San Fran mechanic says, "He has never seen anything like this before."!

Two mechanics have replaced my transmission only to have it burn out during the test drive. It all started with the car refusing to shift from 3rd to 4th gear on the highway. I am stranded in San Fran until he figures it out. He is now investigating whether or not it is an electrical or computer problem. Is he missing something? Please help!

First of all, you need to tell us what kind of car we are dealing with. Year, make, model and engine size.

Tell the mechanics to check the cooler flow. A restricted transmission cooler will cook a transmission fast. Usually catastrophic failures in automatics will send trash and debris into the transmission’s radiator cooler reducing the cooling of the transmission.


I’m shocked that mechanics in San Francisco can’t handle a tranny.

You went from “two mechanics” to “he”. Oh well. Since the original thing was to REPLACE the transmission, I suppose the next step would be to replace the transmission again.

Transman, Do You Automatically (No Pun Intended) Check (Flush ?) The Cooler / Cooler Lines Whenever There’s Been A Transmission Failure, Especially A Catastrophic One ?

Or do you look for evidence of loose debris during tear down to make the decision?

Just curious and trying to learn. Thanks,


Excuose me here CSA, but don’t all shops flush the cooling system whenever the transmission is serviced or repaired.

Hey CSA,

Yes, the coolers need to be flushed any time the transmission is rebuilt/replaced. Since I am just a rebuilding shop and I am not directly involved in the R&R aspect of it my rebuilds leave my bench with two things. 1: a bottle of Lube-Gard RED already poured in the trans, and a can of cooler flush along with the warranty paperwork which clearly states that its the owners responsibility to clean and check the cooler flow prior to the transmission being placed into service. A lot of times though after a catastrophic failure or converter failure (These are nasty failures) you just cant get that trash out of the cooler and the radiator must be replaced. And yes, when I tear them down, before they go into the vat, if I see evidence of a lot of trash or evidence of a converter failure, I notate in that units file to stress upon the customer cooler replacement.


Thanks, Transman. That’s Interesting And You Run A Quality Operation.


I wonder if these hacks keep putting the same polluted/damaged converter onto the new trannies?