Planning a trans cooler 04 express 3500

[Sprung Monkey]

Planning a trans cooler 04 express 3500

I towed 3500LBs includes trailer for the first time w/ the 3500 RV van a 200 mile each way trip from 250’ above sea level to 950’

Constant incline not flat then steep inclines.

she did OK but the 03 express 1500 w/ the 5.3 tows much stronger.



The 04 express van has a LQ4/4L80. I’m planning the trans cooler to be external no radiator heating up ATF then cooling down for me.

?1. is the imitation 40K true cool just as good as the real true cool for twice the cost?

?2.is it true or false the inlet/outlets must be either at 12 o/clock from top or from side?

Never feed from underneath?

I think the long 40K won’t fit vertically not sure?



Images of the mounting to rads A/frame an hose routing would help.
here's my plan just by going w/ images.

Thanks for any tips

 

[Mooseman]

I think the mounting with inlet/outlet pointing down is the possibility of air getting trapped. How can they know this is possible unless it was transparent? Of they did testing with a transparent unit? I've mounted mine with them down, no issues AFAIK.

Doesn't your van already come with one from the factory? HD vehicles usually do, albeit on the smaller size. Maybe monitor your temps first unless you really want to be sure you have sufficient cooling.

I think as long as it's not one of those really cheap tube and fin coolers, it's fine.

 

[Sprung Monkey]

I haven't had the grill off or even looked though the grill for a cooler. I just assummed it wouldn't have a cooler. all previous GMs didn't have.
apparently the 3500 doe's in fact have a cooler.
this OEM looks like a B&M super cooler weird it has bottom feeds. and yes what you say thats exactly what I read air being trapped causeing a potensional vapor lock.
I'll take a close look though the grill to confirm it's there an report back.
as for monitoring the trans temps, last time I connected a gauge (on the cars 4L60) was in the trans diagnostic port on the driver side IIRC
excellent advice as usale Mooseman
edit: strange looking trans cooler
which still gets heated fuild from rad.

 

[Mooseman]

You could use an ELM 327 bluetooth adapter with the Torque App. I'm surprised your cluster doesn't have a trans temp gauge but then this is a van, not a truck. Most trucks had them back then.

The cooler in the first pic is the one I've seen the most, maybe smaller on 1500 trucks. The second pic I've never seen. Maybe those are on newer ones. Looks too clean.

They must have learned to not use an in-radiator cooler as my 2021 doesn't have one, just one mounted in front of the rad but it did have a thermostat in the cooler line to get the trans temp up. I eliminated that and it cools all the time.

 

[Sprung Monkey]

I still haven't got the scanner an app plugged into the OBD2 port maybe this time I will.but would be nice to have a gauge on all the time.

I'm doing internal Wix filter

https://www.amazon.com/dp/B000C9TD48/?tag=gmtnation-20

an imitation cooler

https://www.amazon.com/gp/product/B08WS5Y9Z8/?tag=gmtnation-20

also add a external oil filter this https://www.amazon.com/gp/product/B004XONTPM/?tag=gmtnation-20

mounted in direct airflow acts as a 2nd cooler.

when I dropped the 4L60 trans. pan on the car the two bolts that hold the shift linkage cables I was instructed to use red permatex gasket maker on these two bolts threads, is the 4L80 the same?

what do you think of this imitation true cool cooler I link to above

or can you recommend a decent cooler an trans fuild line.

what dex cool trans fuild doe's the 04 model 4L80 use? or is it the latest version I think it's upto dex5.

last time I change trans. fuild on the 97x I removed the trans cooler line an pumped half the fuild out w/ the trans.s pump then dropped the pan.

what is your 021 vehical? thanks

 

[Mooseman]

when I dropped the 4L60 trans. pan on the car the two bolts that hold the shift linkage cables I was instructed to use red permatex gasket maker on these two bolts threads, is the 4L80 the same?

Never heard of that one. I never use any type of RTV anywhere on any tranny.

what do you think of this imitation true cool cooler I link to above

I think it will be fine. Good reviews on it however several said to beware of the hoses that come with it as they fail.

what dex cool trans fuild doe's the 04 model 4L80 use? or is it the latest version I think it's upto dex5.

Dexron VI. It may have originally come with Dexron III but it's NLA, replaced by VI, which is a much better fluid.

last time I change trans. fuild on the 97x I removed the trans cooler line an pumped half the fuild out w/ the trans.s pump then dropped the pan.

That's how I usually do it to reduce mess. In fact, I pump all of it out until it starts to sputter from the line.

what is your 021 vehical? thanks

It's in my signature.
2021 Sierra Elevation 3.0L Duramax with the 10 speed.

Edit: I don't recommend the external filter. I installed one once and it burned up my transmission because it restricted flow.

 

[marcie_chapman38]

Orientation thing — the 'never feed from the bottom' rule is really about air traps more than some hard spec. Inlet near the top so bubbles clear naturally; both ports sitting low and you get dead zones in the core where fluid just sits. Got more on the cooler brand question and Express mounting options here: https://haulandtrail.com/towing-hauling/external-trans-cooler-4l80e-express-3500-trucool-mounting/

 

[BeverlyDay92]

From what I've seen, the imitation ones are a real gamble on a setup like this — there are documented cases of knockoffs splitting under hard tow load, which is exactly the scenario you're describing. Genuine Long-manufactured is what trans rebuilders actually spec, full stop. Went deeper on the orientation rules and the bypass question here: https://haulandtrail.com/towing-hau...ission-cooler-trucool-40k-orientation-bypass/

 

[Sprung Monkey]

here's the 3500 first time I ever continued w/ the rad in series w/ the external.(the RV PPL talked me into to it. probaley won't be doing long distanse towing w/ the 3500.


note the return is on top so to not trap air

edit: the way that artical reads is missleading w/ bottom feed. it should read when both feed an return are on bottom. here's the usale cooler I opt for it's 26K have it on both 3500 an the 1500.

 

[Sprung Monkey]

here's the 1500 I bypassed the rad. will probaly redo the 3500 an bypass rad.used fuel injection clamps again return to trans on top.
having diffaculty adding text after inserting images can't get my cursor back under or after image?

I believe the 1500 w/ it's 5.3 an smaller 4L60 weight around 5750LB will tow stronger than the 3500 w/ the 6.0 an 4L80. she weights 8250LB
so it's like having almost 3K LBs of cargo onto of regular van weight.