Few Questions On Improved Cooling

Tage · November 27, 2008

I have a 2003 Denali XL that I use to haul the kids around and tow an enclosed trailer a couple times per month. It runs really hot when going up hills so I will be adding a transmission cooler. I noticed that the vehicle currently has transmission has fluid lines that run through the radiator as well as a small aux trans cooler at the front grill.

Questions:

1. Should I bypass the radiator all together and have the trans lines go straight to the new larger trans cooler only? I'm thinking there will be less heating of the engine coolant by doing this, but on the flip side there won't be as much transmission fluid cooling as a result.

2. Should I use the OEM trans cooler as an oil cooler? If so, do I use as an aux cooler or bypass the radiator as well?

3. My alternator recently crapped out on me so I went ahead and upgraded to a 130A alternator with the thought that I would do an electric fan as well. My thoughts were less work needed from the engine to spin the fan might mean less overall heat generated. However, looking at fans like this it mentions that electric fans shouldn't be used as primary fans under extreme duty. I know that electric fans free up power but does this mean or imply that a good electric fan like this can't provide the same amount of flow/cooling as the stock belt driven clutch fan?

http://www.autopartswarehouse.com/details/...04QQF21292.html

Any replies or partial answers welcomed!

L29er · November 27, 2008

Electric fans are not generally recommended for towing, my truck runs hotter towing with the electric fans than it did with the old boat anchor clutch fan, I recommend keeping the fluid going through your rad, it will prevent the fluid from freezing in winter conditions (IF applicable) and just upgrade the auxillary unit, plus also checkinto DERALE, they make pretty sweet deep sump trans pans that cool a claim 20f easily with their design, plus i increases the oil capacity...>stump

Tage · November 28, 2008

I appreciate the reply.

I was looking forward to a little extra power from an electric fan but I guess you saved me $500+. My primary goal is to lower water and trans temps while towing though (increased power would only be a bonus). I live in Phoenix, AZ so freezing conditions is never an issue.

Will I run cooler (trans temps) by bypassing the radiator?

On the flip side, water and trans temp seem to go hand in hand so will I technically increase my cooling ability of both if I simply upgrade the trans cooler and leave the plumbing as is?

I'm also curious if it's worthwhile to use the current trans cooler as an oil cooler? I would think so, but the fact that it's mounted in front of the radiator and all the heat that gets transferred back into the air is simply going to hit the radiator once again.

merlin5577 · November 28, 2008

I appreciate the reply.

I was looking forward to a little extra power from an electric fan but I guess you saved me $500+. My primary goal is to lower water and trans temps while towing though (increased power would only be a bonus). I live in Phoenix, AZ so freezing conditions is never an issue.

Will I run cooler (trans temps) by bypassing the radiator?

On the flip side, water and trans temp seem to go hand in hand so will I technically increase my cooling ability of both if I simply upgrade the trans cooler and leave the plumbing as is?

I'm also curious if it's worthwhile to use the current trans cooler as an oil cooler? I would think so, but the fact that it's mounted in front of the radiator and all the heat that gets transferred back into the air is simply going to hit the radiator once again.

Possibly, it really depends on the size and efficency of your aftermarket cooler. The factory cooler does a decent job. If your going to add an additional cooler, I would plumb it in line with your existing cooler.

I believe your truck already has an oil cooler so an additional one should not be necessary. If not, I would buy a cooler specifically designed for oil as the temperatures of oil are usually much higher then the water or transmission fluid.

C & A s Dad · November 29, 2008

Tage, my truck is an 02 Yuk Xl and I tow a 6500 lb camper in the Mississippi heat in the summer. I upgraded my OE trans cooler to one of the same stacked plate design but about twice as large. My cooler is a CARQUEST Premium model by Hayden and is 11 x 11 x 3/4 thick. You want to stick with the 3/4" model and not the thicke 1.5 model as the thinner models offer better surface to air heat transfer. I would not recommend bypassing the radiator for any reason. No OE MFG I know of bypasses the radiator and the aftermarket companies I am familiar with agree.

I monitor my trans temps with an Aeroforce Scan Gauge and run temps in the low to mid 160 range on a 95+ degree day towing my camper. My engine temps run right at 195 but will hit 200 on occasion.

Here is a shot of mine installed. I have about 7 or 8 good pics I can send you via e mail if that would help you.

Bowler807 · November 29, 2008

I don't agree with Stumpuller454 about the electric fans. If they are sized correctly they will do a better job. In fact GM changed and installed electric fans in their trucks in 05 or 06. I had an 06 5.3 with electric fans and pulled a 6500# 30 foot camper and never had a problem. My new 08 also has the electric fans.

I have seen many clutch fans fail over time. Perhaps your clutch is not engaging properly and the fan is "freewheeling". If this is the case, you will not have proper cooling for either your engine or transmission.

L29er · November 29, 2008

If that were true the 6.0ls the old8.1ls and even the durrys would be running electric fans.....I have 5,900cfm fans and i don`t over heat, it just runs "a little hotter" is all i`m saying, but i have a BIG *** 454, it may be fine in a 1/2 ton, i dunno.

Hey tage, maybe look into a lower engine thermostat too, you may have to tune the truck for it but it would bring all the temps down.....(:

Tage · November 30, 2008

Great info guys! I really appreciate the help.

FYI the truck does have an oil cooler but it's simply plumbed and build into the radiator again. I'm not sure if the oil temps are a problem but I was looking to reduce the heat soak of the radiator.

I'm thinking I may have an air bubble or other cooling system problem though. In the summer (Phoenix w/110+ degree heat) it will overheat idling in my driveway with the AC on full blast. The fan and clutch appear to be working just fine. Oh some possible key imformation is that when I first got the truck I replaced the air compressor. I had to remove the coolant distribution block to get the compressor on/off which released a lot of coolant. I filled it back up but I imagine that would be prone to introducting air into the system. I didn't see a bleed valve. Does this need to be added or do the 6.0L engines not have a problem with getting air into the system and overheating?

BTW, I ordered this trans cooler so it looks to be comparable --> http://www.etrailer.com/pc-TRAN~HH41311.htm

I'm not sure I understand the theory of a lower temp thermostat. Sure it would run cooler "initially" because the valve opens earlier but with sustained load I'd think it would overheat just the same, no?

Oh and what do you guys think about the electric fans I posted originally? The two fans replace the single belt driven clutch fan and they pull 28 Amps so I have to imagine they move a good amount of air. Simply the fact that the add warns not to be used as a primary fan for a diesel engine makes me skeptical on their ability to move enough air.

Starrman · November 30, 2008

when you opened the system to replace the compressor, did you hook up a vac pump and pull a vacuum on the system to remove any moisture that might have gotten in?

Tage · December 1, 2008

when you opened the system to replace the compressor, did you hook up a vac pump and pull a vacuum on the system to remove any moisture that might have gotten in?

Ahhh, a bit off topic but "yeah". AC works great. Any more input on my overheating problems?

txab · December 1, 2008

I would replace the fan clutch for good measure. They decline in efficiency over time. You've got one 6 years old with miles pulling a load. You may think it is working great, but it may not be. If you're putting all these additional coolers on your truck, might as well make sure you've got the air for them. Make sure your a/c condenser and radiator fins are clean from bugs and debris. You can soak them down with something like "simple green". It'll soften the bugs. There are great cleaners I use for cleaning HVAC coils and cond., and I use them on my vehicle, but they must be used with care. Also make sure your fins are not bent closed to badly. Straighten them if necessary. All these things affect airflow through the radiator.