Tori

Just upgraded our bumper pull, 24' trailer, and it's about 9K loaded. Previous trailer was 6500k loaded, so pulling wasn't really much of a stress on the truck. This new trailer however is MUCH more noticeable. Engine temps are up, and so is trans temp.

On a recent trip, 100* air temp, once we got off the hwy and onto slower 2 lane roads with hills, Engine temp was 210* at times, and trans temp as much as 215* Mostly towing with tow haul engaged, and kept the EGT's down.

I'm wondering if a move to 4:10's is recommended for this weight, or should i be upgrading the trans cooler ? Not real jazzed to regear a 4x4, but will do so if i need to.

I use the truck primarily for towing, but i'd like to maintain my MPG when not towing.

Thanks for any input/opinions you can share.

silverram323

I re-geared my 2001 from 3.54 to 4.10, made a big difference in pulling, it struggled a lot less, come out of the hole better, and i only lost .5 to 1 mpg. If i ever buy another diesel pick up, it will have 4.10s. I only use my truck to tow now, and when i bought my 1995 12v it came with 3.54, if it wasn't such a good deal i would not have bought it cause of the 3.54.

It cost me $2200 for the parts and labor, not the cheapest but it does make a noticeable difference. Oh BTW, my 01 had 535 hp, so it wasn't lacking any power by any means. It also dropped my egts towing 250 degrees with the gear change.

Tori

Thanks Silver, i can't imagine trying to do work with 3.54's I'm gonna price out a set of rear gears and maybe give them a try. See how they effect the haul, and the MPG. As it is, i'm currently getting about 10.5 hand calc. MPG when towing.

jrs_dodge_diesel

3.55's are great when unloaded.

That said, I wish I had something better for when I do tow. 3.73s at a minumum.

KATOOM

Granted we're not talking the same truck but just pointing out that I have 3.54's and I tow around a 14k 5th wheel and ALL my engine drivetrain temps are well within the safe zone.

I used to tow a 8000 lb TT and obviously the truck had no problems whatsoever. But when we moved up to a "huge" 5th wheel I knew I had to help the truck as much as possible. Better intake, larger exhaust, coolers on my 5 speed with blanketed exhaust, Mag-Hytec on the rear differential with synthetic, an EZ, and making sure the radiator fins and coolant is clean. I can tow down the freeway in 100* weather and 200*-205* engine is normal, tranny around 170*, and differential around 185*. Pulling hills the engine can climb to around 210*-215* and the tranny and differential can reach 200* but only for brief moments. Again, this is during the hot summer weather. In the winter I hardly watch the temp gauges.....

So point being, if you cant keep temps under control with a mere 9000lb TT then maybe you need to start looking into means of helping your truck stay cooler. Lower gears will certainly change the drivetrain leverage but I cant see why there would be any reason why you'd need 4.10's. If it helped.....it would be minimal at best because you're still working the engine and drivetrain and pulling a large billboard size brick down the road.

Maybe you should save the high dollar investment it would take to swap gearing and the loss of fuel mileage you'd see unloaded, and rather spend some of that money on an cool air intake and free flowing 4" exhaust system. Those would help reduce EGT's and EGT's are directly related to engine temps. Keep the EGT's down and the engine cooling system works more efficiently.

Tori

Thanks KATOOM for the suggestions. Being from California and having to pass semi annual smog inspection, i could only do a CAT back system. Do you think that would be enough ? I also do not want to listen to the drone of a louder exhaust, so that may be a deal breaker right there. I do have a drop in K&N, but maybe there could be some additional gains with the CAI.

Is there improvements to be had with a larger trans cooler ?

KATOOM

I honestly cant give you much advice in regards to exhaust systems for your 3rd gen truck because yes.....CA continues to rob more of your freedom and income everyday by supporting bogus diesel smog laws. Even though my truck comes with zero emissions components, I still have to pay $40 to smog my truck. But nonetheless, you should have better luck asking questions about exhaust gains and noise issues in the 3rd gen section of forums, as I dont want to lead you astray.

As for the K&N, I cant suggest more that you should quickly ditch that air filter as its letting in considerable dirt/debris into your intake. Probably noticeable too if you pull off the turbo intake tube and find dust on the inside of the tube and turbo blades. K&N isnt a bad company but in order to make ANY air filter flow better the only way to achieve that is to let more air in. This is why you see huge air filters folded up in a manner which offers flow but more media coverage to insure proper filtration. The K&N stock replacement cant offer more media coverage because of the limited space in the airbox so you simply get more flow and less filtration as the turbo sucks massive amounts of air through. A better designed aftermarket intake system would do you much better.

And a secondary tranny cooler will offer better tranny temps and a deep aftermarket tranny fluid pan will offer more fluid capacity. If towing temps are a concern, definitely both of those would be something to think about. All lubrication fluids/oils are generally OK up to around 225*. After that is when things are too hot and lubrication properties are becoming compromised. Oxidation sets in and if it gets hotter than 225* for more than minutes, changing the fluid is a good idea.

CrazyCooter

You are fine with what you have..... Your load is way under the truck's abilities.

I have been running 29-31k combined for the past 4 years with taller gearing than you, but with a manual trans. Coolant temps run 213°+ in cool weather with trans temps 235°+ all day on longer trips.

Your trans is cooled by an oil to water cooler, so it's not going to stay cold unless you cool the coolant. My buddy actually installed a 180° thermostat in his and I would assume that would result in the trans temp drop since the water would run cooler. Your fan still won't lock in until the computer's pre-determined temp though.

I'm betting your egts are OK too judging by your tuner and power level.....these trucks run over 1500° out of the box and the Smarty usually runs cooler even with a 90 hp tune. If you want to see a serious egt drop, you need a less restrictive turbo. Since you are in CA, I'd be looking at one of the guys that mod to exhaust side of your HE351 so it look stock from the outside for you visual. My buddy just got one done from Bell Turbo.

I knew I was pushing my truck on the longer faster out of state trips, so I semi retired it with a tractor to share duties.....

You have a lot left on the table before needing a gear swap!

Danderson

Numerous dyno tests with and without the stock intakes have shown minimal improvement under 400 hp levels as well as the cats which aren't a consideration in California.
A freer flowing muffler would help a dab and chucking the K&N and doing the www.psmdiesel.com mod or Home Depot one with a new 4" stock filter will improve flow and protect your engine.

KATOOM

Tony, I think we completely agree here that the OP is far from the limitations of the truck and gearing. But dont forget that the 2nd gen trucks dont have electric fan clutchs so the ECM will have nothing to do with regulating the fan cycle. These manual clutch fan thermostats fully engage at 205*.

And I would presume your friend may have noticed a loss of fuel mileage when moving down to a 180* thermostat because the 24 valve engines run notoriously cooler cylinder head temps which is why they need the hotter thermostats. They just dont run very efficient too cold. I've read and been part of lots of discussion and experiments in messing with thermostat temperature variations on another forum. No matter what anyone tried, the 190* seemed to be best. Your friend would have been better off running a secondary tranny cooler plumbed in post the heat exchanger instead of trying to lower the coolant temp 10*.

And also, I'm not trying to call out errors but running 1500* for any length of time in a 2nd gen will turn the 5.9 internals into goo. I'm actually surprised you have such luck running the CR engine that hot since they tend to melt pistons pretty easy. However all that said, the 6.7's do run much hotter EGT's than the 5.9's.

Again, we agree but just pointing out that there are differences in the 2nd gens.
Oh yeah, I still plan on stopping by one of these days when I'm in Redding to check out your trailer.

CrazyCooter

I thought we were talking about 3rd gens here? What is the OP towing with? Maybe I'm confused? Are there any of them old 2nd gens left on the road? Isn't everyone driving 5th gens with 700hp and 60K towing ratings?

You are correct in that the lower temp thermostat in the 3rd gen is a bonehead move. I'm sure this will cost him longevity too. Maybe that's why his trans has over 150K on it running a tuner, towing heavy trailers, and racing up the hills? He thinks it's because he has the trans serviced every 15k and bands adjusted....... HE is an old school Cummins tech and they do it the old way......

I don't run my truck at 1500°+, but that's what ran stock. I usually try to stay 1400-1450 max, but have run 1350-1400 for 2 hours into a headwind. I think its all in the tuning and supporting mods. If you are gonna roll as heavy as I do in the hills, not much choice....... 94K miles mostly towing with the only failure.....fan clutch. High RPM's eats them!

My opinion is restrictive exhaust manifolds and turbo is where the problem is on 3rd gen 5.9's.

If I knew what I know now, the only hard mods I would have would be a drilled stock airbox w/ drop in S&B filter, HighTech Stainless manifold, Small towing turbo, Pusher Intake/Cross air, and a good Smarty/EFI tune.

PacBrake is a must also......

KATOOM

I think you're right..... I think he does have a 3rd gen after looking at the picture. I'm looking on my phone too and the sigs don't show if they're even there. But you're so right in mentioning an exhaust brake. A MUST item for towing.

KATOOM

I haven't seen this setup in years..... I'm not sure if this one is from the same people or is a knock off, but the first system which utilized this very concept years ago was the Scotty, followed by the Scotty II. Yes, it definitely worked to reduce EGT's but because it pulled the cold air directly through a 4" hole you had to drill in the firewall HVAC cowl area, the increase in turbo noise inside the cab was immense. So much so that it became a joke as many passengers and wives/girlfriends hated the noise. So I can only imagine that this psmdiesel system would do the same.

j_martin

Girlfriend whining, PMS deisel......oh the irony of it all.

oops, a little dyslexia there..

What's wrong with a front scoop air intake for positive pressure cool air? Pulling it from what amounts to the cab heater intake duct is crazy.

Danderson

I cherish the lack of whistle in this truck and the psm setup didn't affect the noise at all. I couldn't even handle the BHAF in my 24v.