Here is the stock towing test: kzfaq.info/get/bejne/rZt7dN2bvrG6cYU.html

My girlfriend overheard you talking and said upgrading from 3.25" and less than half an inch to 6.75" and 2"+ inches would be indeed a nice so I'm ordering a new Pee PeE piece even though I do not own a truck.

Just my two cents. I have a 2023 LTZ with the 3.0 LZO. My experience is that once up to full operating temp my transmissions temperature hovers around 200°F +/- 5°F no matter if I am loaded, unloaded, highway, city, low ambient, or high ambient temp. That tells me that these transmissions are thermostatically controlled. So adding a larger trans cooler is not going to lower transmission temps in this towing example. The larger cooler will only play a factor once the limitations of the factory cooler are exceeded. Being an Engineer myself I feel confident that the Engineers at GM took the max towing rating at an extreme ambient temp, and grade when sizing the factory cooler. Like you mentioned it may be good insurance for the ones that are towing often at the weight limits in areas like west Texas, but those people probably bought 2500's not 1500's.

Very cool video on the trans cooler . Great job showing all the details . It shows it improves the cooling of the trans overall .

Many years ago, long before PPE started making OEM style upgraded transmission coolers, there was a guy (Mike L was what everyone knew him as on the Duramax Forums) that worked at Inglewood Transmissions, presumably in Inglewood, CA. He sold upgraded OEM style coolers for the Allison 1000. Everyone called it the "Mike L trans cooler" I installed one and it made a significant difference in trans temps on my 2009 3500HD 6.6L / Allison. It was pretty similar to your new cooler, total bolt on in place of the factory wimpy cooler.

Great video! In my Lexus GX460, the two horns are placed directly in front of the rad. I actually moved them down behind the bumper support (which already blocks airflow), and afterward noticed that my cooling fans run much less under the same conditions. You might be able to bend that horn bracket so that the inner horn module doesn't block as much airflow. Love these vids! Great work!!!

You're supposed to add transmission fluid after installation. Add the remaining ounces the new cooler has over the old one.

Hey Tim, Thanks for the look at installing the PPE and how it performed. Seems like from what you’ve shown here and prev, that trans fluid flow may be held until temp reaches near 200F. That temp reached 205 before but stayed steady near 200 suggests the PPE CAN dump all of the heat from the trans even while towing the RV on your test hill. So you’ve still got available cooling capacity with the PPE where the stock cooler was not quite keeping up. good deal!!

Thanks for the tech video! Very few (if any) KZfaq automotive folks work on their own vehicles. This is what makes your channel stand out above the others. It's cool to see what's involved getting the grille taken apart and put back together.

I like these install videos of you doing mods on your trucks. Wish you could do more of them. But I understand you only have them for 1 year, so you don't really want to mod them too much.

I live at 7500’ but to get supplies I have to travel from a valley at 4000’ over a ridge at 9000’. With a somewhat empty truck (‘23 GMC SIERRA LZ0) transmission temp was 183 at 4000’ (71 deg ambient) and 199 deg at 9000’ (58 deg Ambient) over a distance of 16 miles (3.23 rear axle). Not towing.

There is a thermostatic control valve that regulates the fluid flow in the trans to maintain temperature at 200F. you can see that 200 is just about dead center of the gauge temperature. There are other videos of people bypassing or removing the control valve to allow full flow and cooling of the trans cooler.

Its not an exact science experiment as you pointed out with the warmer ambient temperature but I was wondering if the engine coolant max temperature was any warmer then the day before. Definitely anything that adds heat in front of the engine coolant rad or covers more area of it would be a possible negative to its cooling performance. A more drastic example are vehicles from years back that could be purchased with or without air conditioning and so therefore the non air con vehicle had no condenser in front of the coolant rad to hinder air flow and of course in any vehicle when using the air con, it rejects heat causing the engines radiator to not be as capable to cool the engine, why in Death Valley the sign at the bottom of the steep grade out of the valley says "Turn your Air Conditioning Off". Without a doubt the general theme has been that 1/2 ton pickups had a thinner coolant radiator then a 3/4 or 1 ton but also the fan blades were far deeper on the heavier pickups and could move a lot more air and it used to be that the same engines were being used in both light and heavy pickups, the only difference was the whole cooling package was more capable.

These trucks have a 190 degree thermostat, no matter how efficient the cooler is the thermostat will keep it around 190. They make thermostat kits so that you can reduce the temperature to 150-160.

Did you have to top up the trans fluid? I'd think you were down at least a quart by adding this cooler upgrade. Great job though, you can never have too much cooling, especially on a tow vehicle Curious question, what's the difference in highway cruising RPM vs max towing package with 3.73 axle ratios? I've been considering an elevation with the max tow but mainly want it for the stiffer leaf packs since I'm constantly varying a few hundred pounds in tools and material. I'm more concerned about the added noise from the higher rpm and the added fuel

When you did your tests - did you account for the outside air temp (OAT) on each test? That's really what will help you measure your transmission cooler efficiency. The delta between your OAT and trans temp is what you want to measure. I installed a larger cooler on my 09 Tahoe and dropped the delta to about 50 degrees from OAT at highway speeds, or 80 degrees delta from OAT while towing. So, if it's 100 degrees OAT out, the highest I see on straight and level while towing is 180. I also have a 24 Silverado 2500HD - I'm thinking about the PPE trans cooler for that. But don't know if I will see that much of an improvement.

Is your truck a max tow package? The trailer you were towing , do you have a weight of the trailer

My 23 LZ0 has the max tow package. I wonder if this cooler is much of an upgrade?

is it a 3.23 rear diff or 3.73? cant seem to fine the option for the 3.73.

You probably should check/top off the trans fluid. Not only did you loose what was in the old cooler. But your new bigger cooler will eat up more system volume as well. Probably not low enough to be catastrophic or anything. But still a brand new truck and all. You don’t wanna be driving around low on ATF for the next 30k or whatever the service interval is.

I asked my dealer about the fuel pump issue a few years ago. His response was they hadn’t seen any duramax diesels come in because of the fuel pumps exploding. Yet you don’t have to search very hard to find horror stories from owners where the pump exploded. This really stinks-and GM should be held liable for replacement cost.

Do you know if the ppe trans cooler will affect the warranty

Bad boy! Only a GM certified mechanic can install the water line to the front camera. Was that T-15 an approved GM tool!

did u add extra trans fluid to fill the volume of that much bigger cooler?

lol @11:28 "I didn't have any problems, you shouldn't either"

Thinking of doing this same upgrade on my Lm2... Just curious about transmission fluid - did you need to add any? What happened to the excess fluid that was in the original cooler? Did you lose any on the swap, or need to add some after?

What this truck reallywhat this truck really needs is a proper intercooler, the in/out temp of the top mounted intercooler is marginally impacted at best.

Gonna be honest off the bat, only watched the results. But did you remove the thermostat device that controls when the oil cooler is used? New trucks have them where they only use the cooler at certain temps. This could be why there was little change. I recommend if you didn’t that you and retest with both stock and aftermarket

I like how people say: "blah blah OEM engineers did the research and you dont need that" But when it supports their bias: "idiot engineers, cost cutting accounting dept, planned obsolescence blah blah"

When towing do the shutters stay open? I say this because they wouldn't help the cooler's performance if they are closed. Maybe they work following engine temperature and not transmission temperature.

You're like a firehose of information this week. That's a bit of effort and coinage if you're not having any issues IMO. TBH, manufacturers have gotten pretty good about their towing claims in recent years provided you comply with any restrictions/recommendations. Then again, I operate at sea level with mostly flat terrain so maybe Western folks don't experience the same.

I put the PPE Trans cooler, thermostat bypass, and +4 quart trans pan on my 21 AT4 3.0 It never goes over 170deg F no matter how hard I run it towing my 7000lb rockwood.

I wonder if the temps would be down if you topped it off for the larger capacity?

Did you have to add any trans fluid with the bigger cooler?

How much extra trans fluid did you have to put in for this mod?

Hey Tim, Nice DYI trans cooler upgrade and test drive! Does this cooler exchange require pre filling the new unit with correct ATF and or can there be an issue with not burping the air out of the system per instructions? Last but not least. Thanks for not making the latest issue of “ Plummers crack exposed “ on KZfaq video! ;) As always stay safe and healthy! Ron

It's been a month since this video. Did you install the PPE thermal bypass? did you top up the trans fluid? People want to know!

Did you add back any transmission fluid after the change? How much fluid do you think you lost when removing the old one? With the larger radiator I imagine it would hold a little more. Should there be any worries about adding air to the lines when installing?

May have introduced air bubbles into the cooling system maybe ask gm

Those louvers as you called them are shutters. Over the road diesel engines had those back in the 50s,60, 70s and early 80s then they were phased out by better control over the cooling system

I would think Chevy installs a big enough cooler/radiator that will work just fine. Changing your transmission fluid and filter often matters most.

That should help. How long did it take you?

Awesome video. You should swap in the PPE thermal bypass valve to completely delete the ATF thermostat. PPE doesn't tell you that but you really won't see any temp improvement with that cooler unless you allow constant free flow through it. I have the PPE deep trans pan paired with the thermal bypass valve and stock cooler on my 2023 LZ0 Trail Boss, trans temp never goes over 175.

Did you add more transmission fluid to fill the void caused by adding the transmission cooler?

The popular question seems to be "did you add more transmission fluid"?

By adding the new cooler, did you need to add transmission fluid? If so, how much?

GM uses those air flaps in the grill to force high temperatures. They want the water and transmission fluid to run hot. They deliberately drive oil and rad temperatures high to help with fuel mileage.

Did you put atf back in it???

Does this void the warranty?

This does what to the warranty ? Thanks

You don’t want your transmission to run cold because it will lower fuel mileage. That said, the new cooler won’t lower temperature if the louvers are closed, so you might want to check the conditions to make those open.

Bigger transmission cooler blocks the radiator more and could make the engine radiator work harder because it's getting less airflow. This upgrade seems unnecessary and probably voids the trucks warranty.

How much fluid did you have to add to the system after changing the cooler??