Advice needed on a bad chain of Auto events



I bought a used Chevy 1500 Silverado and the 4th or 5th time I drove it, the transmission went completely out. I then took it to a local Tranny rebuild shop and had it rebuilt for $1900.00 !!!

I left the rebuild shop and in less than 15 miles, while trying to pass a car doing 45-50 mph, the tranny dove down to what seemed to be 1st gear and stayed… it overheated almost immediately and blew a cooling hose off. The temperature sky-rocketed so I parked it and called the shop. They came to get it. I pulled the radiator cap to find brownish sludge in my radiator !!! Now the hoses are all real soft and limp feeling and it doesn’t seem like the thermostat is cycling water at all. It used to run about 200 degrees then drop to 170… now it never gets over 110 ??? I am worried, and I wonder if the tranny repairman is at fault for this damage to my cooling system ??? I have had it back to him 2 more times and it still is shifting weird while I apply more than 3/4 throttle to the tranny. Just want to know what ground I stand on. Many thanks in advance.


I have a feeling that when your truck got too hot, the thermostat spring weakened and now its stuck open. Time to flush that cooling system and replace the thermostat.

Additionally, there’s the possibility that you have a leaking transmission core in your radiator, hopefully that is not the case. Monitor your transmission fluid level and color. If you have any indication that transmission fluid is making it in to the cooling system, or vice versa, you’ve got a problem that needs to be taken care of immediately.


Maybe the transmission fluid cooler that is inside the radiator is rotted out and this was the cause of the first trans failure.
If this was not inspected and repaired when the trans was rebuilt then it’s no doubt the cause of the latest trans failure.

You stated the trans dropped into first gear and it overheated almost immediately. How immediately?
Did you continue driving the truck at higher RPMS and if so, how far?

It could possibly be a thermostat failure and the brownish sludge in the radiator is probably going to be either transmission fluid or sludged up DexCool coolant; or both.
You might consider taking a look at the trans fluid and not only making sure the level is full, but also that the fluid is clean and not discolored.

You should also keep in mind that just like an engine, there are a number of ways to rebuild a transmission; soft parts, soft and hard parts, any updates, etc.
Some ways are much better than others and a lot depends on the guy doing it.


Given you likely have no idea of history you cannot lay any blame on any party except possibly yourself if it was not checked over by a mechanic prior to purchase.

You just purchased the truck how can correlate a likely previous problem on the 6th time to anything?

Good luck, I hope all comes out in the wash.


Thanks for the info, I will replace the radiator, all hoses and thermostat and then go from there.

As far as the reply from the other guy suggesting I caused the problem, I had the fluids all changed and I had no problems for a couple weeks after buying it. The trouble started when the transmission automatically down-shifted to 1st gear while I was doing 55 mph… I pulled over ASAP but it was already boiling by that time. You figure it out… I know enough to know the coolant was spotless until the tranny rebuild… anyway, I will keep flushing the cooling system until it runs good and clean, then start replacing parts. Thanks for the replies thus far



model year, engine, mileage?