I have the original C4 in my 71 F100 that was rebuilt about 12 years ago. In the last few weekends after hauling some rock from the local gravel place, it's started throwing fluid from the top of the housing in what looks like an over-pressure valve. It's never done this in the 23 years I've owned it no matter how much weight I've hauled.

I've not looked in my manuals yet but thought I'd throw this out on the board if someone can shed some light on this. I tried to drive it this morning and there's no fluid on the dipstick (I let my girlfriend get the rock last weekend - BIG mistake since she drives a - hehe, Volvo).

Thanks,
BarryB

 

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What is an over pressure valve and where is it located?

 

The thing on top of the transmission is a vent. There is no such thing as on overpressure valve.

The trans was probably overheated, which expands the fluid, and then it comes out of the vent.

 

Thanks Casey. wonder why the manuals don't show this but it does make sense - interesting how after all these years it's never done this before. I check my records and it's almost 10 years to the month that I had the trans rebuilt.

This also makes sense as both times it's done this was in pretty hot weather. I'm wondering if maybe the radiator coolent paths are clogged or dirty. I might just pull the radiator and have it recored anyway. It too was replaced with a new radiator 10 years ago but I have flushed it twice, last time 3 years ago. I have 486k miles on this beast. Just ordered a new steering box - go figure it only lasted that many miles!

b

 

Excess heat comes with age.

You can install an external transmission cooler with an electric fan.