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Old 07-07-2019, 03:08 PM   #1
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Has anyone added a second radiator to their bus

Hi everyone. My bus will be driving across the country this august, along I-80 to northern nevada, from Ontario Canada. The bus will be fairly heavily loaded for this trip. I will be doing this trip every summer for the foreseeable future as well.

Although I don't plan on going up any extreme grades, there are quite a few larger mountain passes on that route, and it does get pretty hot at that time of year. My bus has a cat engine which already tends to run hot. I'm already thinking about adding lower temperature thermostats, the bus has 190F ones installed, I need to change them out as PM anyways, if i was doing that i might just put in 170F ones.

In addition, I'm thinking about adding in a smaller second radiator from a car or small truck where my interior heater used to connect (I've disconnected it and looped the coolant tubes), and mounting the radiator underneath the bus on a slight angle pointing down. I would then connect the electric fans on it from the donor vehicle to my buses electrical system so I can control them.

Has anyone done this before? Is there anything about this that is a bad idea?
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Old 07-07-2019, 03:16 PM   #2
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I've not done it.
And while it sounds theoretically feasible, have you made contingencies to protect this aux radiator from getting hulled by slang debris and/or road irregularities..?
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Old 07-07-2019, 05:29 PM   #3
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What transmission do you have? I'd be equally interested (I wouldn't say "worried" yet) about the transmission temperature as the engine temperature.

I'd be tempted to get the 170 thermostat installed, do the drive once, and see what happens. It could be fine, just plan a few extra hours if you need time every now and then to pull off and let the bus cool down. Then figure out if you need to spend the extra money on an aux radiator setup.
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Old 07-07-2019, 05:40 PM   #4
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A potential problem with going with a 20 degree cooler thermostat is that it might be open too much, not allowing coolant enough time in the radiator to shed enough heat. This is admittedly theoretical, based on a friend taking out his thermostat completely, which kept the coolant circulating constantly, and the engine got even hotter than before.

Using the heater connections for an aux radiator will be similar to not running a thermostat, for that radiator anyway, as it's unrestricted and returns directly to the engine block. But it will add a little volume and cooling capacity.

Like Mark, I'd be interested in transmission heat too, especially since it can contribute to engine heat. A bigger trans cooler should also help with engine heat.

Have you looked into an inline oil cooler?
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Old 07-07-2019, 06:24 PM   #5
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Stick with the stock thermostat. Flush the cooling system and refill with correct coolant. You might be able to change the ratio of the mix for better cooling but 50/50 should work also. Make sure all hoses and clamps are tight on the system, if possible take spares and spare serp belt or whatever is on it.

You could plan on travelling after dark too for cooler air and road temps which might do you well if you are heavy. Rainy weather is some help too I believe.
The thing about a thermostat change to lower temps will result in incomplete combustion of the fuel so lower mileage to be expected.
Best to take a nice comfortable drive with no time constraints to your destination, so good luck.


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Old 07-07-2019, 07:29 PM   #6
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Quote:
Originally Posted by JustKip View Post
A potential problem with going with a 20 degree cooler thermostat is that it might be open too much, not allowing coolant enough time in the radiator to shed enough heat. This is admittedly theoretical, based on a friend taking out his thermostat completely, which kept the coolant circulating constantly, and the engine got even hotter than before.
The idea that coolant flow can be too fast to shed heat through the radiator is a popular myth. All else being equal, the faster the flow through the system, the faster the rate of potential heat transfer, limited by the radiator's ability to shed said heat. Not that I disagree with what you said concerning your friend - many people have done the same and reported similar results.Could be cavitation from reduced back-pressure. Could be other causes too. But it's not because the coolant doesn't have enough time in the radiator.

Regardless, a lower-temp thermostat wouldn't affect flow rate one way or another once up to temp. It will simply open sooner, which means it will take longer for the engine to warm up to operating temperature. At low loads / short operating duration, you'll run cooler, but it won't have any significant impact on overheating. At 191-degrees coolant temp (and up), a 170-degree thermostat and a 190-degree thermostat are both fully open, and effectively exactly the same.

I don't think a -20 thermostat is good idea either, but for different reasons. Running a lower-than-design thermostat can increase engine wear, increase emissions, and most of all - throw away power & fuel efficiency. Heat is energy. The only reason we remove it via cooling systems is because the engine components can only take so much of it. Removing more than necessary is literally burning fuel to heat the air around your radiator. If your engine is designed around a 190-degree thermostat, that's where it's happy.

Quote:
Originally Posted by Mark_In_MA View Post
What transmission do you have? I'd be equally interested (I wouldn't say "worried" yet) about the transmission temperature as the engine temperature.
Quote:
Originally Posted by JustKip View Post
Like Mark, I'd be interested in transmission heat too, especially since it can contribute to engine heat. A bigger trans cooler should also help with engine heat.

Have you looked into an inline oil cooler?

These are great suggestions. Probably easier to implement that what the OP was thinking and would actually be more effective removing heat where it can cause the most harm (and the least good). I was thinking of ways to improve our cooling system efficiency as well and while I had a 2nd trans cooler planned I hadn't even though of an oil cooler. Gracias!
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Old 07-07-2019, 07:58 PM   #7
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Quote:
Originally Posted by Mark_In_MA View Post
What transmission do you have? I'd be equally interested (I wouldn't say "worried" yet) about the transmission temperature as the engine temperature.

I'd be tempted to get the 170 thermostat installed, do the drive once, and see what happens. It could be fine, just plan a few extra hours if you need time every now and then to pull off and let the bus cool down. Then figure out if you need to spend the extra money on an aux radiator setup.
Allison MD3060 with the deep sump trans fluid pan

I don't believe it has a supplementary cooler other than what is on the transmission. I could definitely look into adding that.
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Old 07-07-2019, 08:33 PM   #8
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If you're overheating, putting in a lower temp thermostat doesn't change anything other than when it opens and starts to circulate. It won't help what's causing it to run hot.
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Old 07-07-2019, 08:35 PM   #9
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Quote:
Originally Posted by Ab01ns View Post
Hi everyone. My bus will be driving across the country this august, along I-80 to northern nevada, from Ontario Canada. The bus will be fairly heavily loaded for this trip. I will be doing this trip every summer for the foreseeable future as well.

Although I don't plan on going up any extreme grades, there are quite a few larger mountain passes on that route, and it does get pretty hot at that time of year. My bus has a cat engine which already tends to run hot. I'm already thinking about adding lower temperature thermostats, the bus has 190F ones installed, I need to change them out as PM anyways, if i was doing that i might just put in 170F ones.

In addition, I'm thinking about adding in a smaller second radiator from a car or small truck where my interior heater used to connect (I've disconnected it and looped the coolant tubes), and mounting the radiator underneath the bus on a slight angle pointing down. I would then connect the electric fans on it from the donor vehicle to my buses electrical system so I can control them.

Has anyone done this before? Is there anything about this that is a bad idea?
How hot are you talking?
Mine runs 220 all day but never overheats.
FWIW my Cat is way cooler running than any DT466E or 444E I've had.
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Old 07-07-2019, 10:56 PM   #10
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Originally Posted by EastCoastCB View Post
How hot are you talking?

Mine runs 220 all day but never overheats.

FWIW my Cat is way cooler running than any DT466E or 444E I've had.
Mine is about that in the sun. Admittedly this in very flat Ontario Canada and not pulling hills or heavily loaded
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