't throw any codes, although they remarked that they fluid smelled burnt, even thought it was changed about 7k miles ago. Has anyone else ever heard of this? It's a 2003 F250 with a 7.3 and a 4R100, 185k miles. Thanks!

 

I would guess that the burnt fluid could be a result from this abuse your transmission is going through. When you're in gear at idle the only thing in the transmission that's spinning is the pump. So when you put it in drive, your malfunctioning torque converter is locking the rear axle which isn't spinning with the engine which is. That's just like revving the engine to shift into gear. My WAG is that this could be causing your burnt smelling fluid. Of course I could be completely wrong, transmissions mystify me.

The problem with your torque converter could be either electrical or a failed torque converter. Considering how this only does it under certain circumstances I think it's an electrical issue; your torque converter doesn't care whether your transmission is in forward or reverse. Have you had your truck scanned with a good code reader that's capable of reading transmission codes?

 

The usual causes of the torque converter locking when it shouldn't are: (on order of likeliness)
Low trans fluid
Loose/missing/leaking internal filter
Worn seals
Worn pump
Short in the TCC solenoid wiring
Bad TCC solenoid
Bad torque converter

 

I think you hit it right on with the worn seals. This thing has had a stock cooler on it for 165,000 miles, and I know it's been overheated on more than one occasion, so the seals are probably shot.

 

what temp is considered overheated? mine has been hitting 206 lately

 

I think the general consensus is that anything above 220 is bad, and that anything about 190 for extended periods of time is also no good.

 

Anything below 220F is fine. There is no reason to worry about 190F. Someone just made that up.

 

Sounds like it's time for a tranny/TC replacement or rebuild. The TC has always been a weak link in that tranny. I went with a www.suncoastconverters.com rebuilt tranny and TC; it made a world of difference on my 2002 and it was going strong when I sold mine at 185k.

 

Okay. How long do you guys think we have before it starts to really fail? We are driving it to Jackson Hole in a couple weeks, about a 1,500 mile round trip. It will be unloaded except for some people and bicycles. Should I be concerned about it?

 

Yes, I would be concerned. It's one thing to drive a couple hundred miles on a "maybe" tranny, but 1500 miles to Jackson Hole? Forgetaboutit, no way if it was me. If the tranny does explode, you will have so much crap in your lines that you'll never get it all out even with extra tranny filters. Much better to bite the bullet and get a bullet proof tranny anf TC from Suncoast and coast for another 200k without a worry, IMHO.

Pap