Hi All,
97 XLT 4.0 code "X" 235k. Having issues with tranny. Twice now while driving (50mph+) I've had the tranny disengage and make a noise similar to an air impact gun like when the lugs come loose. I also have a "bucking" that feels like the tranny is downshifting over and over (buck-buck-buck). I feel this when I let off the gas over 50 mph, under 50 it goes away or I can't feel it. I feel the bucking in the rear end more which has me thinking tranny/u-joints/rear end more than engine.
I changed fluid at 112k, it doesn't look/smell bad. Tranny shifts OK for age. Occasional "O/D Off" light and always have the blinking 4WD HI/4WD LO lights. What do you think? Am I asking Santa for a tranny this Xmas? Or just some stocking stuffers like u-joints?
Thanks

 

There is a code when the lights are blinking of the 4WD. Used search to find them. I read on here about a code when they are flashing.

 

Your 5r55e needs the fluid changed every 35K, so it is overdue x4.

At this stage of the game she is probably gummed up & needs a filter and complaining. Average service life for this transmission is 130K so You have been looked after by the Gods.

Don't overlook worn out U-joints, pull the shaft to check for loose and/or seized.

 

Belated thanks Aquanaut20.
Will service the filter/fluid and see what happens. I'm hoping that since it shifts OK that there's nothing wrong with the mechanics/hydraulics.

 

Vic, does your 4X4 system work - can you take it in and out of 4H? That buck buck buck sounds like when the module is pulsing the A4WD system more than it should. Try putting it in 4H for a minute when it is doing that bucking and see if it stops.

I completely agree with aquanaut that the 5r55 should be serviced every 35K miles. You have been very lucky.

 

Thanks for the reply rrgone. The 4WDoes work but since I last posted the tranny has been removed. Prior to removal I tried a filter/fluid change but I still had the issue of trans whining/disengaging when not under load. The engine RPMs do not change when this happens.
I found a tranny at a yard in a 97 Expy 4.0 SOHC with 90k on it. I have a pushrod engine. Trannys appear to be identical EXCEPT mine has an extra sensor top left just behind the bell housing. I think it is the OD drum sensor. Too bad for me we have the tranny mounted back in the truck. Think it will work OK? Any idea what issues I might have with a missing sensor?

 

So explain to me how swapping in a USED transmission that is much older is going to resolve anything in any kind of long term? If I were you, I would rebuild the old one, and then swap it back in when you get a chance. Or hang on to it till the one you just got kicks the bucket. Since it is basically an unknown, it could be a time bomb, or it could have been recently rebuilt and good for a long while yet. Since the donor was at 90,000 miles, it is not likely to have had a rebuild yet, and is not likely to have ever had a fluid change. But it may still have another 30,000 - 50,000 miles left on it.

If I found myself with two identical transmissions, I would definitely rebuild the one I wasn't using. In fact, you could do the work yourself, which would make overbuilding it an option. Just use upgrade parts instead of regular parts. With upgrade parts, you can make these trannies run 250,000+.

 

Wanted to update you on the outcome of my adventures. We replaced the tranny but still had the grinding noise, and it was very dicey when in reverse, didn't want to move sometimes. CRAP! What are the chances of having the exact same issue with a replacement tranny? Started searching this site for transfer case issues and SURE ENOUGH there are many posts about the exact problem I'm having. The T-case wears and the gears grind. Off to the yard to get the T-case from the same truck I scavenged the tranny from, laying right where I left it. Swap out the cases and cross my fingers, BINGO! All is right with the world. No more flashing 4WD lights, have 4WD capability, shifts well. Replacement tranny does not have the OD Drum sensor and the fix (per TSB) is to connect the sensor wires together to bypass. We modified the sensor by cutting off the back half of the sensor, removed material from around the pins and soldered them together, and sealed the mod. In hindsight we didn't need to cut the sensor if we connected the pins. Many thanks to those who replied and to those who took the time to post about the transfer case issue. Yet another example of this forum at its best. Happy Holidays to all...