Can coolant leak into Auto tranny?

[Arde]

My just rebuilt E24 automatic transmission was presumably ruined by a radiator failure where coolant entered the AT fluid side of the radiator and then the transmission.

Is this at all possible? And most importantly who can I blame?!

It is my fault because the day before I thought to myself the E24 transmission was working so well I should do a paint job next. Never think to yourself, fate is listening to your thoughts and planning its ambush just to prove you wrong.

Bummed.

 

[Mike Goble]

If your tranny fluid goes through a cooler in the radiator it is possible to get coolant into your tranny, and vice versa.

 

[Arde]

If your tranny fluid goes through a cooler in the radiator it is possible to get coolant into your tranny, and vice versa.

Yes it does go through a section in the radiator.

I would think the sections would be isolated, firewalled. They can fail individually, but collectivelly is just sad.

 

[Mike Goble]

The tranny fluid is separated from the coolant by the metal wall of the tubing of the cooler. It would not be much of a cooler if there wasn't anything to pull the heat away.

 

[sfdon]

The problem can occur when the engine is shut down. The high pressure in the hydraulic system goes to zero while the coolant system goes to 1 bar. Im surprised you didn't see ATF in your coolant 1st. Let me know if you need a rebuilt 4hpeh

 

[Arde]

Happened on the highway, the coolant level light turned on and then transmission lost traction. There is no ATF in the coolant, just coolant in the transmission. Radiator did not seem to be OEM.
Getting a BEHR and rebuilding transmission again.
Don, can you PM me price and condition of that rebuilt transmission?

 

[sfdon]

What's the last 7 digits on your vin?

 

[Arde]

I am having a really hard time finding the Behr radiator to complete this repair.
I am not putting Nissens radiators again after the last one ruined my transmission.

Anybody has a line on a Behr for 87 e24 auto? part # is 17 11 1 712 448

Thanks!

 

[OCCoupe]

Radiator

Arde,
Please call Jim at mesa performance down here in costa mesa, he might have something for you. 949-642-8824

 

[Arde]

Ok, got tired of waiting for a Behrs and put another Nissens in for now.

The transmission rebuild worked great and it is smoother than ever. Plus I finally understood what Mike was saying. I thought the transmission fluid had its own pipe/fins circuit through its own section of the radiator. That ain't so, it is just a pipe immersed in one of the radiator coolant tanks, so if that pipe breaks you are toast as coolant gets into the transmission.

I also understood that this is done because what you want is not just to cool the fluid, but actually to warm it up when the engine is cold. By being a heat exchanger on the coolant it warms up faster and stays at constant temperature without using its own thermostat. Clever, except when it breaks.

Expensive education I got this time...