2018 Silverado 1500 External Transmission Cooler?

BillNC · August 10, 2018

I am trying to determine if the new 2018 Silverado Crew 1500 that we just bought for towing a horse trailer has:

(1) A transmission fluid cooler that is an integral part of the radiator, AND

(2) An auxiliary transmission cooler that is located in the top of the AC condenser.

Based on the Build Report and the GM Order Guide, and the thread I found here from 2014 or 2015, I believe that the truck has both the items above. But the service manager just emailed me back and said that the truck does not have (1) but does have (2).

Build Report reads: "KNP - Transmission Oil Cooler"

http://gmauthority.com/blog/wp-content/uploads/2017/06/2018-Chevrolet-Silverado-1500-SSV-Order-Guide.pdf

The info below is cut and pasted from the above GM document.

"KC4 Cooling, external engine oil cooler S S"

"KNP Cooling, auxiliary external transmission oil cooler S S"

"L83 Engine, 5.3L EcoTec3 V8 with Active Fuel Management, Direct Injection and Variable

Valve Timing, includes aluminum block construction (355 hp [265 kW] @ 5600 rpm,

383 lb-ft of torque [518 Nm] @ 4100 rpm; more than 300 lb-ft of torque from 2000 to

5600 rpm)"

Your help sorting this out would be greatly appreciated,

Thanks,

BillNC

Jon A · August 10, 2018

Shine a flashlight in and look at the condenser. If the top 7-8 rows have thicker plates than the rest, that's the external air/oil tranny cooler. You can also trace the lines to that area (one goes in on one side, one comes out the other side). Your 5.3 should have it.

mjm-1957 · August 10, 2018

Why would you buy a 1500 to tow a horse trailer?You should have stepped up and got a real truck,2500 or 3500.

BillNC · August 10, 2018

26 minutes ago, Jon A said:

Shine a flashlight in and look at the condenser. If the top 7-8 rows have thicker plates than the rest, that's the external air/oil tranny cooler. You can also trace the lines to that area (one goes in on one side, one comes out the other side). Your 5.3 should have it.

Thanks. I'll do that. Was the service manager right when she said that the truck did not also have a transmission cooler built into the radiator?

Jon A · August 11, 2018

No, your truck should have both. The fluid line from the tranny goes to the radiator tank on the driver's side, back out the radiator tank on the driver's side and into the A/C condenser also on the driver's side. It then goes out of the A/C condenser on the pass side and back to the tranny.

Jon A · August 11, 2018

3 hours ago, mjm-1957 said:

Why would you buy a 1500 to tow a horse trailer?You should have stepped up and got a real truck,2500 or 3500.

Why assume he needs a 2500 before you know how big the trailer is? For all you know it's a tiny single-horse....

Mine does just fine up to four horses:

For a trailer like the brown one, of course:

Then yes, wrong tool for the job.

BillNC · August 11, 2018

10 hours ago, Jon A said:

Why assume he needs a 2500 before you know how big the trailer is? For all you know it's a tiny single-horse....

Mine does just fine up to four horses:

For a trailer like the brown one, of course:

Then yes, wrong tool for the job.

Two horse with dressing room. 5,850 lbs with one warmblood. Load equalizing hitch. Absolute max that would ever be towed would be 7,500 lbs. Truck is rated for 9,300 lbs. My wife towed this same trailer for 12 years with a F-150 rated at 8,500 lbs.

Edited August 11, 2018 by BillNC

BillNC · August 11, 2018

10 hours ago, Jon A said:

No, your truck should have both. The fluid line from the tranny goes to the radiator tank on the driver's side, back out the radiator tank on the driver's side and into the A/C condenser also on the driver's side. It then goes out of the A/C condenser on the pass side and back to the tranny.

I was thinking it should have both too.

Looking through the grill, I did not see thicker plates at the top of the condenser.

I've crawled under the truck and traced the engine oil lines and the transmission fluid lines. (Also wiped the oil off the bottom of the oil filter and tightened it by hand.)

Engine oil lines run down the left side of the engine and tie into the radiator high and low on the right side.

Freon lines tie into the condenser on the right side. Condenser appears to be the same size as the radiators.

Transmission fluid lines run down the right side of the engine and tie into the right side of the condenser high, and the left side of the condenser high.

I double checked this as best I could and I think the above is accurate. It's hard to see around all the cowling, etc.

The engine oil is routed through the radiator. Maybe the condenser was upsized???

I'm going to ask the dealer for a link to an exploded parts diagram for my truck as built.

Many thanks!

Edited August 11, 2018 by BillNC

Jon A · August 11, 2018

That's interesting. If there are no lines going into the driver's side radiator tank then there must not be a heat exchanger there. I wonder if they eliminated it on newer models? If so, that's a good thing IMHO. It was a dumb design to begin with as that's the hot tank of the radiator and will act as a heater instead of a cooler about 95% of the time anyway. I have seen people with the newest trucks report cooler trans temps when towing than mine could ever maintain when stock, maybe that's the reason. I'm currently running with mine bypassed and like it better that way, so if your truck doesn't have that don't worry about it, it's no big loss.

If you've traced the lines to the condenser, you definitely have the air/oil cooler, which is the important one so you should be good to go. Seeing the thicker plates (the part of the rows between the fins) is subtle, and not easy to notice unless you know what you're looking for.

BillNC · August 12, 2018

The top 7 horizontal bars in the condenser are thicker than the ones below. Missed that before.

Thanks again.

BillNC · August 13, 2018

2018 Silverado 1500 Engine Oil Cooler Lines.pdf

2018 Silverado Transmission Fluid Cooler Lines.pdf

Over the weekend I visited gmpartsguys.com (they are also a dealership) to look for a GM auxiliary transmission cooler for our truck. I could not find one, so I emailed them the VIN number and the Build Sheet info. They just called me back and told me that I already had an auxiliary transmission fluid cooler. I explained that these parts drawings showed otherwise. He said he would call GM and then call me back.

He called back and told me that GM said: My truck is not built with an auxiliary transmission cooler, and none are available.

Kudos to gmpartsguys!

Edited August 13, 2018 by BillNC

Jon A · August 13, 2018

On 8/12/2018 at 5:17 AM, BillNC said:

The top 7 horizontal bars in the condenser are thicker than the ones below. Missed that before.

Yup, that IS your auxiliary cooler. It's actually quite big for a 1500. You have the best transmission cooling available on these trucks. You'll be fine. If you find you want even cooler temps, bypassing/replacing the thermostat with an aftermarket unit makes a big difference and tuning the fans to come on earlier helps as well, especially at low speeds but I doubt you'll find any of that necessary with a trailer that size. Is most of your towing on the highway or is a lot of it on slow gravel roads, etc?

Thanks for posting that parts diagram. I did not know they did that. It's likely the main reason some users of newer trucks have reported better performance (cooler transmission temps) than the older ones. If I had posted my rants on how dumb it was for GM to put an in-tank heat exchanger in the hot side of the radiator a couple of years ago, I might accuse GM of listening to me. Again, so there's no confusion, it's no loss. I have mine bypassed and the trans runs cooler for it. In all but very rare conditions, that radiator tank exchanger acts as a heater, not a cooler. And since we have a thermostat, the heating function is worthless at warmup anyway making it pretty much worthless all the time.

Doublebase · August 13, 2018

Wait a second...GM uses the upper portion of the condenser as the transmission cooler and the side tank of the radiator as the oil cooler? I don't think I've ever heard of a setup like this. Did GM ever do this before 2014?

Jon A · August 14, 2018

Yes. 2014 is the first year as far as I know, at least with the trucks. If interested in the science behind it, SAE-2003-01-0529 ( https://www.sae.org/publications/technical-papers/content/2003-01-0529/ ) has good analysis/test results. In short, using a combo cooler is a more efficient way of doing it. Placing the transmission cooler in front of the condenser adversely impacts A/C performance, so manufacturers tend to make them small on light duty vehicles which will obviously affect transmission cooling performance. This way, you end up with a trans cooler that's something like 5"X26" which is pretty huge for a 1/2 ton and it doesn't kill the A/C.

Edited August 14, 2018 by Jon A

BillNC · August 14, 2018

Jon, thanks for your help with this! My wife will be turning the transmission temp display on every time she tows. All blacktop. No mountains. Occasional trip from NC to Fla on I-95. She towed on back roads yesterday, about 12 miles each way and the highest temp was 197.

How does one tune the cooling fans?

Mike, the sales manager investigated the build a truck tool for the 2018 Silverado 1500. Apparently the transmission cooler in the condenser and the engine oil cooler in the radiator comes along with the 5.3 engine. If you look at the parts listings that I posted, it shows the same parts for 2017 and 2018.