Technical Oops, Dot 3 in a TH400 ?

I just bought an older, but not Hamb friendly, pickup from a guy. Truck is decent but the auto trans is bad. The seller told me that his kid put engine oil in the tranny. It still moves but barely. I've decided to do my very first rebuild of an auto trans. Confidence and Youtube will get it done.

 

I don't see why engine oil would harm an auto trans, try flushing it and refilling it with proper ATF before removing it.

But then why did he add the oil in the first place? Maybe it was out of fluid and damage was done already.

 

That may be true where you live, but remember, operations costs vary by location, even when you just consider rent and prevailing wages.

Also remember, you are paying not just for time, you are paying for the decades of experience in building complex hydro-mechanical devices, to the level that they can be operated in extreme conditions, for hundreds-of-thousands of miles, with minimal maintenance, and no call-backs. Plus, you get live, local Humans for support, when you need it.

 

we used to recycle our oil at the shop where i worked. only one big no-no!

 

Okay, it has been a while and I did put a transmission clutch pack seal in some DOT 3 brake fluid. Contrary to what I believed, it appears that the seal did swell ever so slightly and is much more pliable. It looks like it might have grown 1/16 of an inch in diameter. I wonder if the same thing would happen if I just soaked it in ATF. That's my next experiment.

 

Update... The shop went through the trans again completely. Owner put it back in and same deal. So both times they missed something...likely something simple.
So a second TH400 is taken to the shop. Same shop (not the way I would have handled things) and they got that one right. The car moved for the first time since at least '68.
Might be on the road in another year or 2...

 

Second update: Lots of summer driving around SE WI on this bad boy over the summer.
He is a happy camper

 

ive got to say ive known more than one person who put clutches and seals in a trans and called them rebuilt ! and i think there is a bit more that goes in a good remanufacture !!!

 

Quite a bit.