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Towing questions
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=46066		 Page 1 of 2
Author:  irunmiles [ Sun Aug 23, 2009 10:53 am ]
Post subject:  Towing questions
I plan to tow a uhaul 6'x12' cargo trailer from Baltimore to Columbus, OH. I expect the trailer and load combined to be ~3,500 lbs. The trailer has automatic hydraulic surge brakes. There are a couple of short, but steep grades to pull. I've never towed long distance with the CRD.

-Should I tow in 2wd or full-time 4wd?
-I read where others use the O/D button and cruise control to lock in gears and rpm. I've never touched that O/D button. How and when should I use it?
-I need to change my coolant before this trip, how do you drain the system and reservoir?
Author:  chrispitude [ Sun Aug 23, 2009 12:15 pm ]
Post subject: 
We towed that same 6x12 U-Haul enclosed trailer, packed to the ceiling with stuff, from Colorado to Pennsylvania. You'll be fine towing in 2WD - my local transmission shop advised against towing in 4WD, indicating that the front drivetrain components in the Liberty aren't designed for the sustained load over hundreds/thousands of miles that towing will impose. Shifting O/D off up grades will keep you in lockup and will keep the engine and transmission cool and happy.

BE SURE you have enough tongue weight on the CRD! We loaded some heavy stuff in the back and the tongue weight was too light. We had very scary sway as soon as we got onto the highway. Unpacking a full U-Haul in a corporate center parking lot right off I-70 was not fun:

http://www.chrispitude.net/view.php?alb ... =11&size=2

If you can lift the tongue up off the ground by yourself, it's too light. Moving weight toward the front made everything pull just fine.

- Chris
Author:  BlackLibertyCRD [ Sun Aug 23, 2009 12:38 pm ]
Post subject:  Re: Towing questions
irunmiles wrote:
I plan to tow a uhaul 6'x12' cargo trailer from Baltimore to Columbus, OH. I expect the trailer and load combined to be ~3,500 lbs. The trailer has automatic hydraulic surge brakes. There are a couple of short, but steep grades to pull. I've never towed long distance with the CRD.

-Should I tow in 2wd or full-time 4wd?
-I read where others use the O/D button and cruise control to lock in gears and rpm. I've never touched that O/D button. How and when should I use it?
-I need to change my coolant before this trip, how do you drain the system and reservoir?


I towed a 6x12 loaded same route many times and just this year is using a new method of towing. That means keeping it in 4th gear even on flat land. Engine will run cooler and MPG will be greater. Here is the link:

http://www.lostjeeps.com/forum/phpBB3/vie ... hp?t=44497

BTW: set your GPS to avoid tolls and you will escape a big toll hit in PA, 2 extra axles. 8)
Author:  irunmiles [ Sun Aug 23, 2009 1:33 pm ]
Post subject: 
So if I set the cruise control to just under 2000 rpm, which is ~58 mph for my rig, do I just push the O/D button in at the bottom of a long uphill grade? Also, how do I drain the coolant from the engine and reservoir? There's no real obvious bottom hose on the radiator, at least I haven't located it yet.
Author:  Joe Romas [ Sun Aug 23, 2009 1:46 pm ]
Post subject: 
To the original question.

Re tongue weight. You want at least 10% of the total trailer weight on the tongue. 15% is ideal. However Jeep says to have a WDH (Weight Distributing Hitch) at and above 300# tongue weight.

Our travel trailer is around 3500# and we just returned to Columbus from Cape Hatterous NC. On anything but totally flat land the cruise control will have the transmission shifting all over the place and drive you nuts :shock: I've got the GDE tune and this trip was definetly better then the last as I was able to keep up with traffic in the mountains. As soon as you feel/see the RPM's dropping off hit the OD button. I was able to maintain 60-62 and staying under 3000 RPM's. Prior to the tune this was not always possible :cry: This trip's MPG figure was 19 and 20 and that is one or two above the last trip and a more pleasurable drive :D
Author:  BlackLibertyCRD [ Sun Aug 23, 2009 6:10 pm ]
Post subject: 
irunmiles wrote:
So if I set the cruise control to just under 2000 rpm, which is ~58 mph for my rig, do I just push the O/D button in at the bottom of a long uphill grade? Also, how do I drain the coolant from the engine and reservoir? There's no real obvious bottom hose on the radiator, at least I haven't located it yet.


Since you have a 05 your rpm and speed may be different depending on if you have the f-31 flash or not. If your cruising in 4th gear and it shifts to 5th at 2000 rpm then you want to set the cruise control just below the 2000 hash mark. The key is to find what rpm with cause it to shift into 5th with cruise on and coasting downhill and set cruise just below that. Believe it or not 4th will take up to 4% grade without downshifting. But there is quite a few 6% you will deal with. You should make it to the Ohio boarder on one tank of fuel towing this method.
Author:  tjkj2002 [ Sun Aug 23, 2009 10:45 pm ]
Post subject: 
Towing that much with a KJ(CRD or not) you should always lock out over drive and reduce your speed.Towing in overdrive will heat your trans up and kill your trans.You CRD guy's have enough problems keeping your trans alive better to keep it out of 4th and 5th all together.If your worried about MPG's while towing you may want to ship the stuff instead.
Author:  RTStabler51 [ Sun Aug 23, 2009 11:01 pm ]
Post subject: 
tjkj2002 wrote:
Towing that much with a KJ(CRD or not) you should always lock out over drive and reduce your speed.Towing in overdrive will heat your trans up and kill your trans.You CRD guy's have enough problems keeping your trans alive better to keep it out of 4th and 5th all together.If your worried about MPG's while towing you may want to ship the stuff instead.

On flat land I leave it in O/D. The only time I kick it out is accelerating and up hills. Temps are between 110-140 driving (varies because of outside air temps)
Author:  BlackLibertyCRD [ Mon Aug 24, 2009 6:26 am ]
Post subject: 
tjkj2002 wrote:
Towing that much with a KJ(CRD or not) you should always lock out over drive and reduce your speed.Towing in overdrive will heat your trans up and kill your trans.You CRD guy's have enough problems keeping your trans alive better to keep it out of 4th and 5th all together.If your worried about MPG's while towing you may want to ship the stuff instead.


I drove cross country twice in 4th tc lockup with no problem. I rather run at below 2,000 than 3,000 rpm for the engine/trans runs cooler and get better fuel mileage. That's towing 6x12 enclosed fully loaded.
Author:  ColoradoCRD [ Mon Aug 24, 2009 8:24 am ]
Post subject: 
The only time I touch the button when towing is when I hit long, 6 to 7% grades, like a mile or more when driving in the mountains. These are conditions when 4th or 5th gear don't give enough to maintain crusing speed. When the happens, I use the button and typically run about 45 mph at around 2000rpm in third gear.

Otherwise, on generally flat terrain, I am in 5th gear. I usually tow about 65mph, so the engine is about 1900rpm which is very near peak torque.

When towing I get 18 to 20 mpg.
Author:  danoid [ Mon Aug 24, 2009 9:47 am ]
Post subject: 
tjkj2002 wrote:
Towing that much with a KJ(CRD or not) you should always lock out over drive and reduce your speed.Towing in overdrive will heat your trans up and kill your trans.You CRD guy's have enough problems keeping your trans alive better to keep it out of 4th and 5th all together.If your worried about MPG's while towing you may want to ship the stuff instead.


I disagree. My 02 gasser needed to stay in third (because it didn't have the torque), but if I keep the CRD in third it gets hotter than in fourth. The hydraulic fan will not engage at that high an engine rpm. Also the 3.7L turned 9 mpg vs the CRD 12-15. Percentage wise that a major difference.

Keep her in 4th - keep it locked up - it will out tug your expectations (and any gas KJ made).
Author:  warp2diesel [ Mon Aug 24, 2009 6:48 pm ]
Post subject:  Cruse on flat lands is OK but not on hills.
irunmiles wrote:
So if I set the cruise control to just under 2000 rpm, which is ~58 mph for my rig, do I just push the O/D button in at the bottom of a long uphill grade? Also, how do I drain the coolant from the engine and reservoir? There's no real obvious bottom hose on the radiator, at least I haven't located it yet.


I have EGT, BOST, and Trans Temp gauges on my 06 CRD. Once I was climbing a Bluff and used cruse control, the EGT shot up over 1400f when the engine revved up to 4K. On the next Bluff, I disengaged the cruse and used my foot and climbed a steeper bluff and kept the EGT at 1200f. Since then I opened up my exhaust to 2 1/2" including the restrictions at the Cat to Muffler flange. I have not towed since then, but my EGT has dropped 150f - 200f for the same conditions. Also my Cat cleaned its' self out and the back pressure gauge I piped in between the Cat and Turbo has stayed on 0.0 PSI. At first I could not believe the back pressure problem went away, so I checked the line going to the Back Pressure Gauge and there are no leaks.

Conclusions: 1) Use your brain and foot when you climb hills to keep the EGT down. 2) Consider going to 2 1/2" Cat back including the flange restriction that is 2 1/8" inside the Cat flange.
Since all my Bluff hills are short runs and the Trailers I have towed have small frontal area, I use 5th lock up when I can. I towed a 6' X 12' U-Haul and did not have any frontal area issues or long grades requiring me to stay in 4th. Just remember the frontal area of the U-Haul is much less than travel trailers. If I were towing a Travel trailer, I would consider using 4th lock up.
FYI: My trailer is a 1900# Tandem Axle with 5K axles, 12' Brakes, 16' bed with a beaver tail. I plan to haul 7000# from West Central Illinois to Southwestern Michigan. The only reason I will be able to do this is due the the lack of frontal area (only 26 Sq Ft plus load frontal area minus frontal area of the CRD) . When I did tow 3500# it towed great with no problems.
Author:  BlackLibertyCRD [ Mon Aug 24, 2009 10:02 pm ]
Post subject:  Re: Cruse on flat lands is OK but not on hills.
warp2diesel wrote:
the EGT shot up over 1400f when the engine revved up to 4K.


Wow, if you climbed a 10 mile 6%+ grade at that RPM and speed, your engine and trans could overheat. Like I said before 4th gear for up to 4% grade and hit the overdrive button for steeper grades. That will be about 2600 rpm at about 60 mph and the engine will be a lot happier.
Author:  warp2diesel [ Mon Aug 24, 2009 10:11 pm ]
Post subject:  Re: Cruse on flat lands is OK but not on hills.
BlackLibertyCRD wrote:
warp2diesel wrote:
the EGT shot up over 1400f when the engine revved up to 4K.


Wow, if you climbed a 10 mile 6%+ grade at that RPM and speed, your engine and trans could overheat. Like I said before 4th gear for up to 4% grade and hit the overdrive button for steeper grades. That will be about 2600 rpm at about 60 mph and the engine will be a lot happier.


That was with the cruse engaged and it down shifted its' self.

I am not the first to claim the CRD TCM reaks of Gasser programming.

Never had that happen with the cruse disengaged.

Your Travel trailer has a lot of frontal area, right?
Author:  BlackLibertyCRD [ Mon Aug 24, 2009 10:33 pm ]
Post subject: 
When you hit the od button, the trans will go to 3rd tc locked. If you go up steep grades with cruise on and don't hit od button going up steep grade the transmission will downshift to 3rd tc unlocked. This create more heat in the transmission that is transferred to the cooling system and to the engine. More RPM's mean more fuel and more heat going out the exhaust causing you EGT to go high. It not just a programing problem but something that could be done better with a stick shift.
Author:  tjkj2002 [ Mon Aug 24, 2009 11:57 pm ]
Post subject: 
danoid wrote:
tjkj2002 wrote:
Towing that much with a KJ(CRD or not) you should always lock out over drive and reduce your speed.Towing in overdrive will heat your trans up and kill your trans.You CRD guy's have enough problems keeping your trans alive better to keep it out of 4th and 5th all together.If your worried about MPG's while towing you may want to ship the stuff instead.


I disagree. My 02 gasser needed to stay in third (because it didn't have the torque), but if I keep the CRD in third it gets hotter than in fourth. The hydraulic fan will not engage at that high an engine rpm. Also the 3.7L turned 9 mpg vs the CRD 12-15. Percentage wise that a major difference.

Keep her in 4th - keep it locked up - it will out tug your expectations (and any gas KJ made).
Kinda odd,when I pulled 4500lbs enclosed 6'x10' trailer(was tall,80" from deck to ceiling) from Ft Lewis WA to Ft Carson CO my lifted,5500lbs,265/75'ed KJ pulled about 16mpg's at 65mph in 3rd gear(3200rpms) and there was quite a few steep,long upgrades.

The 45RFE/545RFE just doesn't have stout enough overdrive's to withstand towing,even if in lockup.This is a situation where torque is your enemy.
Author:  BlackLibertyCRD [ Tue Aug 25, 2009 6:27 am ]
Post subject: 
Towing at 65 mph at 3200 rpm will be with the od button pressed. That would put it into 3rd with tc locked which is good for the weight you were pulling. If the tc wasn't locked such as allowing it to shift out of od by itself the tc would be causing the trans fluid to heat up and the rpm to be much higher. That is demonstrated by warp2diesel response.
Author:  nursecosmo [ Tue Aug 25, 2009 6:36 am ]
Post subject: 
tjkj2002 wrote:

The 45RFE/545RFE just doesn't have stout enough overdrive's to withstand towing,even if in lockup.This is a situation where torque is your enemy.


The overdrive is more than adequate for towing in the 545RFE. I don't know of anyone who has broken one yet. Torque is allways better for towing. Don't hate the CRD man.
Author:  yakers [ Tue Aug 25, 2009 7:55 am ]
Post subject: 
I tow a travel trailer that may come to 3,000 lbs max, usually below that. When I am cruising flat land I tow @60MPH in 4th. Seems to work well. Any grade seems to require OD off (3rd). I could always tow in OD off/3rd but I get better milage and the engine is quieter in 4th.Obviously there is more fuel use in 3rd but is there any advantage wear wise to always staying in 3rd?
Author:  danoid [ Tue Aug 25, 2009 8:59 am ]
Post subject: 
tjkj2002 wrote:

The 45RFE/545RFE just doesn't have stout enough overdrive's to withstand towing,even if in lockup.This is a situation where torque is your enemy.


Again, I'll have to disagree. The 545RFE transmission is fine. It also worked fine in my 2004 Durango with a Hemi. Torque, which allows the engine to stay at lower rpms is always your friend towing a trailer. Don't blame the transmission if the engine can't pull the load. By definition, a transmission only transmits what it's given.

2002 KJ 3.7L - 45RFE - 3.77 axle, tows in 3rd gear @ 65 mph = 9 mpg
2004 HB 5.7L - 545RFE - 3.55 axle, tows in 4th gear @ 65 mph = 10 mpg
2004 KJ 3.7L - 42RLE - 3.77 axle, tows in 3rd gear @ 65 mph = 9 mpg
2005 KJ 2.7L - 545RFE - 3.77 axle, tows in 4th gear @ 65 mph = 14 mpg
2008 WK 3.9L - W5A580 - 3.77 axle, tows in 5th gear @ 65 mph = 14 mpg

All with the identical 27', 5600#, 64 sq ft travel trailer. There is nearly 17,000 miles of data here, with two results, around 9-10 mpg or 13-15 mpg. What is apparantly the main factor? Spark plugs - not the transmission.
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