WOO HOO!! Long tow.. no problems.

[scubabri]

Towed my 35' fifth wheel from Hemet, CA to Houston, TX over 2 days. No problems (other than taking a rock on the windshield in the last 20 miles). Got about 9 mpg.

Phoenix and Tuscon were a bit challenging because it was hot out, about 100 deg. I found that I couldnt get above 45 mph without my temps getting above 210, not overheating just made me nervous. I think that replacing the stock fan with the duramax replacement may have helped this situation. Granted it probably wasnt wise to be towing in the heat, but I really had no choice.

Once I got out of Tuscon the temps dropped and I was able to get back up to 60mph on the flats.

I dont know why I constantly worry that the truck is going to blow up. The stress is just to much, so I think when I get some cash, I'm going to sell this truck and get something newer.

 

[WarWagon]

What else have you done for the cooling system?
HO water pump?
Clean radiators?
New fan clutch?

With a Kennedy low temp fan clutch and low temp thermostat you should be able to touch 210 before the fan is holding you there. And that is sneaking up on 210 with lower power. WOT will bring the fan on before 210. This is my experience out here with a DB2 IP and holding ~60 MPH WOT towing heavy. Lower speeds on higher grades though like 43 MPH on 10% grades.

A newer Duramax will hold the speed limit better, but, will also have temp issues out here. You will need an aftermarket oil cooler and other goodies to keep that cool out here as well!

 

[great white]

Well, being on a forum that specializes in your particular vehicle is kind of a a double edged sword.

On one cutting edge, you gain knowledge that enables you to build a more reliable and capable rig (IE: PMD relocation, oil, gauges, temps, driving styles, etc).

On the other edge, you get to see all the nasty little problems that crop up in the design (IE: pmd, block cracking, harmonic damper failures, broken cranks, etc).

Double edged sword.

Now, a newer vehcile carries with it some advantages:

less mileage
newer design
more power
easier to find parts
etc...

But, they're not perfect either.

Hammer on a new DMax long enough without knowing egt's and it will also fail. New dmax's are more powerful than the 6.5, but they are also susceptible to the same overheating problems. I've seen lots of posts on that very fact.

Dodge diesels have that great cummins in it. But it's wrrapped in a dodge. I've often heard the Dodge Cummins described as being just like a snickers bar: you pull of fthe wrapper, throw it away and keep the good stuff inside.

Ford. Well, I don't follow the ford diesels too much, but haven't really heard anything bad anbout them either. Mostly good comments from a work truck point of veiw but little else (well, guys seem to like the integrated brake controllers).

If buying a newer truck makes you feel safer, go ahead and do it. But keep in mind unless it's brand new, you can have a lot of the problems (and concerns) you have with the old 6.5 right now.

I'd say most guys running the 6.5's on the board here do it because they can't afford to shel out 40,000 for a new 'max.

Persoanlly, I run my 98 becuase I like the body style. As soon as I scrap together enough cash reserve, there's a Dmax drivetrain out there somewhere with my trucks VIN on it....

 

[Veg_Out]

I've just ordered the Kennedy fan clutch myself. I had the Hayden Severe Duty setup I'd heard so much good about, and it came on way too late. Idaho has flat roads and straight up walls to climb. So, I need the clutch to engage early and often once I hit the wall.

Especially once these rigs are turned up, get the best possible cooling goodies and clean those condensers out like your rig depends on it! Also, change your harmonic balancer with every oil change. Just kidding.

 

[scubabri]

Since I dont have an EGT (yet) my theory was, if my max boost was 14psi, I would push it to no more than 10 psi sustained and 12 psi for short runs, and that was never WOT. I dont think the temps would have kept climbing, but I didnt want to chance it. As far as the cooling system, it has whatever was stock in the 97, which I think includes a HO water pump. I have 2 tstats, both have been replaced. Before I left, I made sure that the radiator was clean. I really think the thing that is lacking is a clutch that comes on earlier. I notice also that at higher RPM's there is a longer delay for the fan kicking in, maybe the clutch on the fan is bad, or going bad?

I do have another question, the TCC lockup, it seems that when I'm in D, that there is a major rpm difference between D and 3. It seems like it really is missing a gear, and if I understand thats the TCC. Will the TCC mod find that "lost" gear for me? Out of my whole drive, this is my biggest complaint.

I dont plan on towing anytime soon, but thats just a plan, suprises happen and who knows I might find a job in Colorado, wanna be prepared.

Thanks for everyone's help, I do know that without this and the dieselplace forum, there is no way the truck would have survived towing it locally around Hemet, let alone towing to Redding and then back and then to Houston. Thank you all so much.

b

 

[ak diesel driver]

TCC mod won't work on obd2 throws codes. It should lock up in 3rd. On mine when it downshifts it unlocks the tcc for a few seconds and then you can feel it lock back up. There is a big diff in rpm

 

[scubabri]

Yes, it does it in 3rd, but I was almost sure that I felt it do it in D, maybe it just shifted to 3rd. When the RPM drops is that locked up or not locked up? Isnt there a danger of towing in whatever the RPM dropped mode is? I dont want to burn something up.

 

[ak diesel driver]

OD is 4th gear and when you see/feel the rpms drop the tcc is locking up. GM recommends towing in 3rd. Most only tow in 3rd if OD is too much.

 

[WarWagon]

4L80E is fine towing in OD, it is the strongest transmission GM makes. (Hell my first 4L80E almost made it around the block before 4th blew up on me. It only had 125K on it and I just got it...) The other lighter transmissions were not recommended to tow in OD and have a sticker on the driver's side door saying don't...

2 T-stats means HO water pump.

So you are at bad fan clutch or plugged condenser/oil cooler. Pull the grill and pull the oil cooler to look between it and the condenser. Bet there is a mat there if you have not cleaned it... When was the last time the radiator was pulled out and cleaned? This is a required choir for our body style every few years.

AN off the shelf Hayden heavy duty clutch will do ok, but to keep the temps down you need to mod the clutch or get a special factory cal low temp one. Fan clutches are only good for 5 years anyway as they wear out...

You can also check your air filter and intake/exhaust for restrictions that could also cause power loss and or heating issues.

 

[Diesel -T]

My setup is somewhat similar , except trailer (5th wheel) is 30ft ) In regards to down shifting or locking unlocking of tc , mine will unlock only sometimes ,(a 150 -200 or thereabouts rpm drop). Then drop to 3d if need be .Other times it appears to drop directly to 3d from 4th locked to 3d unlocked all in one fell swoop ,a big rpm drop . .