Correct Tru-Cool 40k Trans cooler

[DaveO9]

I bought the Tru-Cool Max LPD 47391 trans cooler, without thermal bypass. Hindsight, I'm thinking I should have bought the 4739 with bypass? I live in Vancouver, WA (weather same as Portland, OR) but I do use it for some cold weather / snow activities. Should I send the 47391 one back and get the 4739?

One I bought: https://www.amazon.com/dp/B0060NKA1U?psc=1&ref=ppx_yo2ov_dt_b_product_details

One I think I should have bought: https://www.amazon.com/Tru-Cool-LPD...mzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

Why are they the same price? Shouldn't the thermal bypass one be more expensive. Or is there some other difference besides the bypass. Dana vs Long?

A general trans cooler question or two:

- I had planned to route the cooler in series, after the in-radiator trans cooler. (no aux cooler on my Tahoe) but the instructions make it sound like it's preferred to bypass the OEM radiator cooler. Thoughts?

- I've seen other posts on here with concern about the big Tru-cool blocking too much of the radiator and increasing engine coolant temp. What's the latest consensus on that?

 

[Geotrash]

I bought the Tru-Cool Max LPD 47391 trans cooler, without thermal bypass. Hindsight, I'm thinking I should have bought the 4739 with bypass? I live in Vancouver, WA (weather same as Portland, OR) but I do use it for some cold weather / snow activities. Should I send the 47391 one back and get the 4739?

One I bought: https://www.amazon.com/dp/B0060NKA1U?psc=1&ref=ppx_yo2ov_dt_b_product_details

One I think I should have bought: https://www.amazon.com/Tru-Cool-LPD4739-4739-Pressure-Transmission/dp/B00803CTDA/ref=sr_1_2?crid=17CDS1C6HHOZ7&keywords=tru+cool+thermal+bypass&qid=1698815707&sprefix=tru-cool+thermal,aps,170&sr=8-2&ufe=app_do:amzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

Why are they the same price? Shouldn't the thermal bypass one be more expensive. Or is there some other difference besides the bypass. Dana vs Long?

A general trans cooler question or two:

- I had planned to route the cooler in series, after the in-radiator trans cooler. (no aux cooler on my Tahoe) but the instructions make it sound like it's preferred to bypass the OEM radiator cooler. Thoughts?

- I've seen other posts on here with concern about the big Tru-cool blocking too much of the radiator and increasing engine coolant temp. What's the latest consensus on that?

Towing heavy in hot weather is the only time that the radiator blockage that the 40K creates is a problem - and mainly on the 6.2L because it generates more heat into the same cooling system as the 5.3.

But to your main question, I don't see a thermal bypass in the pics. So I'm skeptical about what exactly they're referring to. Is it a thermal valve that opens to direct fluid to the cooler at a certain temp? If so, where is it mounted and what temperature is it set for?

I have a Trucool 40K on my '07 and I don't tow with it because of the aforementioned problems. I don't care for it either because it's near impossible to get the fluid temp up to 150ºF even in the summer, which is what GM says is the minimum operating fluid temp they want to see. I have a Derale 13960 on my 2012 that I tow with and it's the perfect cooler for these rigs in my opinion. It has a fan and a thermostat that turns the fan on at 190ºF, but the only time I see that is when towing. The rest of the time it holds it between 160 and 180 in normal driving without the fan switching on.

 

[DaveO9]

Towing heavy in hot weather is the only time that the radiator blockage that the 40K creates is a problem - and mainly on the 6.2L because it generates more heat into the same cooling system as the 5.3.

But to your main question, I don't see a thermal bypass in the pics. So I'm skeptical about what exactly they're referring to. Is it a thermal valve that opens to direct fluid to the cooler at a certain temp? If so, where is it mounted and what temperature is it set for?

I have a Trucool 40K on my '07 and I don't tow with it because of the aforementioned problems. I don't care for it either because it's near impossible to get the fluid temp up to 150ºF even in the summer, which is what GM says is the minimum operating fluid temp they want to see. I have a Derale 13960 on my 2012 that I tow with and it's the perfect cooler for these rigs in my opinion. It has a fan and a thermostat that turns the fan on at 190ºF, but the only time I see that is when towing. The rest of the time it holds it between 160 and 180 in normal driving without the fan switching on.

Thanks, Dave. Yeah I saw the thread where you added the Derale. Did you end up mounting it at the lower grille on your Yukon? Tahoes don't have that grille, so where would the recommended mounting location be for mine?

I still may just go with the Tru-Cool after making sure it does have an appropriate bypass. I'm going to talk it over with the trans shop that's going to do a pan-drop on it.

 

[Geotrash]

Thanks, Dave. Yeah I saw the thread where you added the Derale. Did you end up mounting it at the lower grille on your Yukon? Tahoes don't have that grille, so where would the recommended mounting location be for mine?

I still may just go with the Tru-Cool after making sure it does have an appropriate bypass. I'm going to talk it over with the trans shop that's going to do a pan-drop on it.

Let me ask a fundamental question first: does your truck have a factory transmission cooler? If so, I wouldn't bother installing a new one unless you're going to do some heavy towing. The factory setup is perfectly matched to the needs of the transmission in that truck. If I had it to do over again in my '07, I would have left it well enough alone. With the Trucool 40K, I actually lost utility because it causes engine temps to rise when towing so I can't tow with it anymore.

But to answer your question, there are folks here who found places to mount it. Given that it has a fan, you can mount it pert near anywhere you want. One guy with a Suburban mounted it off to the side of the radiator.

 

[gooffeyguy]

The thermal bypass isn't a valve, but a reduction in the size of the passages that the fluid runs through. They say that when the fluid it cold it's too thick to run through the smaller passages and will bypass most of the cooling fins. Once the fluid warms up it thins out and will run through all the passages.

 

[DaveO9]

Let me ask a fundamental question first: does your truck have a factory transmission cooler? If so, I wouldn't bother installing a new one unless you're going to do some heavy towing. The factory setup is perfectly matched to the needs of the transmission in that truck. If I had it to do over again in my '07, I would have left it well enough alone. With the Trucool 40K, I actually lost utility because it causes engine temps to rise when towing so I can't tow with it anymore.

But to answer your question, there are folks here who found places to mount it. Given that it has a fan, you can mount it pert near anywhere you want. One guy with a Suburban mounted it off to the side of the radiator.

No, my Tahoe started out life as a rental car: no aux trans cooler, no oil cooler, single-speed t-case, and 3.08 gears. :-( I plan to rectify all of those eventually, but some, especially axles will take a while. Starting with the t-case, have all the parts now. Then aux trans cooler. I've pretty much made my decision to return the tru-cool and wait till spring to add a cooler. Maybe I'll just go with an OEM. I don't tow heavy, but plan to get a travel trailer sometime in the next few years. (not insane, though) My '09 Tahoe had all the stuff listed above, and it's trans would heat up in to the 215 range pulling just over 2k lbs. I haven't towed with the '13 yet, but I definitely want at least an OEM aux cooler. Thanks for input!

The thermal bypass isn't a valve, but a reduction in the size of the passages that the fluid runs through. They say that when the fluid it cold it's too thick to run through the smaller passages and will bypass most of the cooling fins. Once the fluid warms up it thins out and will run through all the passages.

Ah, that explains it. Thank you.

 

[Foggy]

Exactly as Goofeyguy said above... I've been running a cooler in my C1500
for years that bypassed some of the cooling fins if the fluid is too cool... Great
system esp if you ever drive in cool weather

 

[Doubeleive]

the bypass can be purchased seperately you do not have to return what you already purchased

 

[blackelky]

Can we add the factory optioned cooler without too much drama?

 

[Matthew Jeschke]

I bought the trucool bypass regrettably. It's a barb fitting to be used with ring clamp and rubber hose. Kind of chinsy. Got rid of that thermostat and ordered a Derale which uses screw fittings to connect to line set, much better and same price... although not including cost of fittings and adapters.

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