I took my 302 91 Ford Bronco, automatic, out on the highway for the first time since I have owned it. Planned on taking a 3 hour trip but about 10 minutes into the trip one of the passengers smelled something burning. I ignored it and continued on for about an hour and 15 minutes when I noticed smoke coming from underneath the car. I pulled off at the next exit and checked the underside of the truck to find it covered in transmission fluid. The smoke was the trans fluid hitting the exhaust and burning up. I checked the trans fluid level and found that it was full - actually overfilled. I haven't filled the trans fluid since I owned it (bought in February). I figured the fluid was full so I would try and make it home. I made it home with no problems - as a matter of fact, no more burning smell or smoke. When I stopped at the exit light and began to accelerate the truck bogged down like it was going to stall. Under very light acceleration it would smoothly accelerate and shift but upon heavier acceleration it would bog down again. I made it to the mechanic who looked at the truck and said he couldn't find anything wrong with it and that it was probably that the heat and pressure built up in the tranny causing the fluid to come out the dipstick. He said the bogging down could have been the fact that the heat in the tranny built up so much that there was some slippage or something. I am not really sure about all this. The truck drives fine now although I haven't tried it on the highway again. What do you all think?
My other question is a result of me changing the tranny fluid this weekend. I figured since all this happened I should probably change the fluid and filter. In my other car the trans fluid filter just pushed into place - is this the same on these transmissions. I pushed it as far in as it would go and called it a day - is this correct? I would hate to have it fall out and screw up the transmission - if it isn't screwed already!
Thanks for all your replies - I am anxious to hear what the real experts have to say!

Thanks and enjoy the rest of the weekend

 

What transmission is in your Bronco ? There are a lot of places leaks can occur , Can you identify where the leak is / was coming from ? The fill tube , speedometer cable , vent tube , trans cooler lines etc .

 

Paul.

Will overfilling an AOD cause it to overflow/leak from the vent tube when driving? What problems can overfilling cause?

Thanks in advance, Marty.

1992 F150 Supercab SB 4x4 302 AOD 3.55 31x10.5 All Terrain on Ford 15x8 Ralleys

 

Marty , Yes , Atf Expands as it warms . Thats why there is a cold & warm marks on the trans dipstick . Drain & refils should only be topped off to the full cold mark . Drive the vehicle until the trans is fully warmed & recheck the fluid level . It should be at the full warm mark .

 

Also in a "badly" overheated automatic transmission the fluid will expand to the point of puking it out where ever it can find a place to relieve the pressure and increased volume, be it a seal, or the vent tube, or if everything else holds, the dip stick tube. I've seen auto transmissions be so hot they would be showing way overfull on the dip stick and 3 hrs later(sitting to cool off) be a little low( of course using the proper method of checking). The fluid and filter change is a good place to start anyway. Maybe a stopped up trans filter causing it to heat up.

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver