I recently had a transmission failure and have flushed the trans coolers and lines with three cans of Kooler Kleen. Ran the second and third cans into a clean jug to see what's coming out. Even after the third can the fluid is gray and can still see black specs coming out. Although better then the second it still doesn't run perfectly clean after three cans. The Kooler Kleen is 11 dollars a can, so how many do I put through it? The can says half the can one direction and the other half the opposite. I'm not satisfied with the way it looks yet!

 

I do have a trucool which I've heard in the past is hard to flush. The transmission had a clutch and converter failure. No hard parts.

 

At 3 cans & possibly more, u are almost 1/3 the cost of a new cooler. Just a thought.
While it may not be necessary, u can virtually guarantee it isn't contaminated (if new).
And I know $110 or so, whatever they run nowadays, is a small price to pay in regards to your total build of your truck.

It may be worth it if it clears your mind & removes any doubt. But, I don't wanna spend your $ for u.

Also, u said u heard they're hard to flush. As an aside, do u know those bits or gray aren't from inside tranny or pan vs lines & cooler?
Just tryin to rule all variables out.

 

Tom has a valid point, something to consider. Personally I wouldn't be happy till it came out clean and who knows how much that will take.

 

GM replaces the cooler in some cases like this.

If you can't get it clean, I would recommend it.

Cooler cleaner is designed to be safe with transmissions just in case any residual is left in the lines. Other solvents like brake clean are not recommended as the can be harsh on the clutches and cause damage.

I sometimes use the Cheapest trans fluid I can find to flush the lines first. When it comes out clean, then I use the cooler clean.

 

In the old days we used mineral spirits in a barrel with a pump to clean the lines. The issue is that debris/sludge still sticks in there. These days we use a heated hot flush machine that uses atf. This pumps at high pressure and also every so often it will stop pumping and then blast the lines with air. This machine allows us to be able to inspect what is coming out of the lines/cooler and also reverse it easily. When its clean we are done. With what you are doing I would blow air through the lines in between pushing the CC. Do this before you even start in both directions and blow it into a jug. Then do this again while using the cooler cleaner. Obviously not while pushing the solvent through the lines!

 

What about using a GM trans cooler flush machine? Sounds about like the same machine you are talking about. The machine doesn't have any adapters for AN lines like I have though. Probably can cobble something together though.

 

use a heated pulsing flush machine... swap flow directions and VERIFY VISUALLY that nothing is coming out.

If its a bad enough failure though, I'd just blow the lines out and replace the cooler. Those plate/fin coolers have nooks and corners that will catch crap regardless of what kind of flusher you use...

 

So I can easily replace the trucool but what about the cooler in the radiator?

 

You can bypass the radiator, its actually a heater to warm up fluid during cold climates I believe.