Towing with 97 GMC 6.5 Diesel

[L3700SU]

I've been towing over a 1200 ft (mountain) pulling my tractor L3700 and SG attach for a couple years. I have an older GMC 1 ton dump truck (8k#) and the trailer and my old tractor was totaled about (6.5k#). Over heating was a problem from the beginning so I invested in a Heath cooling upgrade which consisted of a midsize truck clutch fan and a high pressure, high volume water pump. That kept me usually under 210F the entire climb. When I bought the MX tractor, the tow weight increase and so did the temperature again.
I did a little research and added a water/methanol injection system and problem solved. Not only does it keep the truck cool but I can feel the extra power going up the mountain. I've also read it cleans carbon deposits in the engine and increases mileage.
There was some negative comments in some forums but I think that was pretty much bologna as just about anyone running competitive diesel engines use this method to keep them cool.
I think it is a win, win!

 

[North Idaho Wolfman]

This is no knock on you at all, I just found it funny, as that kind of a climb is a day in and day out event up here for most.
My land is a 500' difference from top to bottom, and that's considered fairly flat.

I've been towing over a 1200 ft (mountain)

That engine is know for cooling issues, and every little variable will make it worse.

Sounds like you've tried everything that I've read on them to get them to run cooler.

 

[L3700SU]

This is no knock on you at all, I just found it funny, as that kind of a climb is a day in and day out event up here for most.
My land is a 500' difference from top to bottom, and that's considered fairly flat.



That engine is know for cooling issues, and every little variable will make it worse.

Sounds like you've tried everything that I've read on them to get them to run cooler.

That's why I put parentheses around mountain because in the west, northwest it would barely be a foothill. LOL!

Yea, I had no idea when I bought it, it had that kind of issue towing. I'm told if you keep it cool, it is actually a decent motor. I'm the only one to tow with it as it had no hitch or hitch plate when I bought it and only had 70k on it.
I think I have a pretty sound setup now. I'm very happy with the way it is running.

Thanks for posting!

 

[North Idaho Wolfman]

One other mod is if you have room a pair of electric pusher fans on the front of the condenser really helps too.

The only other changes to the system I see noted are to install of dual thermostats, but I don't know how expensive or involved that mod is.

Is it a manual or automatic?

 

[L3700SU]

One other note is if you have room a pair of electric pusher fans on the front of the condenser really help too.

The only other changes to the system I see noted are to install of dual thermostats, but I don't know how expensive or involved that mod is.

Is it a manual or automatic?

It's an auto. It's already got dual thermos although Heath found the single system force more coolant through the radiator instead of recirculating back through the engine. Their kit for the dual thermo setup includes an orifice to restrict the recirculating and force more through the radiator.

The dual fans is the next step but I don't think I'll need it. When that big fan locks up, it sounds like a helicopter out there. LOL!

 

[dirtydeed]

had a similar set up a few years ago. GMC 3500HD with the 6.5 turbo (or turd for short). They aren't exactly power houses but they will get the job done if you take care of them. Only thing I did was add a larger exhaust, front brakes, some tires and a new turbo boost solenoid (and triple gauges to keep an eye on temps/boost). Achilles heal to these things is the pump, more specifically the pump mounted drivers. They must be kept cool and lubricated too.

Mine had approx 50K on it when I acquired it. Put another 10K on it and sold it for more than I paid. It was a huge, gruesome orange crew cab beast with dump bed and fold down sides. But hey, the color matched my tractor for my landscaping business.

I sure do miss that beast now...should've kept her.


Good luck with yours.

 

[D2Cat]

How did you lubricate the pump mounted driver? New one on me!!

 

[L3700SU]

had a similar set up a few years ago. GMC 3500HD with the 6.5 turbo (or turd for short). They aren't exactly power houses but they will get the job done if you take care of them. Only thing I did was add a larger exhaust, front brakes, some tires and a new turbo boost solenoid (and triple gauges to keep an eye on temps/boost). Achilles heal to these things is the pump, more specifically the pump mounted drivers. They must be kept cool and lubricated too.

Mine had approx 50K on it when I acquired it. Put another 10K on it and sold it for more than I paid. It was a huge, gruesome orange crew cab beast with dump bed and fold down sides. But hey, the color matched my tractor for my landscaping business.

I sure do miss that beast now...should've kept her.


Good luck with yours.

First thing I did when I got her was put the injection pump control module in a cooler place and replace a bunch of solenoids. I also had someone that knew what they were doing time the injection pump. Like you said, not a power house but it does it's job. Didn't pay $50k for it either. Keeping the temp down has been my only issue and now I think it has been taken care of. I'm pleased with her and for a truck that old, it is not all rusted out. Frame is solid.

 

[hope to float]

Biggest engines we have here are 3.5l. Most common are 2.0 and 2.5 for towing. I am the proud owner of a 1.3 diesel lol. 60mpg. We are always amazed by the size of the machines you guys use over there. Love seeing those huge trucks hauling loads half the size we haul here.
Obviously speeds, distance, and temperature are huge factors for you guys but sometimes I think you underestimate what your trucks can do.
Here, if the van can't pull it, swop them around and put the van on the trailer and pull it with the tractor

 

[L3700SU]

Biggest engines we have here are 3.5l. Most common are 2.0 and 2.5 for towing. I am the proud owner of a 1.3 diesel lol. 60mpg. We are always amazed by the size of the machines you guys use over there. Love seeing those huge trucks hauling loads half the size we haul here.
Obviously speeds, distance, and temperature are huge factors for you guys but sometimes I think you underestimate what your trucks can do.
Here, if the van can't pull it, swop them around and put the van on the trailer and pull it with the tractor

You're right. I should put the dump truck on the trailer and pull it with the Kubota. LOL!

 

[dirtydeed]

First thing I did when I got her was put the injection pump control module in a cooler place and replace a bunch of solenoids. I'm pleased with her and for a truck that old, it is not all rusted out. Frame is solid.

Yes, remote (heat sink) pump mounted drivers were a great seller for suppliers. Oh, one other thing that went on mine was the vacuum pump. I believe a lot of guys nixed that as well and added a "turbo master". It was a spring actuated turbo boost controller, which eliminated the need for the vacuum pump and the boost solenoids. These things only used less than 10 lbs of boost.

Funny thing was when I bought it from a used car dealer, they sold it pretty cheap (10K at 50K miles) because it was a total dog, blew black smoke and couldn't get out of it's own way. It was a the boost solenoid ($25 part).

How did you lubricate the pump mounted driver? New one on me!!

I meant the injection pump needed lubrication...added a quart a straight 30 wt oil to each tank on every fill up and made sure to use power service. Sorry if I misled.

man, tried uploading pics, but can't. oh well.

 

[kirk1870]

I've been running 6.5s for 17 years, Heaths towing tune with Diamond eye 4" exhaust , your cooling mods and yes the water injection, would pull like a much newer truck.

 

[D2Cat]

My '95 doesn't see many miles, but it's working when it goes. Has a elec over hydraulic bale stinger on the back, Hiniker plow on the front, and an old Miller AEAD 200le welder in the bed with a solar powered battery charged on the dash! Never misses a beat.

 

[North Idaho Wolfman]

I am the proud owner of a 1.3 diesel lol. 60mpg.

My daily runner is a 2009 GMC 6.6l Duramax, 6 speed Allison, it's pushing about 500HP.
It's a heck of a change from the 350 chevy gasser and the turbo 400.

In the last five days, I've used the 20 foot flat bed trailer, hauled a damaged truck to and from town, moved the tractor and loader (L3450), cement mixer, bucket, forks, 3 runs of lumber, 208 2x4x20 at 7000lbs, 128 2x6x20 at 6400lbs, 296 2x4x10 at 5000lbs, then tomorrow I will be doing another run moving 70 sheets of 7/16 osb at 3200lbs and concrete at another 3000lbs.
Having fun rebuilding entire house of trusses and a roofing.

 

[shootem604]

I upgraded from a 94 Chevy 2500 gasser to a 2001 GMC Sierra 1 ton dually diesel. It's not fast, but it will pull anything. I've had 6 yards of wet dirt in the dump trailer behind, going up a long, decent grade on the highway, and I don't even think it shifted down.