So as some of you know I was driving home Saturday when and I started losing Tranny fluid fast as I was going down the highway. It started pouring out the bottom of the bell housing. I am wondering what to look for as far as what failed. Should I just pull my tranny now, If so what am I looking for, a bad seal? I need help trannys are my weak point knowledge wise. I was cruising up the mountain pass at bout 85 MPH when it started leaking got another 10 or 15 miles before it was done and left me stranded. Nothing funny heard or felt when it occurred. Thanks Dan

 

hmmm 85 mph? sounds like a front tranny seal, my first guess, especially with the symptoms of being able to drive with a trail of fluid.

quick and easy fix, however check the TQ for scoring on the shaft. FYI a decent shop can have it done in about 4 hours real time. I could do it in a day with a floor jack and lousy tools.

 

The seals on my converter went a few years ago... sounds similar to what you're describing

 

O.K., so Im gonna drop the trans. I have enough tools to do this. Next is when you guys say seal, is it similar to the rear output shaft seal? Or is it a seal on or in the TQ? If i dont know what im looking at should I consider a new TQ or is this just throwing money at guessing the problem?

 

I didn't do the repair, local shop did. He explained it just as i said lol. So basically no help from me lol... my fault Dan

 

pretty much same as rear seal, except smaller and doesn't have a stop flange. Goes on same way. there might be visible grooving on TQ shaft BUT unless your fingernail gets hung up in the edge of the groove, it won't necessarily be a problem. if you have a micrometer, the gasket will compensate for .001 TQ shaft difference. you can also put the seal in farther or shallower if needed.

otherwise just put it on in about the same depth as the old one. I grease mine with a dab of vaseline then carefully put it back together.

careful, the tranny is heavy, curse ing and beer are optional, as required

 

I love it, R&R two trannys in the last twelve months on my 60 F100 and Im there, beer fridge stocked along with parts, tool, etc.
I have always used Lithium Lube in the past should be bout the same as vasoline heh?

 

Yeah but the vaseline has other uses......

 

Ha Ha , Got it , I better grab a jar for the tool box.

Another dumb question. I checked the Tranny fluid level before I made the trip and I was half a quart low, I dumped in a quart. Could I have overfilled and caused the seal to blow out?

 

Yes you could. If the trans is overfilled, though I don't think a half quart over would do it it, the rotating parts will whip the fluid into a foam, and that also causes quite a bit of heat. Foamed fluid does not transmit pressure well, so this could also have made the torque converter clutch slip, which would create A LOT more heat.

 

Mark, could you comment on whether it would have been better if Dan had run a half-quart low rather than a half-quart over with the 4R100 tranny in particular and automatics in general. I've always, if I had to, run the tranny a little low rather than too full.

 

When you say quite a bit of heat, the trans temp reading was normal for my rig (180 degrees ) untill I started losing fluid and the sending unit had nothing to read. My question is if I consistently run at a certain temp ( in my case 180) is that normal?

 

I think running a bit low is less bad than running a bit overfilled in most cases.

Running at 180F is normal. It is possible that the torque converter was slipping. That will create a lot of heat at the converter, but the cooler would be able to cool the fluid before it got back to the trans, especially if the truck wasn't fully loaded or towing.

 

Mark, when you say the torque converter may have been slipping is there a bench test for the TQ when I get the tranny pulled? Also could this have all been prevented had I had a larger Trans Cooler?
Thanks Dan

 

There's no bench test that I'm aware of. You can examine the torque converter. If the cover is blued, it's been badly overheated.

A larger trans cooler might have prevented this.