Dish detergent to clean oil sludge out of the cooling system?

Can anyone tell me if they have ever heard of/done this?

We have a truck at work that had oil leaking into the coolant system, apparently from the oil cooler core. What happened is the oil seeped in, and when mixed with the coolant, congealed into a gooey, slimy grey mess that clogged up the system, cause it to overheat, and finally blow a hose.

Anyway, our mechanic has replaced the oil cooler, and filled the cooling system with water and Dawn dishwashing liquid. What he wants me to do, is drive the hell out of her and get her good and hot, and then drain the system and repeat with the Dawn and water. He says it will clean all the gunk out of the system, at which point the truck will get fresh coolant and go back into normal service.

Logic tells me that dishwashing liquid will break up a sludgy buildup and clean the system out, but I have never heard of anyone doing this with a cooling system, and neither has any other driver that I work with, so the alarms are going off in my head right now. I went so far as to talk with my boss and get assurances from him that I would not beheld responsible in the event of a catastrophic failure. Still, I have absolutely zero desire to run the risk of blowing up a very reliable tractor. Especially one that I love to drive every day.

Has anyone ever heard of this? Is it safe?

Like I said, logic tells me it is, but I'm still not 100% on board with it. Thanks in advance.

 

He wants me to take her out on a 160 mi. r/t run that I make just about every day. I'll be running her 75mph for a couple of 20+mi. legs while carrying 7000gal. of fuel in the trailer.

Did you run yours under load also?

Would it make any difference?

How may times did you flush the system with the soap/water mix before you loaded coolant?

 

Cool. Thank You so much. I have a fair amount of experince wrenching on my own vehicles, but I'm new to the driving tractor-trailers, and obviously not an expert on diesel technology. I really appreciate the input.

 

Duly noted. I will tell him to put new hardware in case he hasn't already. Thank you.

 

I think he said he was using dawn, but whip knows?