Atf in coolant system

[Jwinter]

Good evening everybody, I recently purchased an '89 W350 dump truck with 81000 original miles. Truck has 727 trans. Last year previous owner blew transmission and parked the truck. I noticed ATF in coolant when I looked at truck, the price was cheap and I've been looking for one to buy for years so I pulled the trigger. Were having the trans rebuilt this week. My question is, could trans failure cause this or would the culprit be the cooler on side of block? Should I buy another cooler?

I'm super excited about the truck and glad I found TDR!! Any advice much appreciated.

 

[Shadrach]

Welcome aboard. At least get the trans cooler pressure tested. To flush the block use a good quality laundry detergent like Arm & Hammer. It cuts thru oil and grease. Rinse the rad out real good until the coolant comes out clean. Then fill with fresh antifreeze. David

 

[Bob Beauchaine]

First of all welcome aboard the TDR



Your problem could be the trans cooler located under the exhaust manifold. It's where the trans fluid is is cooled by the coolant. If there is a leak in the trans fluid lines it will mix with the coolant. That is where I would look for your problem.



Bob

 

[DVolk]

From tons of exsperience on transmission going south , dont re use the cooler either get it a replacement or a aftermarket one , with all of the small vanes they never get clean , also make shure a new converter is used as well .
It is also strongly advised for the first 1000 miles or so to run a inline oil filter on the cooler lines .

 

[cerberusiam]

The mixing problem is in the heat exchanger under the exhaust manifold, typical failure after many years. As much abuse as they take it is a wonder they last as long as they do. With a non-lockup transmission the heat exchanger is almost mandatory. It is close to impossible to cool the trans fluid without extensive mods without it. The efficacy of the heat exchanger is so much higher than an air to fluid cooler it is hard to replace it.

 

[Jwinter]

Thanks a lot guys! Got the transmission out today. Also noticed that I need a flex plate. Guess ill order one for a 2nd gen from cummins. Looking for a good used cooler, can't wait to start using the truck.

 

[DVolk]

What do you use to remove the heat exchanger set up as i got a engine im puting a manual behind it

 

[cerberusiam]

The heat excahnger just unbolts from the block. You can either block off the coolant ports or run a hose between them.

 

[DVolk]

OK fair enouth , are the ports pipe thread ? , this is on a 94 block

 

[cerberusiam]

I think it is still NPT on a 94, that is before the STORM block so it should good old pipe thread. Unless it was cast in England then it may be British Pipe thread. LOL!