Maxxforce DT and Heat

[Clouse House]

High temperatures. Whether it's a car, bus, drink, or a person, we all hate them. I kept reading that one of the downsides to RE buses was trying to keep the engine cool. Seems fair, the engine is in the back after all. I also kept reading about how Maxxforce DT's have issues staying cool. So what did I do? I bought a RE bus with a Maxxforce DT. Cause you know Why not?

Now, before any lectures start. I understand that a properly working cooling system and engine will not overheat. Because what company out there purposefully makes an overheating engine, right? So I get that, but this world isn't perfect and I'm sure my coolant passages aren't either. That being said I currently do not have a cooling problem. What I did experience however was a cooling issue due to low hydraulic fluid to my cooling fan, and then a full blown overheat event due to faulty repairs to said hydraulic system. So naturally, now I'm paranoid about it.

I started looking more and more at my engine and no wonder they have cooling issues. Everything is reliant on the coolant, and I mean everything. The oil cooler is just transferring heat from the oil to the coolant, the transmission cooler is just transferring heat to the coolant, the hydraulic cooler is just transferring heat to the coolant, the EGR cooler is just transferring heat to the coolant and then of course the engine is transferring heat to the coolant as you would expect. So one radiator, albeit a big one, is responsible for cooling every heat producing component in my bus. That just baffles me.

Even my sedan has separate radiators for each component. The coolant has a radiator, the hydraulics have their own radiator, and the transmission has it's own radiator, and that's just a four door car.

Now not only is the engine/transmission designed to pass all of their heat over to the coolant but it's seems that these are also common failure points for these engines. The EGR coolers will fail and get coolant into the exhaust and possible the combustion chamber, and the oil cooler will fail and mix your oil and coolant. Although I haven't heard anything about the hydraulic/transmission cooler failing, I still don't like that three different fluids all run into one device with the skinniest amount of metal between them.

For the EGR there is the delete option or the Bulletproof option. So that already seems to be "resolved." That's pretty straight forward albeit expensive fix. In my case the PO replaced the EGR coolers with OEM ones about two years ago so I should be okay for awhile.

The heat exchanger responsible for allowing the transmission and hydraulics to dump their heat into the coolant is pretty straight forward too. Disconnect the fluid hoses, reroute the transmission lines and hydraulic lines to a new location and attached external coolers on them. Bypass coolant lines. Of course it's more involved than that if you want to do it right. But it's pretty straight forward.

The tricky one is the oil cooler. They make oil cooler delete kits for the DT466 that can be easily used for an external oil cooler. But that doesn't help me on the Maxxforce DT. So I think I have a decent solution, at least in theory.



The oil cooler is a heat exchanger that has coolant and oil running through it in stacked plates. But underneath that is simply four ports. Coolant in, coolant out, oil in, oil out. The grooves for the o-rings and gaskets aren't part of the the heat exchanger but rather they are part of the "Oil filter base" that the heat exchanger bolts to. So my plan is essentially to recreate the base plate of the heat exchanger out of 1/4, 3/8, or 1/2 inch steel, haven't decided yet; drill the holes for the bolts and ports. Then tap the ports to install fittings. From their I can route the coolant ports together so it flows as normal, or even run it too a small external radiator for extra heat dissipation. And I can attach the oil ports to some hoses and eventually to an external oil cooler.

Does anyone have an old Maxxforce DT oil cooler laying around and can measure the internal diameter of those ports? Knowing the port size will determine the thickness of metal for the base plate.

Does anyone think this is an absolutely horrible idea? It would separate all these different heat sources and make it so only the EGR coolers would be dumping heat into the coolant. If I had space I'd have seperate 12v waterpump and radiator for that too.

[rossvtaylor]

I can't comment on your exact plan, not having done that. But I do have a thought for you. If that modification plan becomes too much of a pain, you might look at an aircraft oil cooler. The last time I bought one new (well, rebuilt) it was just about $200. And I just did a quick ebay search for "aircraft oil cooler" and found this used one for $50. Just a thought for a quick option:

[sportyrick]

There are two sides to every coin so there are two sides to your removing heat. Your side is to just get rid of it but there are consequences to that because coolant is used to heat up your transmission, hydraulics, but I am not sure about EGR. Imagine driving around in sub-zero weather and your transmission and hyd. don't have a chance to get hot, not even warmed up, that can lead to problems with moisture, acids, hard shifts etc. Getting rid of the heat before the radiator with an after market cooler would do two things, pull heat out of your hot fluid before the radiator reducing that load and possible cool the radiator down a little bit too. Then the fluid coming out of the radiator would go back to the tranny or hyd. within the operating temperature that the manufacturer designed it for. waddya think?

[s2mikon]

Everything being "cooled" by the radiator is for temperature stability. The transmission, engine oil and hydraulic oil all need to operate within a range and the engine coolant is perfect for that. If you want to add to the capacity of your system then add a more engine cooling. A larger radiator if possible or more fan to move more air over the radiator. Adding more air will also cool the charge air going into the engine. I have seen large heavy electric cooling fans that are truck sized used on stationary diesel engines here in the oilfields. It only needs to run on high boost and high water temperatures to be useful. With a fan over ride switch it would help with hydraulic fan failures.

[s2mikon]

Here is a link Turbine Electric Cooling Fans for Buses and Off-Highway Vehicles

[Booyah45828]

Temp stability and the fact that water is way better at thermal transfer then air. The bus was designed to operate in a broad temp range, the whole death valley to pikes peak idea. If it's not operating correctly, it's likely because of a component failure, not a design failure. A design failure typically won't surface after 20+ years of service.

If you want to individualize all the coolers used on your bus, you'd have to have half the side of the bus consumed by coolers. I don't think it's a coincidence that every time I've seen someone who separates coolers to solve overheating issues didn't end up solving them.

Think of it like a boat. If the bilge pump doesn't work, then by all means replace it. But if it's not keeping up, rather then faulting the pump and replacing it, increasing it in size, or doubling up on pumps, why don't you find the source of the water leak and eliminate that?

Don't get me wrong, delete the egr/emissions on it, as I've never seen those devices increase reliability, and egr coolers are a huge source of heat in the cooling system. But if you're overheating, chances are throwing more coolers at this isn't the solution.

[Clouse House]

Originally Posted by s2mikon

everything being "cooled" by the radiator is for temperature stability. The transmission, engine oil and hydraulic oil all need to operate within a range and the engine coolant is perfect for that. If you want to add to the capacity of your system then add a more engine cooling. A larger radiator if possible or more fan to move more air over the radiator. Adding more air will also cool the charge air going into the engine. I have seen large heavy electric cooling fans that are truck sized used on stationary diesel engines here in the oilfields. It only needs to run on high boost and high water temperatures to be useful. With a fan over ride switch it would help with hydraulic fan failures.

Originally Posted by sportyrick

there are two sides to every coin so there are two sides to your removing heat. Your side is to just get rid of it but there are consequences to that because coolant is used to heat up your transmission, hydraulics, but i am not sure about egr. Imagine driving around in sub-zero weather and your transmission and hyd. Don't have a chance to get hot, not even warmed up, that can lead to problems with moisture, acids, hard shifts etc. Getting rid of the heat before the radiator with an after market cooler would do two things, pull heat out of your hot fluid before the radiator reducing that load and possible cool the radiator down a little bit too. Then the fluid coming out of the radiator would go back to the tranny or hyd. Within the operating temperature that the manufacturer designed it for. Waddya think?

Originally Posted by booyah45828

temp stability and the fact that water is way better at thermal transfer then air. The bus was designed to operate in a broad temp range, the whole death valley to pikes peak idea. If it's not operating correctly, it's likely because of a component failure, not a design failure. A design failure typically won't surface after 20+ years of service.

If you want to individualize all the coolers used on your bus, you'd have to have half the side of the bus consumed by coolers. I don't think it's a coincidence that every time i've seen someone who separates coolers to solve overheating issues didn't end up solving them.

Think of it like a boat. If the bilge pump doesn't work, then by all means replace it. But if it's not keeping up, rather then faulting the pump and replacing it, increasing it in size, or doubling up on pumps, why don't you find the source of the water leak and eliminate that?

Don't get me wrong, delete the egr/emissions on it, as i've never seen those devices increase reliability, and egr coolers are a huge source of heat in the cooling system. But if you're overheating, chances are throwing more coolers at this isn't the solution.

On my E-350 I have the trans fluid run through an external cooler and then through the radiator to make sure it is at an operating temperature, the oil is run through a oil thermostat before an external cooler. Doing something similar to the bus would be the full plan.

I wanted to originally somehow tap the OEM oil cooler so that the oil would run through an external cooler then through the OEM cooler but I figured that would be impossible, which led me to the bypass plate idea. The oil would run through an oil thermostat, much like this one from summitracing.com before going to the external cooler. The one linked is set for 180 degrees, below that temperature the oil is returned without passing through the cooler allowing the oil to come up to temperature.

For the transmission and hydraulic fluid I plan to run it to an external cooler then through the original heat exchanger for further cooling and/or heating back to operating temperatures.

And again, I don't currently have an overheating issue, but my bus is pretty empty right now, and most of my test drives are on flat ground in mild weather. When finished it will likely be close to its maximum weight, I'll be towing an SUV or Van, and travelling in areas that are either hot themselves are that will cause the bus to generate lots of heat. I have a lot of family in the NV, AZ, and TX, giving me concern for hot environment; as well as family in MD, PA, and NY giving me concern for the heat generated by mountain climbing. So what I'm doing is more just as "Heat Insurance" rather than trying to get around a failing cooling system. I also recognize that I'm going a little overkill on it, but I've always been paranoid about overheating events on any of my vehicles.

As far as beefing up the radiator, I don't believe there is room for a larger radiator nor do I think a different fan will be beneficial. Hydraulic fans are quite powerful and reliable. I do however have a plan to install an auxiliary radiator in the heater core line incase I ever need that extra capacity. I found that 1994-2000 Civic radiators are pretty small and have 1.25" inlets and outlets that match my heater core lines. They are relatively cheap on ebay with shrouds and fans too, only about $100 for everything. If I have the extra room 1979-1993 Mustang radiators are twice as wide with the same inlets and outlets, same pricing on ebay too.
Rather than the shut off valve that is installed on my heater lines now, I would put a directional valve, so I can choose between heat or aux radiator.

Thank you for showing concern for over cooling the engine as that would be a problem too, like people that take the thermostat out of their cooling system in an attempt to stop over heating. I swear, every truck, car, or van that I've purchased older than '93 has had the thermostat removed.

[cadillackid]

bypass plates or external filter adapters are how ive seen people use external oil coolers.. if the oil thermostat is a 3 port type where it can truly route oil around then an external filter adapter is a possibility as it still allows full flow.... another option is you can run to an external cooler thats fan forced and not in the windstream.. so the fan comes on when the oil needs cooled.. otherwise it might take a little heat off but not enough to worry about .. oil cooling issues on engines with perfectly fine factory coolers are often telltale signs of high amounts of blowby under heavy load.. blowby gasses are hot and will add a significant amount of heat to the oil.. you have those gasses heating up the air inside of the crankcase.. and you have oil droplets flying around in almost a mist at high speed.. that creates a near perfect heat exchanger for high temp gasses to heat the oil...

[s2mikon]

Do you have temperature gauges on the transmission, engine oil and hydraulic oil? If not I would start there just to see where you are at. When was the last time the radiator was serviced / cleaned. The egr coolers are another source of heat you could do without. Rear engine buses don't have any ram air and have very little safety margin. I'm old enough to remember when greyhound bus drivers would take a rope and tie the rear doors open a bit going up the ridge route in the summer to help with cooling. I installed rear vent holes in my rear door to stop heat build-up in the bedroom and it worked. It also cooled the engine water on a hard pull. It was easy to do. The bedroom was like an oven, now it's not.