Moved my 34' 5th wheel two weeks ago; really pushed my 88' non turbo to the limits backing and maneuvering her into her new spot.

Well, 2 weeks later, I go to use her and sometimes she does not start out in 1st gear from dead stop; I have to manually shift her into 1st, then 2nd, then 3rd.

AND.....sometimes she does not shift into 3rd, but just slips/free wheels. Sometimes when I manually shift from 2nd to 3rd, she jumps right into 3rd and drives fine.

AND.....a couple of times when manually shifting from 2nd to 3rd, she went back into 1st.

I removed and drained the pan. There was a lot of grey metallic residue on the magnet and the fluid was brown burnt looking. Tranny has about 35K on rebuild(got receipt of tranny rebuild when I bought the truck couple years back). So I replaced the fluid I took out, 5 or 6 quarts; and she still ran the same.

It doesn't seem that clutches or bands are blown because she runs fine when in gear. Could it be that there is dirt/junk within the valve body? Anyone run into this type of problem?

She's a 2wd/c6/7.3 non turbo/all stock truck/ 180K with 35K on tranny. Thanks in advance for any help/advice.

 

Is there fluid in your modulator line? If so its toast.

 

Is that the vacuum modulator at the back of the tranny; controls shifting?

 

Yes back on the right side, pull the vac line and look for fluid in it.

 

Thanks, will do Mon afternoon.

 

I think you are going down the same road I did.... and I toasted my C6 because of it!


DO NOT DRIVE IT TILL YOU FIND OUT WHAT'S WRONG!


Mine to started revving really high before shifting out of 1st, and gave a weird shift into 3rd.

Drove it on the highway for 3 hours before noticing the back wall of the camper covered in tranny oil, and a weird burnt smell.


Got home, backed in the driveway, and next morning....did not like what I found when I pulled the dipstick!



black/brown god awfull smelling tranny fluid about 1 quart low, from leaking out the dipstick seal on the tranny, got so hot it started leaking out of it.


And now it killed the pump, so next spring I have to pull the tranny out of it.


Still runs/drives normal even with a dead pump, doesn't slip, but waits a long time to shift, and shifts hard as hell!

I drove it from home to winter storage (10 miles) and it did fine.


What a tough C6 that is! To bad the pump died.


I replaced the vacuum modulator thinking it might be fine, and nope, pump is dead, not completely, but to dead to drive far. Drove fine for 2 min with the new modulator, then started acting like before, high rev shifts, etc. Guess it popped again.

 

Haven't had the chance to check my vacuum line to modulator yet. But I sure hope my tranny isn't fried!!

 

Alright, checked my vacuum line to modulator and it's dry! So what should I do next? Any tranny tech's out there?

 

Hmmmm, then maybe working it hard like you did dislodged crap inside the tranny and screwing with the governor.


Get to an appropriate place, throw in Reverse, and go as fast as you can in Reverse! Do that a couple times.


That will flush out the back of the tranny and clean the governor.


Then I'd recommend a good tranny flush (engine running style).

Dropping the pan only gets about half of what's actually in there. The torque converter holds half the fluid.


Also, if the fluid was bad looking and burnt with only 35k on rebuilt, seems like it doesn't have proper cooling. Install a Aux. transmission cooler if there isn't one already, or upgrade to a bigger one! A good size would be 10x10" or in that area.


Even bigger if you tow.....



And heres what i'm talking about doing a tranny flush, engine running style.

---------------------

Drop the pan, change filter etc.

Reinstall pan, fill back up to capacity.

Start 'er up and let 'er run for a couple minutes. Shift through all the gears a couple times.

Now get a 5 gallon bucket and a piece of rubber hose.

Disconnect the trans feed line from the radiator (or aux cooler) and shove on the rubber line on that and aim the rubber line in the bucket. Tape the line to the lip of the bucket so it doesn't come out while it's flushing.

(to find the feed line, disconnect both lines to the radiator and start the engine for a second, witch ever line squirts out fluid is your feed line.)

Give a couple shots of compressed air through the radiator (or aux. cooler) to send all the old fluid and crap out of that and back to the transmission.


Put a good funnel on the transmission dipstick tube.


Now prepare at least 10 *OPEN* quarts of ATF ready, at easy hand reach.


Fire the engine up, and start pouring the ATF down the dipstick tube, and don't stop! As much fluid will be coming out as you are putting in.


When the fluid coming out and dumping into the bucket looks as nice and clean as the fluid you are dumping in, stop the engine.

Reconnect the feed line to the radiator (or aux. cooler). Make sure BOTH lines are well connected.

Start up engine and check level. Add as needed. Make sure level is correct.

Go for a good drive, when you get back, check level again and your done!



Simple as that! I do it every single year on my motorhome.

It's a good idea to be 2 people doing this, one sitting in the drivers seat of the vehicle waiting for commands by the person doing the work outside, just incase something happens that you need to turn off the engine quickly. You don't want your transmission to run dry.

 

I sure hope that'll fix my trans problems. I already have a 10 x 12, or 14 aux tranny cooler I installed when I got the truck.

So I gun it in reverse and get to maybe 15 mph? For how long do I hold this speed; or just get there and hit the brakes to a complete stop? (That's funny, but I live in a hilly area and when I went down the same hill like 4 times, came to a stop, then took off again, my tranny shifted fine from 2nd to 3rd. Then I could manually shift between 2nd and 3rd and the trans would engage each gear perfectly. )

Hopefully there's just dirt trapped in the governor, like you said.

 

ATF has a recommended life of 12k mi. If you get it over 220* cut that in half, over 230* cut that in half again.

 

So, since my atf is burned, could that maybe be part of the problem? and idijohn's way of flushing could solve my prob?

 

Johns way of flushing should do you good, if it smells burnt it is burnt and is doing damage anytime you try running it, so id do the flush, and an aux cooler is a must, its harder then you think to keep that beast cool, if you plan on towing get the cooler and a gauge.