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 > Coast on the uphills accelerate on the downhills

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GeoBoy

Bennington

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Posted: 01/11/20 02:16pm Link  |  Quote  |  Print  |  Notify Moderator

BenK maybe on to something with that engine radiator. I installed this in my 2007 3500 with the 4L80E transmission, https://oregonperformancetransmission.com/product/LNG-47391.html. The factory transmission coolers on the 4L80E were marginal at best.

BenK

SF BayArea

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Posted: 01/11/20 05:15pm Link  |  Quote  |  Print  |  Notify Moderator

GeoBoy wrote:

BenK maybe on to something with that engine radiator. I installed this in my 2007 3500 with the 4L80E transmission, https://oregonperformancetransmission.com/product/LNG-47391.html. The factory transmission coolers on the 4L80E were marginal at best.


GeoBoy, that is one of the best types of low PSI, stacked plate radiators out there. Best if the connections between each plate is brazed together and think this vendor does so

[image]

Those which have gaskets, tend to leak over time. More so in dynamic applications with vibration. Solved by brazing the plates together with past filled with brass & heated to fuse them together...they even had upset areas on the plates that touched the other plate to lessen ballooning of flat surfaces in higher PSI applications

OEM stacked plate types are good, but not as good as this type of stacked plate (flattened round tubing)

I'm of the opinion to have as much external aux ATF cooler as you can stuff in. Main caveat is that the ATF must also be plumbed into the engine radiator and in extreme cold, a by-pass to remove the external aux cooler

'Was' going to install a larger external, aux ATF when still owned the 8.5K lb boat + trailer and my 7.4L continued to get hotter and hotter while towing. Until it also heated up just commuting to work (32 mile one way, Silicon Valley can get really hot during the summer and fall), which meant something else was wrong

Installed a severe duty fan clutch thinking it was going bad. Instantly cooled it down for a while, but then it started to get too hot again.

Turned out to be plugged radiator from DeathCool (Dexcool and coined it because almost lost the 7.4L). Had the OEM radiator rebuilt (new plastic tanks and rod'ed out the core). Still have the modified 180*F thermostat in there...think it's #3

Then never needed the bigger external aux ATF cooler. Will do so when I rebuild the 1996 Suburban. As the 7.4L will be 'built' and other goodies that will increase the BTU's to be rejected


-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

opnspaces

San Diego Ca

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Posted: 01/11/20 08:59pm Link  |  Quote  |  Print  |  Notify Moderator

I found a GM publication called the 2001 Chevrolet Suburban Restoration Kit. Unfortunately the way I read it there is only lockup in 4th. So I guess I would have to look into an aftermarket lockup if I wanted to lock up in 3.
[image]

And the link to the manual
Link


2001 Suburban 4x4. 6.0L, 4.10 3/4 ton
2005 Jayco Jay Flight 27BH
1986 Coleman Columbia Popup.

opnspaces

San Diego Ca

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Posted: 01/11/20 09:07pm Link  |  Quote  |  Print  |  Notify Moderator

I have a question about transmission temp for any of you running a similar age range truck or Suburban.

When I am running unloaded, just soccer dading around the city my trans gauge is just shy of 200. I thought that was normal since the radiator is 195. But after reading into many of the posts I'm wondering if I'm already too hot? What are you guys seeing for normal unloaded transmission temps?

drsteve

Michigan

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Posted: 01/12/20 11:21am Link  |  Quote  |  Print  |  Notify Moderator

My 06 with 4L80E runs cooler when I leave it in D and tow haul. Selecting 3rd always makes it run a bit warmer, even on flat roads. Temp is usually around 185 or 190 towing, very seldom goes over 200. Unloaded it stays around 160-170 ish.

I have never noticed the TC locking in 3rd.


2006 Silverado 1500HD Crew Cab 2WD 6.0L 3.73 8600 GVWR
2018 Coachmen Catalina Legacy Edition 223RBS
1991 Palomino Filly PUP

SweetLou

La Quinta, CA USA

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Posted: 01/14/20 07:08am Link  |  Quote  |  Print  |  Notify Moderator

While most are commenting to you about the equipment possibilities or things to check, I wanted to let you know that they way you drive while towing is also very important. I am on my third Dodge (now Ram) a 2013 diesel 6.7 with the 68FE trans.
From previous set up, I had exhaust temp guage which goes hand in hand with radiator temp. In order to keep the truck temp cooler I had to balance the exhaust temp and boost from the turbo. I rant the temp at around 1000 to 1100 which and of course using the correct gear to maintain RPM. It's a balancing act and it kept the radiator cooler, thus the trans cooler as well. If I ever put my foot into it, the temps shot up, so I learned to cut back. I am pulling, not racing and it chugs up all the way. Try the 16 mile Baker grade near las Vegas on 116 degree day pulling anything with never a hiccup. So, my advice also to find your sweet spot learn that pull truck and you will be fine.


2013 3500 Cummins 6.7 Quadcab 4x4 3.73 68FE Trans, 2007 HitchHiker Discover America 329 RSB
We love our Westie


BenK

SF BayArea

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Posted: 01/14/20 11:33am Link  |  Quote  |  Print  |  Notify Moderator

SweetLou is correct, but mainly for a forced fed ICE.

Meaning the pedal (diesel's do NOT have a throttle plate) can force more than the listed displacement specification. A 6.7L can become a 8L/10L/etc...until it produces so many BTU's via more fuel injected, that the surface area of the thermal rejection system can NOT move those extra BTU's away fast enough to whatever rejection system component it has...that the metal will raise to glow, then melt

On a N/A ICE, it can ingest a bit over the displacement specification via inertia ramming...AKA scavenging effect

There are many other attributes that contribute to the BTU development of an ICE, but the above are the basic's

If you wish to delve deeper into this area, here are the 2012 GM 6.0L L29 torque/HP curves just found for this discussion. They are from the GMPowerTrain site. Mechanically, these L96's are the same. The main difference is in the state of tune. There would be differences in the thermal rejection components and sub-systems



This is for half ton pickups with L96 6.0L
[image]


This for HD pickups with L96 6.0L
[image]


This for 2500 Suburban with L96 6.0L.
[image]


This is for Express/Savanna 2500/3500 full sized vans with L96 6.0L
[image]

As a general rule of thumb, the best MPG while towing heavy is to choose an RPM just below to at peak torque. Going over that RPM will gain HP (torque x RPM / 5252), but cost MPG's and produce more BTU's

Figure what HP you desire to tow heavy at and then choose the gear that keeps your 6.0L in that range

opnspaces

San Diego Ca

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Posted: 01/15/20 08:14am Link  |  Quote  |  Print  |  Notify Moderator

Thanks Ben. I've been messing with this truck for a bit and I found something that to me is interesting. This is when I drive unloaded as in no trailer and only me in the truck. If I drive the freeways the temperature stays low around 160. But if I drive around town with all stop and go traffic lights, the temp climbs to almost 200 and stays there. So to me this means either my fan clutch is going, or my radiator has no real cooler built in. I think my first and cheapest move it to pull the lower coolant hose and see if I can find a way to look in the tank at the cooler.

opnspaces

San Diego Ca

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Posted: 01/15/20 08:18am Link  |  Quote  |  Print  |  Notify Moderator

Also I pulled the trailer back to storage and temperatures were better than last week. First thing I did was I pulled in D not 3rd to try to stay in lockup as much as possible. Of course when I hit the hill the truck forced a downshift to third. I held the RPM's at 4,000 except at points where I had to lift my foot to avoid rear ending the slow soccer mom in front of me and dropped to about 3800 RPM. The temperature gauge was much better and didn't even hit 200 on the hill though it did slowly climb there as I drove. So it was better, but I'm not out of the woods yet. below are a few things that probably contributed the differences.

First, I will admit I was distracted with general life issues and forgot to turn on tow haul. I'm seeing this as a negative and will definitely make sure it's on for the next pull.

Second, I was pulling the trailer empty as I was headed to storage.

Third, the pull was only about 20 miles. If I had to go further I'm sure the heat would have climbed.

BenK

SF BayArea

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Posted: 01/15/20 10:53am Link  |  Quote  |  Print  |  Notify Moderator

Your latest info says to me, that air flow is the main issue. Highway will have much more air flow than stop and go...where the fan is the key to keeping air flow up there

Even if you have an El Cheapo radiator, running with just the driver, it should not behave like that...heating up in stop n go, as you still have the external aux ATF cooler

Since a 2500, EVERYTHING is sized for HD usage. Thermal abilities are one of the main attributes making your truck a HD towing vehicle. The margins (head room) are there to absorb that kind of short term usage needing more HP in spurts (acceleration from a stop)

Hope that is all there is, but you never know until the situation is completely fixed.

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