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Discussion Starter · #1 ·
Over the years the issue of a bigger radiator for us, to replace the little dinky one we have, has been discussed on and off. Did anything come of those discussions? Did an aftermarket larger radiator ever become available?

I see that folks have been fiddling around with oil coolers. But if we could just keep the coolant cooler, we wouldn't need oil coolers.
 

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Personally I think the oil cooler is the easier way to go and I believe that people who have don't the oil cooler delete have also reported lower coolant temps.
 

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Discussion Starter · #3 ·
Attempting to cool oil is no way to cool an engine.

1) Oil doesn't exchange heat very well. Not nearly as well as water. So engine doesn't xfer heat to it well, and air flow doesn't extract heat from it well.

2) Water cooled engines are designed to xfer heat to the water, not to the oil. Look at how the engine block and head are designed such that the water jacket surrounds the entire cylinder and almost the entire top of the combustion chamber.

Te objective of cooling oil is to limit the peak temps of the oil. This extends oil life and keeps viscosity changes under control. Cooling the engine is not an objective. A feckless dribble of oil thru a little oil cooler, the oil resistant to giving up heat energy, is no way to design a cooling solution capable of significant load.
 

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I see that folks have been fiddling around with oil coolers. But if we could just keep the coolant cooler, we wouldn't need oil coolers.
I disagree. I've never had an issue with high coolant temps when towing heavy. Can't say the same for oil.

Since installing my oil cooler my oil temps are much cooler, and thus my coolant stays cooler as well due to the lack of being heat-soaked from the oil.

A feckless dribble of oil thru a little oil cooler, the oil resistant to giving up heat energy, is no way to design a cooling solution capable of significant load.
Apparently you haven't seen my oil cooler lol.
 

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Discussion Starter · #5 ·
I disagree. I've never had an issue with high coolant temps when towing heavy. Can't say the same for oil.

Since installing my oil cooler my oil temps are much cooler, and thus my coolant stays cooler as well due to the lack of being heat-soaked from the oil.

Apparently you haven't seen my oil cooler lol.
Re. coolant temps vs. oil temps. Those are different issues. The engine is putting lots of heat energy into the coolant, and not much into the oil. The OEM set up has the radiator to extract heat from the coolant, but nothing to extract heat from the oil. Isn't surprising, therefore, that our oil runs hot.

What people in this forum tend to call an oil cooler, isn't. It's just a heat exchanger to allow quick warm up of the oil in cold climates. Easy to do when coolant is 200deg and oil at 0deg. That's a 200deg delta. But when the coolant is at 225deg and the oil at 240deg, it's only a 15deg delta and w/o much surface area to xfer heat between fluids, it won't do much.

Just the fact that people are calling the OEM heat exchanger an "oil cooler" should cause everyone to be wary re. oil cooling opinions here.

Unless your oil cooler is huge, it's not going to do much. Remember that oil doesn't xfer heat well so oil coolers have to be really big to xfer noticeable thermal energy. Otherwise all they do is cut off the peak oil temps. Some oil cooler that is maybe 1' by 2" isn't going to dump enough thermal energy to matter. Remember, the coolant thermostat is a dynamic flow control device. It will attempt to keep the coolant at it's designed temp by changing the valve's position and therefore flow rate. So the larger oil cooler will not change the temp of the coolant until the heat load goes beyond what the fully open thermostat can handle, call it 225deg. Beyond that, the engine can use all the help it can get. So the way to tell if the oil cooler is helping is not lower engine temps, but lower incidents of coolant going >225deg, all else being controlled to be equal.

There is no "thus my coolant stays cooler". At least not w/o rigorous experiments. One of these days find a way to get your hand behind an oil cooler with hot oil in it. Blast air at it's face. You will find that the air hitting your hand isn't warmed much at all. Oil does not xfer heat well and there isn't much oil moving thru the cooler. Therefore not much thermal energy dumped.

The flow rate thru the oil cooler is the flow rate of oil out of the pump. At 35 or so PSI, it's the kind of dribble you'd expect from water pouring out of a 1/2" hose. No matter how big the oil cooler, you won't get more oil flow rate.

10yrs ago I did some experimenting with oil coolers on my race car. I put in a big oil cooler, 12x18", and put in oil temp sensors before and after. I was getting a lot more air blast on that oil cooler than a truck gets because race cars are allowed to go much faster. The best temp delta I could get was 2.5deg between in and out sensors. Consider how miniscule that much thermal energy must be. Over time tho, it added up. As I said, oil doesn't xfer heat well, but that's a 2 way street. Consider that my entire oil load was probably going thru the oil cooler every 2min (that's a guess btw) and every time the oil went thru the engine, it gained only enough thermal energy to raise the temp 2deg. In that scenario the oil temp drops 0.5deg with every circuit thru the oil cooler. That's how oil coolers drop peak oil temps. But as you can see from that example, it wasn't pulling much thermal energy out of the engine.
 

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Dodge Heavy Duty Cooling by CSF Radiators, the cooling experts.. Click the view button on 3738

It’s what Sasquatch sells. Basically quality stock replacements. Fwiw 1/2 the price a dealership charges.


No the oil cooler/heat exchanger is not for cooling the engine. That remains the radiators job. We are having foremost an elevated oil temp problem where in the computer can derate the engine by pulling back fuel. The two best oil cooler set ups to replace the heat exchanger are reported to help. First & foremost keeping the oil temps down so that no oil temp derate happens. The side benefit less load on the radiator from not having to cool the oil also helps to keep coolant temps in check which is also an issue when towing TTs in really hot humid weather.

So directly & in directly it helps with both issues. At least that is my understanding. A concern I had was that replacing the heat exchanger also takes away the heat exchanger for the transmission. Unless I am mistaken about that. Regardless nobody who uses one of the aftermarket oil coolers has yet to complain about elevated trans temps or uber slow trans warm up.

I’ve always though more “plates” in the existing heat exchanger might be the best all around solution. Well in conjunction with bigger radiator / tanks. Next generation with the incredibly strong 48 volt fan should help tremendously.

Edit ok FYI I typed this post prior to RGs last post.
 
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I see that folks have been fiddling around with oil coolers. But if we could just keep the coolant cooler, we wouldn't need oil coolers.
Its like you have just written off the oil cooler as relevant and refuse to consider it. There are many using it... and guess what it works.
 

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I think a better rad would be the proper way to remove engine excess heat , that is its main function . Remember we have a electric fan and there not as good a a viscous fan clutch unit . I rather spend my money on a rad then a $ 1000 dollar oil cooler setup with all the extra plumbing and the possibility of a blown line while driving .
 

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Discussion Starter · #9 ·
Its like you have just written off the oil cooler as relevant and refuse to consider it. There are many using it... and guess what it works.
Oil cooler not written off. Oil coolers are a fine means to cool oil. They're just not an efficient means to cool engines. For cooling engines we have a radiator and water-based coolant. Even if the radiator is on the small side.
 

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During ascents while towing, why is it the oil temp climbs so quickly while the coolant doesn't? Where is the oil scavenging all the engine heat from under a heavy load?

VernDiesel said:
A concern I had was that replacing the heat exchanger also takes away the heat exchanger for the transmission.
How does this affect the transmission temps? I don't understand how the transmission comes into play between the oil and coolant interaction.
 

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We use to use air cooled motors , now progress to water cooled as its way more efficient . Cheaply design radiator for this application to save some $$$$$$$$$
 

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Attempting to cool oil is no way to cool an engine.

1) Oil doesn't exchange heat very well. Not nearly as well as water. So engine doesn't xfer heat to it well, and air flow doesn't extract heat from it well.

2) Water cooled engines are designed to xfer heat to the water, not to the oil. Look at how the engine block and head are designed such that the water jacket surrounds the entire cylinder and almost the entire top of the combustion chamber.

Te objective of cooling oil is to limit the peak temps of the oil. This extends oil life and keeps viscosity changes under control. Cooling the engine is not an objective. A feckless dribble of oil thru a little oil cooler, the oil resistant to giving up heat energy, is no way to design a cooling solution capable of significant load.
You are the second one who will be called having to much vodka....


Just kidding.

I tried to discuss this issue from theoretical point of view, but some people can't go this way, they need to have their hands on...
 

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Attempting to cool oil is no way to cool an engine.

1) Oil doesn't exchange heat very well. Not nearly as well as water. So engine doesn't xfer heat to it well, and air flow doesn't extract heat from it well.

2) Water cooled engines are designed to xfer heat to the water, not to the oil. Look at how the engine block and head are designed such that the water jacket surrounds the entire cylinder and almost the entire top of the combustion chamber.

Te objective of cooling oil is to limit the peak temps of the oil. This extends oil life and keeps viscosity changes under control. Cooling the engine is not an objective. A feckless dribble of oil thru a little oil cooler, the oil resistant to giving up heat energy, is no way to design a cooling solution capable of significant load.
Wow You are making a lot of assumptions. At least I hope that is what drives this discussion.
The specific heat of oil is about 2.3 kj/kg. For water it is about 4.1 kj/kg. Ok that means oil has 56% of the heat carrying capacity of water. But coolant is not water. Coolant has 50% antifreeze and 50% water. Antifreeze has about the same specific heat as oil. Actually a little less but not much. So basically coolant has about 3.2 kj/kg specific heat. So oil has about 71% of the cooling capacity of coolant. Significant but not critical difference. The point is saying "Oil doesn't exchange heat very well" is not accurate.

Air has a far lower specific heat, about 1kj/kg. That is why a liquid to liquid heat exchanger does not need to be nearly as big as a liquid to air heat exchanger. Yes our oil to coolant heat exchanger is not big but for normal driving it does not need to be. If you were to take it apart I am pretty sure you would find 10 or 20 sq inches of area. That is just a guess but I think it is valid.

Coolant is for cooling the outside of the engine. Specifically the outer cylinder walls and the area around the combustion chamber. Oil cools the piston, bearings and rotating parts. It removes many thousands of btu of heat from the engine. If your heat exchanger on your race car only dropped the temp by 2.5 deg perhaps you need to reexamine the design. Modern oil coolers usually have turbulators or flattened cooling tubes to provide more surface contact between the oil and cooling surface. Also it would require a large amount of moving air to extract the heat. if you feel that there is a dribble of oil through the oil cooler try removing an oil line and see how long it takes to empty the 10 qts of oil in the engine. I think you will be surprised. I have seen the result of a blown oil line on my tractor and it probably took less then 20 seconds to empty the 8 qts of oil in it.

The point of this discussion is this: Oil plays a major part in keeping an engine cool so a well designed heat exchanger is critical to making the engine live.

Mark
 

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I'm running my winter front cuz my oil cooler is a little too efficient. My oil temp is running about 20° cooler at highway speeds than idling at a stoplight. The 20° drop, coupled with the minimal airflow, tells me the oil cooler is fairly efficient for my needs.
 

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Re. coolant temps vs. oil temps. Those are different issues. The engine is putting lots of heat energy into the coolant, and not much into the oil. The OEM set up has the radiator to extract heat from the coolant, but nothing to extract heat from the oil. Isn't surprising, therefore, that our oil runs hot.

What people in this forum tend to call an oil cooler, isn't. It's just a heat exchanger to allow quick warm up of the oil in cold climates. Easy to do when coolant is 200deg and oil at 0deg. That's a 200deg delta. But when the coolant is at 225deg and the oil at 240deg, it's only a 15deg delta and w/o much surface area to xfer heat between fluids, it won't do much.

Just the fact that people are calling the OEM heat exchanger an "oil cooler" should cause everyone to be wary re. oil cooling opinions here.

Unless your oil cooler is huge, it's not going to do much. Remember that oil doesn't xfer heat well so oil coolers have to be really big to xfer noticeable thermal energy. Otherwise all they do is cut off the peak oil temps. Some oil cooler that is maybe 1' by 2" isn't going to dump enough thermal energy to matter. Remember, the coolant thermostat is a dynamic flow control device. It will attempt to keep the coolant at it's designed temp by changing the valve's position and therefore flow rate. So the larger oil cooler will not change the temp of the coolant until the heat load goes beyond what the fully open thermostat can handle, call it 225deg. Beyond that, the engine can use all the help it can get. So the way to tell if the oil cooler is helping is not lower engine temps, but lower incidents of coolant going >225deg, all else being controlled to be equal.

There is no "thus my coolant stays cooler". At least not w/o rigorous experiments. One of these days find a way to get your hand behind an oil cooler with hot oil in it. Blast air at it's face. You will find that the air hitting your hand isn't warmed much at all. Oil does not xfer heat well and there isn't much oil moving thru the cooler. Therefore not much thermal energy dumped.

The flow rate thru the oil cooler is the flow rate of oil out of the pump. At 35 or so PSI, it's the kind of dribble you'd expect from water pouring out of a 1/2" hose. No matter how big the oil cooler, you won't get more oil flow rate.

10yrs ago I did some experimenting with oil coolers on my race car. I put in a big oil cooler, 12x18", and put in oil temp sensors before and after. I was getting a lot more air blast on that oil cooler than a truck gets because race cars are allowed to go much faster. The best temp delta I could get was 2.5deg between in and out sensors. Consider how miniscule that much thermal energy must be. Over time tho, it added up. As I said, oil doesn't xfer heat well, but that's a 2 way street. Consider that my entire oil load was probably going thru the oil cooler every 2min (that's a guess btw) and every time the oil went thru the engine, it gained only enough thermal energy to raise the temp 2deg. In that scenario the oil temp drops 0.5deg with every circuit thru the oil cooler. That's how oil coolers drop peak oil temps. But as you can see from that example, it wasn't pulling much thermal energy out of the engine.
This is exactly how I tried to approach oil cooling (even called oem "oil cooler" heat exchanger)...

First we need to agree if this power plant has heat problem as a general...

The main device to reject heat in this application is coolant radiator (the second is engine itself.... not too effective, but still there).

Do we have coolant overheating problem when tow hard, or long or fast or all together ???

From heavy duty users (not me...) we can see no such problem exists (unless somebody is trying to tow 10k trailer over 6 grade and keep 70 MPH)

But most of the heavy duty users do say oil temps are climbing in "red" zone of 265-270 F and as safety measure engine software start defueling and slow you down to acceptable temps levels.


This engine has oem oil heat exchanger which is a great idea because it suppose to keep oil temps and coolant temps at par.

Oil heat exchanger is much better idea, than air cooled oil radiator because it keeps oil and coolant temps closely correlated. Why would you like coolant temps at 210-220 F and oil temps at 80-100 F? This doesn't make any sense.

Oil heat exhanger is only a great idea if main coolant radiator has extra cooling capacity to cool oil as well as coolant.

Now why oer oil temps a getting too hot???

There are few becauses...

1. oil heat exchanger is too small (not enough area or wrong design to have efficient heat exchange)

2. oil flow or coolant flows or both that flow through it to exchange heat are not enough (more flow more opportunity for liquids to exchange heat)

3. Some other devices (thermostats, valves etc) making heat exchanging process not efficient enough.
 

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There are at least 3 things that affect heat exchanger performance:

1. Size. The bigger, the more heat can be exchanged.

2. Design. Most HX have their plates specifically bent to create turbulent flow, which makes HX more efficient. Different thicknesses, different materials.

3. Flow. Flows on both sides. If oil is pumped like crazy, but coolant is too slow, no heat exchange will occur.
 

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So summing up:

If oem oil heat exchanger was

1. big enough

2. designed right

3. enough flow on both sides.

Our oil temp would follow coolant temps no matter what.

So there is/are a problem/problems some were in 1-3 above
 

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I'm running my winter front cuz my oil cooler is a little too efficient. My oil temp is running about 20° cooler at highway speeds than idling at a stoplight. The 20° drop, coupled with the minimal airflow, tells me the oil cooler is fairly efficient for my needs.
Or just because you butchered your active shutters.... just saying :) :) :)
 
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