Torque converter failing?

[MusPuppis]

Ok.. my second post of the night. This isnt exactly Mustang related, but this forum is extremely knowledgable and I havent found any F-150 forums that are all that helpful.

Let me do my best to explain this. I noticed it tonight while checking on a strange sound I keep hearing in my truck.

My truck has had a kind of "thud" for a while now. Its only present when taking off from a dead stop. If you've ever heard the sound anF-150 makes when the bed bolts get a little loose, thats about what it sounds like. Kinda a metallic klink but a little deeper. Anyway, while trying to source the sound tonight I had a friend looking under the truck while I would power-brake then let off. Whenever I let off from power braking I also get the sound.. and since we couldnt figure out a way to safely see under the truck when I accelerate, this seemed to fit the bill.

So, the sound is coming from the transmission, seems to be centered in the bellhousing. When I power-brake and release I get a kinda knock, the idle drops drastically and a little transmission fluid spurts out of the bellhousing. Not good. Once it even made an almost grinding sound for a second and the truck died, heh.

The truck is also sluggish from a dead stop. Its reluctant to take off worth a damn. Once I'm up to 15 or so MPH it picks up will lay you back.. but dead stop acceleration will cause a couple knocking sounds and its feels like the truck is gutless.

The truck drives extremely well in other circumstances. Cruises fine, transmission shifts pretty well, accelerates very strongly once I get going. First gear itself doesnt seem to be the problem, since its fine once I get past the initial 10-15mph.

Could this be a T/C issue or something else in the transmission?

Any info would be very helpful.

The transmission is a 4r70w in my '94 F-150. Approx. 115k on the T/C and the transmission was rebuilt about 25k or so back.

 

[bluevenom867]

Try www.f150online.com

And it sounds like a trans pump.

 

[dastang2]

you sure it is not taking off in 2nd or 3rd.

 

[BlownFiveLiter]

Try www.f150online.com

And it sounds like a trans pump.

+1

The fluid is probably coming between the hub on the torque converter and the seal where the converter mates with the pump on the trans. The biggest PITA about that is that it could be nothing to worry about, because a leak at the pump would probably have those same symptoms since you're losing pressure that the converter is building. If it's just the seal, replace it, and you may be good to go, but if there's a fair amount of wear on the converter causing the seal to leak, chances are, there's tons of metal shavings suspended in your trans fluid, and probably parts of the clutches as well. Fixing that would require a new torque converter, since you'd never be able to get all of the shavings out without grinding the welds off and physically getting inside to clean it out, and possibly a rebuild of the transmission. At the very least, it'd probably need the valve body removed and cleaned out, so you don't have blocked passages inside of it. Good luck, I hope this turns out better than it sounds. I just have a tendency to expect the worst from my personal experiences.

 

[MusPuppis]

Im sure its taking off in first gear.

Thanks for the info. Yeah, if its going, oh well. I think I have a line on a free T/C and I can rebuild the tranny if it comes to that. Which is probably will.

I'll just drive it till it flops, then fix what needs fixin.

 

[rd]

If you are sure it is a 4r70W, there are some good places to check. F150 online is one, as someone said.

The torque converter has been an issue with at least the later ones. My 97 F150 had torque conveter shudder, but a fluid upgrade from Mercon 3 to Mercon 5 fixed it.

Sounds like you have a converter problem, a pump problem or the end play has become excessive. It could be just a thrust washer failure. But it probably has to come out.

 

[Black1987Stang]

I say its the torque coverter, or maybe a bad seal related to the torque converter, does it do it in manual 1st gear? or only Drive?