Don't make this mistake when installing a new Transmission
Flush Your Cooler Before Installing A Transmission!
This is possibly the single most important thing you need to do before an install. Things tend to accumulate in the cooler like cholesterol in your arteries. This accumulation consists of clutch material, tiny metal flakes, and oil sludge. It may not seem that this could be a large amount of material, but your cooler can hold a lot. Here’s what happens when you install a new transmission with a dirty cooler. The new fluid, with all its detergents, flows through the cooler at a higher pressure than before. This breaks loose the material, it travels through the lube circuit into the input and output shaft, through these into the planetaries and bushings, finally ends up in the pan and filter. This can damage the components as it passes through and/or it can clog the filter, restricting flow throughout the entire system.
Even though it might be a small amount of debris, and many times it is, I have seen extreme cases in my own shop years ago where a tech failed to flush a cooler, the car left, and it came back just a few days later with issues. We removed the pan and found a significant amount of debris in the pan and the filter restricted. We disassembled the transmission and cut open the torque converter, only to find that there was no source for any of the material. That’s how much can be there. It is imperative that the cooler be fully flushed and blown out or even replaced. Just blowing one out is not adequate.
There are products made just for this and should always be used when replacing a transmission. Spraying a little brake clean in there and blowing out with air is not enough. The cooler flush should be placed on each line and 1/2 of the can used in each direction. Then air should be used to blow out in each direction while watching what comes out. If you still have any debris coming out with the air once the flush is blown out, the cooler must be replaced.
I cannot stress how important this is. In my years at this I have learned that many failures and operational issues can be traced back to the cooler not being properly cleaned or replaced. Not cleaning a cooler before you install a new trans is like taking a bath in sewer water…….What’s the point?
Last edited by tbird100636; 10-05-08 at 11:22 AM.
Reason: While this is an important step, link to the other website is not, especially since it's this guys first post- link removed