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Cummins 6BTA Coolant Flush

Posted: September 30th, 2025, 8:20 pm
by 650Guy
I'm looking to flush and fill the coolant on my cummins engines. Having never done it, i'm looking for some guidance. Last time I did this was in my 1979 Pinto and I was able to install an inline T that allowed me to flush fresh water through the block.

Has anyone figured out a way to do that in the 6BT engines? man that would be a big help!

Re: Cummins 6BTA Coolant Flush

Posted: October 2nd, 2025, 3:34 pm
by KyleR
Not sure about the T-fitting idea, but I've drained/refilled the coolant on both my 6BTA engines and it's not terrible. The main thing is to refill very slowly. I did it per the manual which is available free online at the following link. You just have to register and then once you login you can enter your engine serial number(s) and have access to all manuals including the operator's manual and the service manual.

https://quickserve.cummins.com/info/index.html

Attached is a pic of the drain location.

Kyle

Re: Cummins 6BTA Coolant Flush

Posted: October 2nd, 2025, 5:38 pm
by 650Guy
Thank you!!!

Did you just swap it with the old green stuff or did you convert to the newer red? From what I read the red last longer but I have to do a complete flush to switch.

Re: Cummins 6BTA Coolant Flush

Posted: October 2nd, 2025, 6:28 pm
by KyleR
I went down the coolant rabbit-hole and here's what I ended up using. It specifically names Cummins diesel engines on the back of the container (I circled it in red). It's given me no problems and I've been happy with it.

The only difference from my pics is that I ended up using concentrated version as it was significantly cheaper to buy it and then get a few gallons of DI water for dilution. From what I remember each engine including the HX holds almost 6gallons.

Kyle

Re: Cummins 6BTA Coolant Flush

Posted: October 3rd, 2025, 1:09 pm
by 650Guy
awesome! thank you!!! this seems like a much simpler route than flushing the block with a nutralizing solution, then replacing the coolant with the new high tech long lasting stuff.