M1008 external trans cooler

[mbavers]

Plow truck only. I am replacing my radiator and am contemplating placement and routing of my external transmission cooler. Most people seem to route the trans fluid through the engine radiator first, then to the ext. trans cooler, then back to transmission. I feared that, on very cold days, the trans fluid may get too cold to perform optimally, so I routed it to the ext. cooler first, then to the radiator ( to partially re-warm it), then back to trans. Yeah, I could hook up temp gauges and experiment under different conditions, but I'm an old guy and time and patience are limited. Operating temps for plowing are anywhere from below 0F to 35F. What would you do?

 

[antennaclimber]

From the Hayden Web page:

Should the cooler be installed before or after the radiator?


Answer: We recommend installing the auxiliary cooler after the radiator to return the coolest fluid directly to the transmission. Installing the cooler before the radiator will still provide additional cooling and may be necessary in some difficult-to-access applications.



Can you over cool the transmission fluid?


Answer:


Some transmission problems really are unique to the cold weather while others get worse. Metal components contract as they get colder which results in component mates loosening up, parts wearing quicker due to friction from reduction in clearances between components, and can develop leaks from shrinkage and hardening of seals and gaskets.

The ideal operating temperature for a transmission is 180°F. The viscosity of transmission fluid changes and gets more viscous at lower temperatures. As the transmission fluid (ATF) falls below 32°F, its viscosity becomes significantly higher, restricting where it can flow to lubricate the internal components of a transmission, leading to premature wear. The use of synthetic ATF fluids is recommended where its viscosity at cold temperatures is lower than petroleum based ATF fluids.


It is critical in extreme cold conditions to use the original equipment cooler in series with an auxiliary or by-pass cooler and allow the vehicle to warm up before driving.


Hayden Transmission Oil Cooler FAQs

 

[sneekyeye]

Running it through the OE style radiator cooler second is fine. People will argue about anything, but your way is fine. It will likely not get overly warm anyhow in the cold weather through the main radiator, but in your cold temps, it could help.

 

[mbavers]

From the Hayden Web page:

Should the cooler be installed before or after the radiator?


Answer: We recommend installing the auxiliary cooler after the radiator to return the coolest fluid directly to the transmission. Installing the cooler before the radiator will still provide additional cooling and may be necessary in some difficult-to-access applications.



Can you over cool the transmission fluid?


Answer:


Some transmission problems really are unique to the cold weather while others get worse. Metal components contract as they get colder which results in component mates loosening up, parts wearing quicker due to friction from reduction in clearances between components, and can develop leaks from shrinkage and hardening of seals and gaskets.

The ideal operating temperature for a transmission is 180°F. The viscosity of transmission fluid changes and gets more viscous at lower temperatures. As the transmission fluid (ATF) falls below 32°F, its viscosity becomes significantly higher, restricting where it can flow to lubricate the internal components of a transmission, leading to premature wear. The use of synthetic ATF fluids is recommended where its viscosity at cold temperatures is lower than petroleum based ATF fluids.


It is critical in extreme cold conditions to use the original equipment cooler in series with an auxiliary or by-pass cooler and allow the vehicle to warm up before driving.


Hayden Transmission Oil Cooler FAQs

Thank you. I did not get an email notification of your reply, so my response is late.

 

[87cr250r]

I would run it through the trans cooler first then radiator. The driver's side tank is a constant 180 degrees F as that is when the thermostat opens. There is no flow through that tank during warmup so the trans cooler will not delay the warmup of the engine. If the trans cooler is cooling the fluid below 180, then that will be extra capacity for the engine as it gets heated back to 180 in the radiator.

 

[mbavers]

I would run it through the trans cooler first then radiator. The driver's side tank is a constant 180 degrees F as that is when the thermostat opens. There is no flow through that tank during warmup so the trans cooler will not delay the warmup of the engine. If the trans cooler is cooling the fluid below 180, then that will be extra capacity for the engine as it gets heated back to 180 in the radiator.

Thanks!

 

[Curtisje]

I agree with 87cr250r. Run your fluid from the tranny to the external transmission cooler and then through the radiator.

I've read several external cooler manufacturers instructions and they all seem to recommend the opposite. Here is my rationale:

I have 2 trucks that tend to overheat the engine during heavy towing, my 2001 Silverado and my CUCV M1028 Wrecker. The engine will only overheat once the transmission heats up past 220°. Until that point the radiator keeps the engine where it needs to be. So I install my external coolers before the transmission. This still allows the radiator to warm up cold transmission fluid just prior to it entering the transmission during normal operation.

I operate my trucks in the desert with summer temps near 115° occasionally so my environment is different from yours. You may need to take steps to prevent over cooling in the winter, I just don't know.

I wouldn't install an external cooler if I wasn't experiencing overheating. If it ain't broke, don't fix it.

Good luck.