View Full Version : Slipping transmission???

06-24-2008, 05:28 PM
Hi all, I just completed my first major excursion pulling our BH 3055 with our '99 F250 Diesel. I pulled up and down the Black Hills (primarily hwy 16 south of Rapid City). There were some pretty long 6-7% grades and for whatever reason my transmission temp gauge chose this trip to stop working although the EGT gauge was fine. Anyway we made it up and down the hills but on the way home I was pulling out of an overnight stay in Winona MN up a very short but very steep grade. On the way up I had the sensation that my back wheels were slipping as if they were intermittently catching some gravel and slipping. What bothered me was that it seemed a little too regular to just be catching a few patches of loose road. It very briefly did a similar thing once more before we got home. So..... my question is this: Has anyone else had an issue with a transmission starting to slip like this maybe because it has been overloaded? Does this seem plausible that a transmission can start having this type of problem and if so, is it doomed to get worse? I have always known that the 7.3 diesel was almost bullet proof but the transmission in that model was the weak link if there was one. Any information would be appreciated. By the way, the truck seems to drive normally unloaded and I had no issues pulling the BH on more level ground. Thanks, Pete

06-24-2008, 06:01 PM
If it is slipping, I wouldn't pull again till you address the issue. In my mind it sounds like your close to smoking the clutches. You could have a builder up the pressures some, but I suspect most will want to do a rebuild at this point. I would also get the fluid changed asap.
I have had an ATS upgrade, and a DTT upgrade done to our tranny, and honestly I wouldn't recommend either. It sure dont slip but when it shifts it SHIFTS.

06-24-2008, 07:50 PM
I had a similar problem develop with my 2001 F-350 pulling a SOB fiver. it started out as a little slipping then went to slipping in reverse, then gave out all the way on our way home from our trip. I had to have the truck and trailer towed home. The tranny was totally smoked.

During the rebuild, I had a Suncoast torque converter installed, it is the weak link in the Ford tranny. I've been having the fluid changed every 15K miles while towing. I also installed 2 hugh transmission coolers (about 80K of cooling). My tranny temps now stay around 160 to 170 while towing.

Good Luck!


06-25-2008, 08:59 AM
Well guys, that was not the answer I was looking for. Something more like "Come on Pete, you're making way more out of this than you should" would have been nice. But seriously, it does raise two questions. First, if it came to rebuilding the tranny, what kind of ballpark price are we talking here? But what I'm struggling with even more is what would I do with it right now? As I said, it seems to run just fine in most cases. How would they diagnose a problem that happened briefly once or twice under extreme load? I can't imagine there are any reasonably priced diagnostics that they could slap on my tranny to verify a problem right now. And I'm certainly not going to have them tear down my tranny on a hunch. It almost seems that I have to have something a little more substantial to even bring it to a repair shop. Am I missing something here? Thanks.

06-25-2008, 12:11 PM
Smell the fluid -- if burned you will know. Also look at color it should be nice clear red not dark. Both are good indicators of trouble or imagination.

06-25-2008, 12:58 PM
Thanks Jim. I will be having the tranny fluid changed out in the next week or two and I will ask them to look closely at the fluid coming out. I also need to see what I can do to get my tranny temp gauge back on line. It picked the worst time to go south on me. Pete

Forrest Fetherolf
06-25-2008, 01:04 PM
Do as alkyspeed suggested or go to a tranny shop for a diagnostic opinion. If the fluid smells burnt, the damage is done, most reputable tranny shops will not recommend changing the fluid. If you are still not convienced..............drive it until it drops. The worst that can happen is getting stranded in the middle of nowhere or limping to a shop or home. I would not run the risk............you are best served to control the environment for necessary repairs. When these symptoms occur.............it is a sign of more problems to come. Depending on where you go, the cost could be $2k to $4k. If the truck is worth keeping, you might consider "beefing up" the tranny to help minimizing this problem again.


06-25-2008, 01:54 PM
Just pull the dipstick. Check color and smell. Next step would be to check the filter, and drain plug if yours is magnetic.

Pete, here is something to hope for. Today we were pulling seriously hard up a big hill and our transmission sounded like it was slipping on and off. Note that I said "sounded", your deal was fresh in my mind so I was watching the tach, and it was steady. What was happening was it was an audio thing, sound was bouncing off trucks and rocks and things, and made the truck sound like it was revving up as we went by them. Its a slim chance, but thats all I got.

In our dodge we can get rebuilt for 3k or an upgrade for 5k plus depending on what parts you put in. I'm embarrassed to tell you what I got in mine.

good luck

06-25-2008, 06:25 PM
Pete, take to the shop and have them drop the pan and change the filter, you did not mention how many miles have been put on the tranny since last service. Could be the filter is partially clogged and not providing enough fluid in a stress condition. Once then have the pan they will see any serious metal loss on the clutches, some is normal. Like these guys said if it smells burnt you most likely have a clutch problem. Sorry it is not going to cure itself :( but possibly if changing the filter and fluid you may get back to normal. ATS builds some really fine bullet proof trannys and coupled with a good torque converter the difference can be amazing. It's only money brother :)

06-25-2008, 07:08 PM
My rebuild with the Suncoast torque converter was $4K, the T/C was over $1300 of that price, but very well worth it. Also, BTS does build a great tranny.


06-25-2008, 10:17 PM
TimK...I wouldn't be embarrassed about what you paid for the ATS transmission...we too had it done to the 98 Dodge we used to have. I'll tell everyone, that upgrade cost almost $8,000, however, that included the gauge pillar and the Commander, which controlled the torque converter. It also included a double-sized input shaft, larger oil pan and heavy duty valve body.

As far as we were concerned it was the best eight grand we ever spent...YES it did shift hard, but there was no way that diesel engine was ever gonna tear up that tranny. And it never, EVER slipped.

06-26-2008, 08:38 AM
Thanks to all of you. I did take it to a shop last night to talk to them and to at least schedule a fluid flush. While I was there they pulled the dipstick to look at the fluid and his comment was that it was exceptionally good looking. Very pink..... No signs of overheating and no signs of any shavings. So..... I'm not sure what that means. He did suggest another scenario. He indicated that it was possible that it was actually the slope of the incline that I was climbing which could have caused an imbalance of some sort of the tranny fluid just at the point when it was putting the most strain on the drive train. I dunno. Sounded a little far fetched to me but I can't argue that the fluid looked great. I still plan to change it out shortly because it's almost time and we did pull strenuously for about 2600 miles. Maybe when I have it changed out they can get a better look at the fluid than just looking at the dipstick. But I guess at this point there is nothing else to do. I can only assume that what I experienced was some sort of glitch and I'll just keep my ears open for it in the future. I did get my tranny temp gauge back in working order last night so that will help. Thanks again for all the good responses. Pete

06-26-2008, 08:53 AM
Sounds like good news Pete! :) If it was a steep incline possibly it deprived the pickup fluid for a sec or two. Definitely change the filter and fluid and I suppose they will adjust the bands on the clutches. Sounds like you may be good to go!

06-27-2008, 06:41 AM
A bad seal could also be the culprit. A small leak past a seal would allow pressure to drop under load which in turn would provide less pressure to hold the discs tight resulting in slipping under load. Just had one rebuilt to the tune of 2600 dollars. They found a non-cleanup in a seal bore that came from the mfg. process. I was out of warranty but am dealing with Dodge for a reimbursement. If there was slipping, the discs are probaby already toast and the t/c cannot be cleaned so at the very least, you would be looking at a new t/c , bands and discs. Take it from an old tranny engineer, if you have burned the discs don't let them tell you they can flush the t/c and get it clean. CAN'T BE DONE!!!!!!

Hope this helps


06-27-2008, 09:25 AM
Thanks Roger. As very much a non tranny engineer let me ask you this. From what I am hearing on these posts and from others, the tranny fluid is like blood in the body. Checking the tranny fluid is like doing a blood test. It provides a very good indicator of the health of the transmission. So the question is: Can you damage a transmission under load and still have the tranny fluid look pristine??? I know that heat is the tranny's worst enemy but I'm pretty sure heat damage of any kind should leave evidence in the fluid. Thanks, Pete