Adding an auxillary radiator - RE3000 1998 T444E MD3060

[RobertTheSwede]

Hi all!

Summary: I've just added an auxiliary radiator to my bus to combat overheating issues. Stand by for updates.

This site has been a wonderful source of information during our bus conversion and first time living full time on the road.
I therefore wanted to give something back and so Im creating this thread to share my experience adding an auxiliary radiator.

Tech specs:
1998 international Re3000 (rear engine) with 200k+ miles on it.
T444E 7.3L diesel V8 with an Allison MD3060 (remanufactured a few months back).
Pulling a jeep wrangler, flat tow.
100 gallons diesel
220 gallons fresh water
110 gallons Grey water
This thing is probably closer to 30k lbs, and yes we have class B exempt drivers licenses.

We've been experiencing overheating issues with it since a long time.
Going straight forward above 50mph on flat highway it will exceed 220f within 20 minutes.
If it's hot outside (80f+) it will exceed 230f.
Going uphill it will go above 240 unless we keep it in second gear with lockup engaged. And even then we have to stop every now and then to let it cool down.

I've replaced the water pump.
Removed and cleaned the intercooler (which was filthy! Who's idea was it to have the crankcase ventilation hose exit right in front of the fan that pushes air through the radiators and out? It is moved now...).
The oil side of the radiator was flushed when the new transmission was put it.
The waterside has been flushed and chemically flushed by international workshop.
I've added extra electric fans on the outside of the radiator to help pull air through it at low speeds.

All of the above has helped, especially the intercooler being clogged (back then it would instantly overheat no matter what which is why I disassembled the unit to start with), but even though they all improved performance it still isn't enough.

The in and out temperatures across the radiator never exceed 20f, so it's not a question of restricted flow through it.
I have, however, identified a coldspot on the radiator.
The leftmost (driver) side, when running hot (220+) will have a temperature drop of over 30f in a small area that is not symmetric to the other side.
It is possible one of the vertical coolant carrying tube's through the radiator is clogged despite the flushes.
Because it's such a small area that's cold I doubt it degrades performance enough to be solely to blame for the over heating issues.

Now, if it wasn't for the fact that I've made the radiator much more difficult to get out I may have considered replacing it with a new one, but I don't want to open the transmission circuit since it's under warranty and a new one is quite expensive (1200+ usd).

Therefore I've now added an auxiliary radiator on the driver side inside the engine bay.
The radiator has replaced the floor that used to be there (I assume for air flow management or for keeping debree out of the engine area, if anybody knows do let me know).
See attached pictures now.
I cut away the floor that wasn't immediately above the exhaust pipe and then built small mounts for the radiator to rest on.

The old aux heater waterpump was still attached to the wall but disconnected. We also have no water flowing to the front of the bus, those hoses were disconnected and removed (partially) by precious owner.
We have a minisplit setup that give us hot or cold air in the front so we don't need it anyways.
Therefor I repurposed that waterpump to be our auxiliary cooling pump instead.
After the pump I routed hoses to the cooler and back to the return hose.
The power that feeds the pump (toggled by a button at the driver) now also powers the relay for power to the electric fan on top of the new radiator.
It's a fan that is reversible and I've set it to push air down through the radiator and out through the floor.
I hope this will help to such air in through the side scoops and into the engine bay while ejecting the hot air down and out. Allowing for more cold air to go through the main radiator instead of heating up the air inside the engine bay even more.

I don't expect this solution to make a world of a difference but it may be just enough to get us back within a reasonable range of temperatures given a reasonable driving pace. (Still never going to keep up with anything else on the roads though ofcourse).

The radiator and fan were punched at NAPA (only shop in town out here). Details:

RADIATOR
NRC NR 2767A
141.99

ELECTRICAL CONN
ECH EC23
15.99

FAN
BK 827-8024
189.99

RELAY
ECH AR566
25.99


We will go and and drive with this bus in about a week. After that I'll post back results here!

Have a good day!

 

[Clouse House]

I did something similar in a different location. While I had already fixed my overheating issue previously. I ended up adding a Honda Civic radiator in my heater core line for piece of mind and extra protection. I would say it has kept my temps in a more comfortable range. For others wanting to do something similar but wanting to spend less money, I have found these two options on ebay that work quite well.

One is an aftermarket 94-00 Honda Civic radiator w/ electric fan and shroud included for $117.99

The other is an aftermarket 79-93 Ford Mustang radiator w/ 2 electric fans and shroud included (nearly double the size) for $193.88

Both have 1.25" inlets and outlets which is the smallest radiator inlet/outlets I could find in a mass produced, popular car. Most heater hoses are 1" and we don't want too large of an increase in size, otherwise it will slow the flow of coolant through the radiator. Also being from common and popular cars, any local carpart store should have a replacement radiator on their shelves already if needed.

I would recommend a fan controller, the one linked is a very cheap ($11) and easy one that will turn the fans on once the water reaches 185 degrees and turn them back off at 175 degrees.

If you still use your heater core lines to feed hot coolant to the heater in the front of your bus and want to go full on Extra and Fancy like I did you can also use a 1" tee in conjunction with a Solenoid Valve to control the flow of coolant. If you put the solenoid on the same signal wire as the radiator fans, it will block the flow of coolant going to the radiator when the coolant is below 185 degrees while still allowing coolant to flow to the heater core. Then at 185 degrees it will start allowing water to the radiator, basically its a fancy electric coolant thermostat. The plus side is that you can also put a second signal wired to a switch on your dash in order to manually open or close the solenoid as needed to override the temperature signal. These solenoid valves are safe up to 248 degrees and 128PSI, meaning they won't have any issues in a vehicle coolant system.

 

[s2mikon]

Does your rear engine door have vents in it? Mine did not. I has them now. It was a big help and was easy and inexpensive.

 

[cadillackid]

the 7.e in RE configuration has seemingly always run hot for many people.. this is a neat way to fix it.. though you really need heat to the front for defrost.. its entirely silly to run a minisplit on the road for heat and it doesnt blow on the windshield..


I once cooled my whole 444E with all my bus heaters on high windows down and the boost pump.. i was able to drive slow and limp myself off the freeway after an idler pulley went and so went the serp belt.. those pumps are good for what you use it for.. the one thing about them though is they are not self priming but you should have enough flow with just the bus water pump..


how do you handle winter warm up? the heater line ports on a bus are fully active when the thermostat is closed so your aux radiator is getting full flow from the bus water pump even when its cold

 

[Clouse House]

the 7.e in RE configuration has seemingly always run hot for many people.. this is a neat way to fix it.. though you really need heat to the front for defrost.. its entirely silly to run a minisplit on the road for heat and it doesnt blow on the windshield..


I once cooled my whole 444E with all my bus heaters on high windows down and the boost pump.. i was able to drive slow and limp myself off the freeway after an idler pulley went and so went the serp belt.. those pumps are good for what you use it for.. the one thing about them though is they are not self priming but you should have enough flow with just the bus water pump..


how do you handle winter warm up? the heater line ports on a bus are fully active when the thermostat is closed so your aux radiator is getting full flow from the bus water pump even when its cold

Not sure about the OP, but like I said before I used tee junctions off of the heater core line and an electric solenoid actuated off of a water temperature sensor to block off the aux radiator when the temps are below 185.

Picture added for visual.

 

[mtnfreak]

So I just went through overheating issues with my 8.3 cummins RE . it had ther same issues you describe, we are pulling a 2500 # toad and weigh in at 32,000 pounds with the toad. It would get up to 220 on any long incline even at 2% grade and I had to downshift the md3060 to 3 rd gear and run it at around 1900 rpm to keep it around 200 degrees...I changed the coolant, pressure washed the intecooler and rad as best i could and no still no change. Finally last week I picked up an OEM thermostat from cummins and installed and wow what a differnce! now it stays at 180 to 190 even on hills.
The old thermostat looked fine no visible signs of failure. but might have been the original on this 2000 bluebird, anyway didnt see in your post it was something you changed out. Took me about an hour to change.