Spacers between engine/trans cooler and radiator

[Thumper580]

I was thinking about putting 1/2" spacers between the oil/trans cooler and the radiator. My thought was by adding additional space between the two it might have better air cooling for the radiator and not run as hot all the time. Has anyone done this? and does it offer any positive effect. Thanks.

 

[Coug]

The more space between them, the more it allows air to move through in areas that have larger spacing. The closer they are together, the more evenly it will pull air through all the layers, rather than just the path of least resistance. This would lead to more uneven cooling, and if there is anywhere easier for the air to come in from (like the outside edges) the only the bottom most layer would get the full cooling effect, the other layers would be warmer with less heat dissipation.

 

[87cr250r]

Often, oil and trans coolers spend most of their time working as heaters. The help normalize the oil and trans temps with the engine coolant. Probably best to leave it in contact with the radiator.

 

[osteo16]

A lot of smart engineers developed that system... Just saying..

 

[Coug]

A lot of smart engineers developed that system... Just saying..

Are they the ones that also designed the heater and defrost systems?

 

[Milcommoguy]

Are they the ones that also designed the heater and defrost systems?

And might I add the Not so smart start system box thingie...

Just had to say it, CAMO

 

[Coug]

And might I add the Not so smart start system box thingie...

Just had to say it, CAMO

I was thinking that too, but the heat/defrost was similar enough that maybe they were designed together with the cooling stack.

 

[TOBASH]

Separating the cooling stack might have unintended consequences. It might allow air to leak in from the hot engine bay rather than from the grill.

I think a clean stack is a good stack.

 

[Thumper580]

My overall hope was that getting more air through the (coolant) radiator it would be nice if the coolant ran 10 or so degrees lower. Not so much now but central VA in the summer is HOT and HUMID, like so much of the south. Cut back on the clutch fan running so much. A little cooler wouldn't hurt.

 

[87cr250r]

Is central VA Middle East hot? The HMMWV earned it's reputation in the hottest desert.

 

[Thumper580]

Is central VA Middle East hot? The HMMWV earned it's reputation in the hottest desert.

I'm not debating that.... Wouldn't it be nicer, better, easier on the engine if it ran consistently 10-15 degrees cooler?..... Just because I might have shocks on my GMC Sierra that can take a beating doesn't mean I need to hit every pothole in the road.... These hmmwv's run on the warm side. Just thinking about giving the coolant radiator a bit more airflow.

 

[Autonomy_Lost]

I'm not debating that.... Wouldn't it be nicer, better, easier on the engine if it ran consistently 10-15 degrees cooler?..... Just because I might have shocks on my GMC Sierra that can take a beating doesn't mean I need to hit every pothole in the road.... These hmmwv's run on the warm side. Just thinking about giving the coolant radiator a bit more airflow.

I'm not an auto engineer, but I don't think that running an engine arbitrarily cooler is neccessarily better. Engines need to run at a certain temperature and the parts are designed to operate with a given thermal expansion at a given running temperature. Oil and other fluids flow properly at the right temperature as well.

This is just my opinion, but unless I had a really good reason to modify something on my humvee and had scientific evidence that it was neccessary, I wouldn't mess with it.

And if your humvee is overheating, there is something wrong and you should fix it

 

[Coug]

This topic comes up on a regular basis. People asking how to make their truck run cooler.
It's not designed to run at a cooler temp. If everything is working how it's supposed to, then the engine is operating at the correct and most efficient temperature. Trying to make it run outside of that temp range will cause issues, not fix them.

Even if you increase the cooling capacity of the radiator, the fan doesn't kick on until 220-230 degrees. The engine still operate at minimum 185-200 because of the thermostat opening temps and fan operation.
So you'll either need to change to a different fan clutch type or a different thermo switch to engage the fan circuit.
You will also need to change out the thermostat.

To put it bluntly, you're trying to solve a problem that doesn't exist.

 

[Mogman]

Coug is right the fan switch controls the temp.
One of the reasons everyone went to higher water temps in the 70s was for efficiency. (in case you were not there we were all waiting for hours in line to get gas)
ALL the heat you remove via the cooling system is fuel loss it is one of the reasons why petrol engines are so inefficient, the less heat you remove from an engine the more efficient it is.
That is why the experimental ceramic engines are so efficient, they have no cooling system and are insulated to keep all the heat in the engine.
I learned all this getting my degree in Automotive Technology in college in the 70s but this did not stop me from trying to get my HMMWV to run cooler, I have since just decided to go with the flow.
Even if you ran a lower temp fan switch you would not only burn more fuel running the fan you would also burn more fuel to heat the engine.

 

[87cr250r]

It's hard to say that coolant temperature has much effect on efficiency. The cycle is nearly adiabatic so outside temps have little effect on anything. Higher coolant temps do reduce cylinder wear rates and prevent cylinder glazing. I am going to have to provide some documentation to back this claim up aren't I? I'll see what I can find.

 

[Thumper580]

I'm only looking at the potential to allow more cooling so maybe the truck runs in the 200-205 degree range instead of 220-225 range. Can't see how that could be a bad thing. Still hot enough to operate normally.

 

[87cr250r]

Instead of chasing 5 degrees of coolant temp, run synthetic oil. Look for ester based oil if you can find it.

 

[Autonomy_Lost]

Even if we assume that cooler is better, what makes you think that adding spacers is going to increase air flow? Without spacers, all of the incoming air is forced through the oil/trans cooler and directly into the radiator. If you introduce a space, its a path for the air to divert away from the radiator instead of going through it. This might make cooling worse.

It's your truck so do as you please, but it really seems that you are making arbitrary changes to solve a problem that doesn't exist, and possibly introducing new problems.

 

[Thumper580]

Even if we assume that cooler is better, what makes you think that adding spacers is going to increase air flow? Without spacers, all of the incoming air is forced through the oil/trans cooler and directly into the radiator. If you introduce a space, its a path for the air to divert away from the radiator instead of going through it. This might make cooling worse.

It's your truck so do as you please, but it really seems that you are making arbitrary changes to solve a problem that doesn't exist, and possibly introducing new problems.

Yes it has to pass through engine/trans cooler which inhibits airflow to the coolant radiator thus reduces cooling. The air passing through the engine/trans cooler is preheated before reaching the coolant radiator. I never said this was a "problem". Simply reducing obstruction to airflow to the coolant radiator.