Transmission oil cooler questions

[Honeydipped]

Hey Folks!


So the last few weekends I've been crawling under my bus, getting to know it a little better, checking for potential problems, and remediating rust spots. I haven't touched my interior since I've gotten it (other than removing the seats) and probably won't until next year once I'm happy with how the undercarriage and motor looks.

I've found a couple of hydraulic hoses that needs replaced soon-ish, but my major concern is my transmission oil heat exchanger - it is a rusted disaster. It's so bad I'm seeing green liquid (i.e. coolant) seeping through the edges where it's rusted bad.

SO.. I bought one.. but it isn't a factory replacement. It is similar as it is also a Rocore shell and tube cooler, but it is a bit beefier (it came from a MCI D4500 that was being parted out..)

I believe the oil port is SAE #20, and coolant lines are self explanatory, but I had a couple questions on some items that I circled (see below).


First (circled in red), it appears there is a T on one of the oil ports where the transmission oil would go into one side, but there is bushing and then a much smaller fitting screwed into the bushing that I have no idea what this was originally for. Any ideas what this was used for and if it would be safe to remove the bushing and cap that end of the T?

Second (circled in blue) there are two small ports on the end cap of this heat exchanger, on the opposite side of the coolant ports. One has been capped off via a screwed insert, the second is open. Any idea what these are for and if it would be ok to cap these off as well?

For my current setup, which is rusted to ****, it is just one coolant line in and one out, one transmission line in, and one out. I'd like to keep it simple like that, but I'm unsure on what these other two ports/fittings are for in this new heat exchanger. Any ideas? If it helps, my transmission is an Allison MD3066(R) and the new heat exchanger is a Rocore 5-7041b (https://www.rocore.com/phocadownload/rocore-shell-tube-catalog.pdf).

 

[Honeydipped]

After talking with a Rocore rep the ports circled in blue are for draining or de-aeration. He said:
“The (2) small ports on the “return” end of the cooler can be used to either drain coolant, or used for a dearation line for the coolant circuit.

The ports take 0.25-inch pipe plugs. These ports are not usually used, as EGW is now used, instead of water. And, the cooler normally dearates naturally when mounted horizontally.”

So that clears that up. Still no idea what the fitting circled in red was originally supposed to do. I think I’ll just cap it off and go from there.

 

[bus-bro]

That thing at the end of the T might be for bleeding air out of the oil side of the cooler. Might be useful.

 

[Bus'n it]

The small fitting circled in red is for a 1/4" air line tubing that goes to your coolant surge tank. It helps bleed out air from the cooler.

 

[magnakansas]

disagree

blue areas I think are for coolant ports..... the one in red is for oil.... it is a bleed valve for helping air out of the oil lines.....

william

 

[Honeydipped]

I do like the idea of purging air out of the transmission oil loop. That’s one thing I was worried about for when I install this. Thanks everyone for the feedback!