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CLKimmel · 11-03-2022, 05:25 PM

Hi folks
Today as I was parking the coach, I noticed I was leaking something. After a quick look, I see that a hose must have given up the struggle. The hose comes out of the transmission and goes into a box of some sort that seems to also have coolant hoses connected. Can anyone identify this box?

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The red circles are the hydraulic hoses that connect to the transmission and one is leaking. The yellow is the thing I don’t know what it is. I plan on changing both hoses just not sure what this is.

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Old Scout · 11-03-2022, 05:32 PM

It's the cooler for the tranny--rather than the more traditional set-up of having the tranny cooler imbedded in the bottom of the radiator, some RV builders use a remote cooler where tranny fluid is circulated thru a box where engine coolant is routed. So smaller hoses in your pic are from/to the tranny.

code2e · 11-03-2022, 05:40 PM

The box is your transmission cooler. It is a heat exchanger type. The transmission fluid is pumped thru a cooler inside the box. Engine coolant is pumped through the box around and thru the cooler fins. Dual purpose, warms transmission oil faster on startup and removes excess heat when transmission runs warmer than coolant.

Your cooler and the trans hose fittings are very corroded. I would soak them with PB Blaster a few times before trying to disassemble. Be sure to use backup wrench to not transfer force to cooler fitting. Cooler may be a future problem if it rusts thru. Likely coolant leak.

CLKimmel · 11-03-2022, 05:57 PM

Thanks, I’ve already sprayed with pb blaster and will again a couple of times before I try to remove the hoses. I am concerned about the corrosion and I expect I’ll be replacing the cooler eventually. Any idea where to get one?

code2e · 11-03-2022, 06:14 PM

Quote:

Originally Posted by CLKimmel

Thanks, I’ve already sprayed with pb blaster and will again a couple of times before I try to remove the hoses. I am concerned about the corrosion and I expect I’ll be replacing the cooler eventually. Any idea where to get one?

If you have an Allison transmission, it might be worth checking with an Allison dealer. Allison might have provided the original part.

A few years ago, I worked a summer job at a larger radiator shop, Mac's Radiator with several locations in Oregon. They were very resourceful in finding coolers and intercoolers for folks. May be worth checking with a shop near you.

Dutch Star Don · 11-03-2022, 08:36 PM

That same cooler is still used on new models. My 2005 Diplomat on a Roadmaster chassis and my 2014 and 2019 Dutch Star on a Freightliner chassis all used that cooler. You should be able to find one fairly easy.

Warning......In 2019 and probably into 2020, those transmission coolers had an issue with the welded bungs on the top leaking. Mine leaked and was replaced by Freightliner under warranty. Our friends 2019 Allegro Bus also leaked and was replaced by Tiffin. I believe they were taking the new leaking ones off and repairing them as it was just a leak in the weld. You may find one at a repair shop that just needs to be rewelded at the leak.

CLKimmel · 11-14-2022, 05:13 PM

Progress! Yesterday, with the help of my neighbor, we got the hoses removed. I never would have been able to do it myself. It took big wrenches, lots of heat, muscle and a pipe to get one of the hose fittings separated from the transmission fitting and we had to cut the hoses and use an impact to break the other one free. Now I need to get new ones made and re-installed. I’ve got new transsynd and filters on the way so I can change them after the hoses are replaced.