Seeking help diagnosing C6 Trans
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Seeking help diagnosing C6 Trans
1988 F250 XLT Lariet, 460, C6, 4x4, reg cab, long bed.
My transmission started leaking last year after a road trip with a slide-in camper. Prior to this trip with the camper there was no leak.
I diagnosed the leak as a failed input shaft seal. I dropped the transmission and replaced the seal, and no more leaking. I then resumed driving the truck for several weeks as a daily driver. And no leaking.
Last weekend I put the camper back on the truck and went ice-fishing / camping. The round trip was about 200 miles highway. While returning home I got into the city and while stopped at a traffic light I could smell what I knew was trans fluid dripping on the exhaust pipe. I got home and could see the fluid leaking from the inspection plate on the bell housing.
So twice now, both times with the camper on and a highway trip, I get this leak. I'm wondering if it's a "failed" seal, or is the trans being overworked, and the seal pushed beyond its capacity?
The transmission shifts perfectly near as I can tell. The truck doesn't seem to break a sweat hauling the camper, plus small trailer, plus snowmobile.
My transmission started leaking last year after a road trip with a slide-in camper. Prior to this trip with the camper there was no leak.
I diagnosed the leak as a failed input shaft seal. I dropped the transmission and replaced the seal, and no more leaking. I then resumed driving the truck for several weeks as a daily driver. And no leaking.
Last weekend I put the camper back on the truck and went ice-fishing / camping. The round trip was about 200 miles highway. While returning home I got into the city and while stopped at a traffic light I could smell what I knew was trans fluid dripping on the exhaust pipe. I got home and could see the fluid leaking from the inspection plate on the bell housing.
So twice now, both times with the camper on and a highway trip, I get this leak. I'm wondering if it's a "failed" seal, or is the trans being overworked, and the seal pushed beyond its capacity?
The transmission shifts perfectly near as I can tell. The truck doesn't seem to break a sweat hauling the camper, plus small trailer, plus snowmobile.
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From: Central Indiana
Just my $0.02 USD worth
Some thoughts.
Condition of torque converter snout. If there's a groove worn into it by the seal, the leak will keep coming back every time you work the trans hard at freeway speeds.
Condition of the bushing that supports the snout of the converter. If that bushing is worn out, you never stop the leak. Needs a new bushing in the pump. If you have a bunch of miles on the trans, it well may need replacing. A good trans shop would not replace just the seal, no matter how bad the fluid was puking out. They would do the bushing, too.
Condition of torque converter snout. If there's a groove worn into it by the seal, the leak will keep coming back every time you work the trans hard at freeway speeds.
Condition of the bushing that supports the snout of the converter. If that bushing is worn out, you never stop the leak. Needs a new bushing in the pump. If you have a bunch of miles on the trans, it well may need replacing. A good trans shop would not replace just the seal, no matter how bad the fluid was puking out. They would do the bushing, too.
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Thanks for the input. The torque converter snout looked in good shape. Might well be the bushing you described.
I sure thought I had it beat the first time because the seal change stopped the leak. But with the camper on there, putting a meaningful load on it, it leaks.
I sure thought I had it beat the first time because the seal change stopped the leak. But with the camper on there, putting a meaningful load on it, it leaks.
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Joined: Aug 2010
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From: Chillicothe
Also, the c6 hasn't been a factory installed transmission for a long time. Much of the stock at parts stores and the warehouses that support them is a decade old.
I ran into this problem about ten years ago when rebuilding a 370 for my old man's dumo truck. Used Fel-pro gaskets and had a rear main leak when warmed up. I went back to the parts house and they exchanged it, same problem was fine till warmed up.
Well, that weekend I had a race parts convention in Shaumburg, Illinois. I ran in to the Fel-pro Rep and told him what was going on. And even gave him the part number of the seal. He asked for my email and said he would get back to me. I figured he was just blowing me off, but Monday I had an email asking for my address, he had something to send me.
Two days later the high dollar Viton rear seal showed up, with a letter stating that the 385 series has been out of production so long the seals in kits have shrunk. And that I should order from Summit or Kegs if I need seals that have to hold pressurized fluids.
I ran into this problem about ten years ago when rebuilding a 370 for my old man's dumo truck. Used Fel-pro gaskets and had a rear main leak when warmed up. I went back to the parts house and they exchanged it, same problem was fine till warmed up.
Well, that weekend I had a race parts convention in Shaumburg, Illinois. I ran in to the Fel-pro Rep and told him what was going on. And even gave him the part number of the seal. He asked for my email and said he would get back to me. I figured he was just blowing me off, but Monday I had an email asking for my address, he had something to send me.
Two days later the high dollar Viton rear seal showed up, with a letter stating that the 385 series has been out of production so long the seals in kits have shrunk. And that I should order from Summit or Kegs if I need seals that have to hold pressurized fluids.
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In the interest of "simplest solution first" I'll start with a better quality seal and see if that fixes the problem. I ordered the RACER X high performance seal as described above. Not sure when I'll have the time to do the work, but I'll post results when I have something to report.
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Update: I'm sure everyone has been holding their breath waiting to know how this turned out.
I did order the "Racer X" high performance seal. It did have a slightly different design than the one it replaced. Yesterday I dropped the transmission and installed the seal. Re-installed the transmission this morning. And after additional reading on cooling an automatic transmission I also replaced the Ford aux cooler. The Ford cooler is a plate-style cooler
about 11" x 6".
I replaced the original one with a 11" x 9" plate-style aftermarket cooler, plus an additional 11" x 9" twin. So now I'm set up with a total of 11" x 18" of cooling. Tomorrow I'm putting the camper back on and hitting the road for the same road trip that resulted in the leak which inspired this thread. I'll make the road trip and keep and eye on the leak issue and let everyone know how it goes.
* Also - raystankewitz
I checked the snout of the torque converter when I had it off. It looked fine and felt smooth as silk. I could see minor variations in the surface finish but they were undetectable by touch / fingertip.
I did order the "Racer X" high performance seal. It did have a slightly different design than the one it replaced. Yesterday I dropped the transmission and installed the seal. Re-installed the transmission this morning. And after additional reading on cooling an automatic transmission I also replaced the Ford aux cooler. The Ford cooler is a plate-style cooler
about 11" x 6".
I replaced the original one with a 11" x 9" plate-style aftermarket cooler, plus an additional 11" x 9" twin. So now I'm set up with a total of 11" x 18" of cooling. Tomorrow I'm putting the camper back on and hitting the road for the same road trip that resulted in the leak which inspired this thread. I'll make the road trip and keep and eye on the leak issue and let everyone know how it goes.
* Also - raystankewitz
I checked the snout of the torque converter when I had it off. It looked fine and felt smooth as silk. I could see minor variations in the surface finish but they were undetectable by touch / fingertip.
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I just got back from the trip and the results are in...No more leaking!
Of course I realize there was a flaw in my approach to this in that I applied two possible remedies simultaneously. Which one was the actual solution, the "high performance" seal? Or the new coolers? Or the combination of the two? I don't actually care. I'm just thrilled that the problem is resolved.
Of course I realize there was a flaw in my approach to this in that I applied two possible remedies simultaneously. Which one was the actual solution, the "high performance" seal? Or the new coolers? Or the combination of the two? I don't actually care. I'm just thrilled that the problem is resolved.
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