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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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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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Old 07-08-2019, 12:31 AM   #11
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Our CAT 3126 also runs hot. The stock temperature regulators open at 190 degrees and at idle, that is the MAX I have been able to get it to run (even with a piece of cardboard covering th radiator).


The other day, we took a trip out and about in 92 degrees F ambient temperature and at 65 MPH with the CAT turning 2300 RPM, she was right at 220 degrees (coolant temperature). Soon after I was back down to 45 MPH or less, the temperatures dropped to about the 200 degree mark.
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Old 07-08-2019, 12:41 AM   #12
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I'm giving some serious consideration to adding a second radiator to my bus. Detroit 2-strokes are notoriously hard to cool in RE buses, and even after completely rebuilding my entire cooling system a few years ago to correct some worsening overheat problems, my temperatures are still not quite where I would like them to be. I have a space on the opposite side of my stock radiator where I could just squeeze in a radiator for a Ford F-250 / Expedition, they're only a few hundred dollars and available everywhere, and I have a 1" coolant outlet for it on one of my thermostat housings that now supplies my heaters and front defroster. Those heaters are a total of 150,000 BTU, and when I turn them on they will drop my coolant temps a few degrees when climbing long 6% grades in hot weather. As long as a Ford radiator will have at least 150K heat rejection, it will be worth it. I can use four 14" Hayden electric fans with it, and I'll run the fans and extra coolant booster pump from my house batteries that are being constantly recharged by my solar panels even when driving down the road. The only question I have now about doing this is finding what the true heat rejection numbers are for different radiators - manufacturers are shy about revealing this info, but this is central to deciding the feasibility of my plan.

Folk with older MC7 and MC8 buses with 8V71s often have overheating issues because their original radiators are undersized, especially if an automatic transmission replaced the original manual or if an 8V92 has been fitted; using extra radiators is not uncommon for them, sometimes having one across the back or sometimes smaller ones next to the original radiators. Either way, they work. There are a few folk on BCM who've done this.

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Old 07-15-2019, 11:00 AM   #13
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I wouldn't worry about it. If you are though, spend your energy on making sure the cooling fan works, the hoses and cap are all new, the coolant is in good condition, and the radiator is clean both inside and out. If you're really worried, a coolant flush can remove all doubt on system cleanliness.

Keep the 195 stats, that's what the engine was engineered to run at.

Unless it's puking coolant out the overflow, it's not overheating.
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Old 07-15-2019, 11:31 AM   #14
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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?
Put the original heater back in and duct the out put outside of the vehicle.
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Old 07-15-2019, 12:23 PM   #15
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Ditto on the heater to cool things off.

A 2nd radiator instead of the rear heater in my bus is an idea. I can use the two big water lines that go to the rear heater and run them through a radiator capable of the correct flow, etc.. Shorten them and mount the rad2 somewhere cool.
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Old 07-15-2019, 12:31 PM   #16
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Maybe consider adding an EGT gauge. This will give you rapid feedback to how the powertrain is responding to your throttle input. It might assist you in finding the best operating point (road speed, transmission gear, engine RPM) from a heat perspective so that you can minimize the cooling load as terrain and ambient conditions change. That could help you make adjustments much sooner than "oh, it's suddenly uncomfortably hot; now what?"
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Old 07-15-2019, 12:50 PM   #17
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+1 on an EGT guage.. for a lot of reasons... but primarily it is a real good indicator of whether you are in the wrong gear... ie are you lugging?


if you have low RPMS and you watch your EGT gauge start spiking quickly, chances are you are lugging.. which maskes lots of heat and is tough on the engine..



the bus manufacturers Love to run these things up to the highest gear possible as fast as possible.. moreso with the electronic transmissions(1000,2000,3000 allisons) than with the old mechanical autos (AT545, MT643)...



while you dont necessarily want to have your engine screaming at its redline.. your diesel will likely wantto run a bit higher RPM at lighter and mid throttle than you may expect...



I adjusted several of my shift characteristics after I installed the EGT gauge on my 444E...


pulling hills you will have a much happier anmd cooler run up if you downshift at the T-handle or pushbutton (ior stick if you are lucky to have a manual)... and run up the hill at higher RPMs maybe less throttle..



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Old 07-15-2019, 02:00 PM   #18
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I am not familiar with your engine setup (RE,FE etc.) but you could also try and force more air to your radiator by adding some ducting to funnel air from the side or front. For example, I know some have added louvers on the vents of their RE buses.
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Old 07-20-2019, 03:44 PM   #19
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I'm amazed that no one on the thread has suggested adding an auxiliary electric fan (or more than on) to increase cooling air flow. These are typically mounted in FRONT of the radiator, as they need no mechanical connection to the engine.
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Old 07-20-2019, 04:21 PM   #20
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Cross country trip

The bus engineers considered any overheat difficulties. If the bus overheats the reason should be determined. Usually radiator partially restricted is the main cause for any overheating. A separate engine coolant gauge is very valuable. Have radiator checked for poor cooling. A good radiator cap is required with 15 pounds pressure. After installing a good gauge, also install a temp sender on transmission cooler line. Install a switch to view the trans or engine temp. Usually the equal mix of coolant and distilled water will make a good coolant. Any bus should not overheat with original equipment. A lot of money was spent on engineering engine cooling. Frank
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