cjm1973

Came across this GMA news bulletin recently which confirms the loss of the transmission oil coolers in future production runs. Glad I have one as well as an additional cooler I installed in-line of the OEM. Temps have never exceeded 195, even in 90+ degree weather towing 7600lbs of trailer up a mountain grade. Don't know how the new vans' transmissions will hold up when taxed.

https://gmauthority.com/blog/2021/05...on-oil-cooler/

Gumby22

From the article...



To me, this indicates the secondary cooler that’s mounted in front of the condenser is what’s being removed, but the primary cooler (part of the radiator assembly) is still being used.

cjm1973

My thoughts too. Unfortunately, any HD vehicle towing anything significant requires an auxillary trans cooler. I'm just glad my van has two.

William Kisselstein

The one in the radiator tank also serves as a heater, as the fluid has an operating temperature range.

GatorHawk24

Well, they have to remove it as standard equipment so they can make it an option and charge you double...

Gumby22

I don’t know about the vans for sure, but most of the late model trucks (since 2014/2015 models) I’ve been seeing have a thermal expansion valve where the cooler lines bolt on to the transmission. It doesn’t even open to allow cooler flow until the fluid reaches 180*F - 190*F, so while the vans without a valve would utilize the radiator as a heater and a cooler, the vehicles with a valve would only be utilizing it as a cooler.

The trucks that don’t have the expansion valve are equipped with the secondary cooler. I don’t know what the RPO code is, but when reading GM service information, they define the dual cooler set up as “HD cooling.”

pomerlo

Ironic ... I installed an aftermarket one for my 4L80 on my 2004 3500 last weekend

mountainmanjoe

I think that's called coincidence, not irony.

But anyway, they're probably doing this to meet stricter fuel consumption laws. Same reason they started building bypass valves into water pumps.

mountainmanjoe

I thought thermal expansion valves were for systems where you have gas-liquid phase transitions. (like AC refrigerant). If a valve is simply actuated by temperature then isn't that just a thermostat? (like the coolant loop)

Gumby22

That’s technically accurate, I just tend to think of them in the same terms, because the cooler line thermostat operation is very similar to an expansion valve.

An expansion valve creates a reduction in pressure and allows expansion of the refrigerant to occur - since pressure and temperature are directly proportional, as the pressure drops, so does the temperature. The diaphragm in the TXV reacts to the change in temperature and the size of the orifice increases and decreases accordingly.

The cooler line thermostat doesn’t change the pressure but it regulates flow through the cooler based on changes in temperature, so the valve inside the thermostat is also opening and closing in the same way as a TXV.

I replace the cooler lines with the thermostat on them quite a bit - next time I do, I’ll try to remember to save the valve and take some pictures - the design (internal and external) of the thermostat and block type TXV are very similar.