Fluid out the Vent


New Member
May 25, 2001
I've been having problems with my tranny for a little while now and been asking for suggestions. I got another little piece of data yesterday on the highway coming home from work. Doing about 75-80, rpm's in OD were about 4000 (this is an Art Carr non-L/U tranny with 3500 stall converter). Does this RPM seem right or is that a 3rd gear rpm?? Hard to tell what gear it was in by counting the shifts. But after a couple miles of this I started getting a cloud of smoke behind me and a strong tranny fluid smell. I've been having a tranny fluid smell occassionally before, but could never find any leakage. Well, this time I found it. It's coming from the vent tube in the top of the tranny. Any ideas what would cause this? The tranny fluid level is good, but does have a burnt smell to it I think. I've had the pan off with NO abnormal material in it. I'm running the new Ford tranny fluid FA. Does this have more of a burnt smell to it new? (didn't smell it before I put it in) I still have Reverse slipping pretty badly MOST of the time. Sometimes it will work decent though. The forward gears and shifts seem to work good. Only problems are the fluid from the vent, burnt smell, and slipping reverse now. This all started when I put in a stageright T-Brake. It is out now, and that helped the reverse problem, but still have these things happening. I'm at my witts end, and I can't afford a new tranny until tax refund time.
Anyone have experience with the switch pitch TH-400 tranny? I'm seriously considering switching over since I'm in Hawaii and there aren't too many highways here (3 to be exact) so I don't do much highway driving.

Thanks for any help or suggestions.

87GN 11.8@118mph (BEFORE 3/4 of the below mods)
Bad news.

Before I even got to the part where you mentioned a burned smell, I was thinking that you are overheating your transmission. Your comment confirms my suspicion.

Without the benefit of the lock-up, the additional load created by overdrive (equivalent of running a 3500-stall conv. w/ a 2.29 rear gear) translates to slip which is heat.

If you can't afford a trans. overhaul at this time, I'd recommend a fluid change, high-capacity, supplemental trans-cooler and a temperature gauge.

You may also find that by cruising in Drive instead of OD, you'll build less heat in the system.

Lastly, reverse slippage is either due to the low/reverse clutches slipping and/or the direct clutches slipping. If your direct clutches are slipping, you may also be experiencing slip in third and fourth gears as well. If that's the case, you soon may have no choice about getting an overhaul.
I have Two external Tranny coolers actually. I planned today to remove a cooler line and make sure there is flow and no obstructions in the lines. By any chance do you know which port on the tranny is the outlet to the cooler? This way I can selectively choose where to break the line and check the entire cooler system vice having to break the lines twice to check the flow.

The top fitting is cooler feed, bottom is return. Good thinking to verify flow.