towing heavy - coolant temps get high

[JAlford]

Recently I purchased a newer, heavier trailer to replace our older one. I have only towed it once for a very short distance, but the truck coolant temps climbed higher than normal. Very few original stock parts on the truck, almost everything has been upgraded with aftermarket parts, only the 5.9 block is still original in the drivetrain.
Our previous trailer was 13K#'s, the new trailer is #15.5K#'s.
Those of you towing the heavy newer 5th wheel RV's with the older trucks - did you find that the cooling system had to be modified? Is there an aftermarket radiator that increases the cooling capacity?
Thanks,
Jeff

NOTE: No need to tell me I am overloading the truck, I don't have a stock part in the entire truck. Dodge dealers absolutely scratch there head when they open the hood and just tell me that they can't help with anything on the truck, it isn't a Dodge any more. So GCVWR/GVWR doesn't apply to this truck.

 

[JR]

Sorry, GCWR still very much applies to suspension and more importantly, wheel and tire ratings.

Aside from that, what settings do you run the Edge and Smarty on? How's EGT's with those big injectors? If the GVW of your 5th wheel is 15,500 you should still be in the ball park of a dually and should not be above the capacity of the cooling system on a properly tuned truck.
When was the last time you had your radiator removed from the truck? They tend to get plugged up with oil especially if the crank case breather is still hanging off the front of the gear case and is impossible to clean without removing the radiator. Also need to check for proper fan operation if you haven't done so yet. The cooling system is pretty stout so I would check everything over thoroughly before condemning anything.

 

[JAlford]

Sorry, GCWR still very much applies to suspension and more importantly, wheel and tire ratings.

JR - point taken, but as I said, truck isn't stock at all. Suspension is a conglomeration of 2012 Dodge, Freightliner FL-60, and aftermarket custom. Wheels and tires are non-stock as well, but the trailer hitch wt doesn't even exceed the original 11K GVWR, only gets me to 10800 per the scales.

But back to the subject - I was running the Smarty on level 1 and the Edge on level 1. EGT's can get pretty high if pulling hard, around 1200-1300, but don't typically stay there long.
New aftermarket replacement radiator - basically very similar to the one Dodge sells as a replacement now that the originals are not available. I changed the thermostat at the same time, as well as the cap. That was just 2 months ago. I had the fan checked when the radiator was replaced, but I assume it could be failing now, it will be the next thing to change. Unless I have the trailer behind me, the temps never fluctuate, but EGT's don't get high either.

I have been considering changing the injectors to the 275 Bosch, but I am not sure that is really the answer. I have purchased a water-methanol injection unit to see if that helps, but haven't had time to install it yet. One item that is still stock is the intercooler, and therefore my boost is not real high, only hits around 30-32psi max.

 

[NC Hauler]

Don't know where you tow (mountains, level, both?), but the one limiting factor that I see, (not knowing much about your truck), is the 3:55 gearing...You're towing a heavy 5er and most would tow with 3:73 or 4:10...I know the newer Ram's (2013 up) will have 3:42 gearing, but they also have brand new frame and better front and rear suspension. Also higher GVWR's and GCWR's.

As stated, GCWR is affected more by gearing, (ie total weight of truck and trailer....Wondering if you didn't go to a 3:73 or 4:10 gearing that the issue with your heating problem might go away. Don't know that much about the tuner, but Level 1, I would imagine is the lowest setting, so wouldn't think that would be a problem...

 

[RustyJC]

We pulled a 16K GVWR 36' DRV Mobile Suites 36RE3 5th wheel with our 2002 3500 ETH/DEE (HO/6-speed) with 4.10 gears. The truck's rated GCWR was 21,500 lbs. It never overheated even pulling into the Davis Mountains in West Texas in 110 degF ambient temperatures. It was running DD2s and an Edge EZ and made 347/762 at the rear wheels. The temps would climb on steeper grades until the fan clutch kicked in which would pull it right back down to normal.

Having said that, heat rejection capacity is certainly one element the engineers use in establishing a truck's GCWR, and if your radiator is still stock size, then that heat rejection limitation is still there. Any degradation in heat rejection capacity due to a dirty/fouled radiator, faulty fan clutch, etc. will show up as overheating, especially with an engine that's making more horsepower (and, thus, more heat) than stock IF you're using that horsepower on the long grades to pull the heavier 5th wheel.

Rusty

 

[SnoKing]

When was your rad last serviced? And yes maybe you need lower gears for that much load as Jim pointed out. However that is more of an auto transmission issue that manuals, as they have a taller top gear. Maybe you need to slow down and climb hills at a "sweet spot" rather than using all the power you have to race up mountains?

Or the cooling system(if working at 100%) is just not up to that much combined weight when climbing hills. Sounds like you are at around 23,500 to 24K, maybe more based of truck load. Have you weighed the rig? There are wetting additives that increase cooling capabilities. If you still have original OEM radiator it might not be up to par even if recently serviced. And what about fan clutch is it the original OEM one? Based on you load you should most likely hear it locked up all the way up a mountain.

SNOKING

 

[mfurrh55]

I used to have an 01 with 3:55 gears and a 5 speed transmission, i was running a Banks kit on mine and rest of the truck was stock, i used to haul 19,000 lbs. of hay and trailer combination out of Utah to Tx.. truck weighed 8,000 lbs., haul over 5 mountain passes and had overheated only once going over Monarch pass in Colorado, pulled over and let it cool down and went on my way, 3:55 gears are ok for what your pulling,Monte

 

[JAlford]

NC Hauler - I hadn't looked into the gearing as a cause, for several reasons but primarily RPM being the same on the engine as other setups and me not putting high horsepower to the drivetrain. The truck pulls really strong with the trailer in tow, and I never have to push the "go pedal" hard when doing anything but passing. Additionally, my buddy has a old 7.3 ford 550 with the Dana 80 3.55 rear who hauls logs every week to the mill with no issues, weighing tons more. His truck is a 2wd, and he changed the ratio to 3.55 from the 4.56 to increase his fuel mileage. He has similar sized diameter tires as well.

I may have to look at the gearing, but really I'm not sure if it would resolve or create more issues? The higher my RPM goes above 2K, the hotter the engine gets. If it was the gearing, I assumed that dropping to 4th would lower the temps, but it actually makes the temps climb higher. My temps drop when I get the RPM's down on the engine. I had the exact same thing happen with my completely stock '06 3500 Dodge with the 5.9L(sold it). If you were towing and went to "OD off" position on the auto trans, it would overheat the engine rapidly even with towing the lighter wt trailer. That truck had 4.1 ratio rear and a lot higher GCWR than the stock '99.

I have never seen in any manufacturer specification where the axle ratio from a 3.5 range to a 4.1 increased the GCWR. There are a lot of other items to be considered of course, but even on the new trucks I haven't seen any specs that change the GCWR due to axle ratio change. I assume it does load the drivetrain components more with a lower ratio, but does it change the cooling requirements for the engine?

 

[RustyJC]

I have never seen in any manufacturer specification where the axle ratio from a 3.5 range to a 4.1 increased the GCWR.

I'll give you one. The 2002 3500 ETH/DEE I referenced earlier. 3.55 gears = 20,000 lb GCWR. 4.10 gears = 21,500 lb GCWR.

Here's another. My current truck (see signature). From the Dodge bodybuilder specs for 2011 3500 4x2 DRWs - 3.42 gears = 17,000 lb GCWR. 3.73 gears = 21,000 lb GCWR. 4.10 gears = 26,000 lb GCWR.

GCWRs go up as axle ratios get lower (higher numerically). Check the 2015 Ram bodybuilder website for 3500 DRW trucks where you still get a choice of axle ratios. Compare the GCWRs versus axle ratio selection with everything else remaining unchanged.

Rusty

 

[JAlford]

When was your rad last serviced?

New radiator, hoses, thermostat, and cap installed in Sept. 2014.

The fan clutch is really looking like it might be the issue, now that I am having to describe the issue in detail it would make sense that engine RPM increase and higher temps would definitely go hand in hand with a clutch failure. And it is one part that is still the original part, never been changed. The repair shop supposedly checked it and said it was fine, but I am not sure how you could be sure it would work as it is suppose to without some elaborate testing method. I think I will start there and see what happens. The trailer is in the shop until December for slide out room repairs, so I have some time to get the parts on the truck before I have to tow again.

 

[NC Hauler]

NC Hauler - I hadn't looked into the gearing as a cause, for several reasons but primarily RPM being the same on the engine as other setups and me not putting high horsepower to the drivetrain. The truck pulls really strong with the trailer in tow, and I never have to push the "go pedal" hard when doing anything but passing. Additionally, my buddy has a old 7.3 ford 550 with the Dana 80 3.55 rear who hauls logs every week to the mill with no issues, weighing tons more. His truck is a 2wd, and he changed the ratio to 3.55 from the 4.56 to increase his fuel mileage. He has similar sized diameter tires as well.

I may have to look at the gearing, but really I'm not sure if it would resolve or create more issues? The higher my RPM goes above 2K, the hotter the engine gets. If it was the gearing, I assumed that dropping to 4th would lower the temps, but it actually makes the temps climb higher. My temps drop when I get the RPM's down on the engine. I had the exact same thing happen with my completely stock '06 3500 Dodge with the 5.9L(sold it). If you were towing and went to "OD off" position on the auto trans, it would overheat the engine rapidly even with towing the lighter wt trailer. That truck had 4.1 ratio rear and a lot higher GCWR than the stock '99.

I have never seen in any manufacturer specification where the axle ratio from a 3.5 range to a 4.1 increased the GCWR. There are a lot of other items to be considered of course, but even on the new trucks I haven't seen any specs that change the GCWR due to axle ratio change. I assume it does load the drivetrain components more with a lower ratio, but does it change the cooling requirements for the engine?

I didn't notice that your transmission was a manual...but yes, GCWR IS affected by gear ratio...If you look at, for example, my truck, with 3:42 the GCWR is 29,000#, with 3:73 it's 32,000# and with 4:10 it's 37,500#...all identical trucks, only difference is the gearing. In a 2013 truck, same configuration as mine. Truck with G56 transmission and 3:42 has a GCWR of 24,000#, same set up with 3:73 raises GCWR up 2,000# to 26,000#.

I do understand shifting with a manual transmission would be more in your hands than an automatic governed by a computer....Agree there are a lot of other factors, sorry I couldn't help, but do know that gearing does affect GCWR of a vehicle.

99% of my towing is in the mountains, truck is stock, 5er at 16,200#, never had an issue with truck getting hot and know that shifting can be different with an automatic towing that kind of weight in the mountains between a 3:42, 3:73 or a 4:10.....

 

[JAlford]

I'll give you one. The 2002 3500 ETH/DEE I referenced earlier. 3.55 gears = 20,000 lb GCWR. 4.10 gears = 21,500 lb GCWR.

Here's another. My current truck (see signature). From the Dodge bodybuilder specs for 2011 3500 4x2 DRWs - 3.42 gears = 17,000 lb GCWR. 3.73 gears = 21,000 lb GCWR. 4.10 gears = 26,000 lb GCWR.

GCWRs go up as axle ratios get lower (higher numerically).

Rusty

Rusty - Wow, those examples are big jumps due to axle ratio changes . I guess I have never looked at the right year specs. My '99 specs are the same regardless of axle ratio, and the same with my '06 specs. When I called and talked with my local dealer last year about the 2014, they told me to get the 3.42 ratio as it was the same GCWR as the 4.1 (I was pricing the '14 trucks when we sold the '06).

I may end up looking at axle ratio changes, but it would be a last resort for sure. Since the suspension is custom made, and the ratio change requires an entire new axle setup, it would really be a lot of fabricating cost and new custom driveshafts. Big $$$ that I don't have right now.

 

[RustyJC]

I guarantee you - if you have a bad fan clutch and tow heavy under the right (wrong) conditions, it WILL overheat. You should be able to distinctly hear the fan clutch engage and disengage - I certainly could on my 2002 and can on my 2011.

Rusty

 

[RustyJC]

When I called and talked with my local dealer last year about the 2014, they told me to get the 3.42 ratio as it was the same GCWR as the 4.10...

With all respect to your dealer, he obviously wasn't looking at the Ram bodybuilder specs. GVWR wouldn't change with axle ratio; GCWR would. Perhaps he was confused between the two ratings.

Rusty

 

[NC Hauler]

Rusty - Wow, those examples are big jumps due to axle ratio changes . I guess I have never looked at the right year specs. My '99 specs are the same regardless of axle ratio, and the same with my '06 specs. When I called and talked with my local dealer last year about the 2014, they told me to get the 3.42 ratio as it was the same GCWR as the 4.1 (I was pricing the '14 trucks when we sold the '06).

I may end up looking at axle ratio changes, but it would be a last resort for sure. Since the suspension is custom made, and the ratio change requires an entire new axle setup, it would really be a lot of fabricating cost and new custom driveshafts. Big $$$ that I don't have right now.

As stated by someone else, your dealer was clueless, or he was thinking GVWR, Which ISN'T affected by gearing (stays the same on like trucks)...As I also showed you from a 2013 brochure...GCWR's jump drastically from 3:42 to 3:73 to 4:10... The 14 trucks have the same spread as do the 13's.

 

[JAlford]

I guarantee you - if you have a bad fan clutch and tow heavy under the right (wrong) conditions, it WILL overheat. You should be able to distinctly hear the fan clutch engage and disengage - I certainly could on my 2002 and can on my 2011.

The clutch is very likely to be the issue then, as I have not heard it engage or disengage at all. Would definitely be a quicker and less costly fix than new axles. Thanks to all for the responses, that is what makes the TDR such a great investment.

 

[JR]

Your 99s GCWR will also change based on gear ratios. It will be in your owners manual. If you don't have one, I can take a picture of the page out of my 98.5 This weekend as they are the same ratings.

 

[JAlford]

Your 99s GCWR will also change based on gear ratios.

I have attached the page below from the owners manual. The only change in GCWR for the 4x4 QC/CC is auto vs manual trans in the 2500. I assumed this was due to the H.O. engine only being available on a manual trans truck in '99. The GCWR for all 3500 trucks was 18000#, regardless of axle ratio or transmission type.

My '06 owners manual specs said the same thing - auto vs manual trans GCWR's were different, only it was reversed when compared to my '99, auto trans was a higher GCWR. Since I sold the truck, I don't have the manual to send the image of the page. I have mistakenly assumed that all the other year trucks did the same, which was an erroneous assumption.

The CAT scale weighed truck and trailer total, with loaded gear but not the toy, plus a half tank of water + 2/3 tank of gasoline (it is a toy hauler 5th wheel trailer) was GCW 23340#'s. With the older trailer, that we made several trips to Montana, Arizona, Florida, etc. was GCW 20980#'s typically.

 

[GAmes]

The clutch is very likely to be the issue then, as I have not heard it engage or disengage at all. Would definitely be a quicker and less costly fix than new axles. Thanks to all for the responses, that is what makes the TDR such a great investment.

Don't cheap out with a chain parts store fan clutch. I did and wasted a lot of time looking for overheating causes. Do it right the first time and pay the extra $$$ for an OEM. I get my parts from www.mopar4less.com Be sure to specify internet price.

 

[SnoKing]

Ok, get the cigar for being a he first to talk about the fan clutch. Not hearing it, 100% it is the issue. Snoking