Mountain pulling

What is the proper procedure for pulling in the mountains with an auto tranny, both at hwy speeds and at slow speeds? The reason I'm asking is that both times I have pulled steep grades (lone pine, CA) and Getting up on the Blue Ridge (on the wrong road), I've had to pull over and let the tranny cool down. Both times I was going slow (below 40 mph) and I am just wondering if I'm doing something wrong. Thanks for your input.

I've only done one trip with my set up through the mountains (Homestake Pass in Butte, MT and Lookout Pass outside Missoula). Even though my 6.0 is a bit stretched to its limits with my WC tranny temp was just fine. I simply kept the tow/haul system on and kept the RPMs down. I would watch the RPMs more than the speed limit, kept it @ or around 3500. Once and a while the tranny would hunt for a different gear and RPMs would spike, I would just take the foot off the gas and let it settle down. Tranny temp stayed normal as long as I kept this rule of thumb.

Hope this helps!

Brad

I have the same truck and set-up you do and (knock on wood) have never had a problem with the transmission over heating. When towing I always use tow haul setting. We have pulled the Cat (29RLBS) to Alaska, Key West, Niagria Falls and all points between with no problems. The only thing I see a lot of other drivers do is let their RPM's get down when pulling long grades. This will cause the temp to rise. One thing you might check is to make sure the radiator and condensor are clean. I put a screen in front of my radiator when the truck was new so no bugs get in the fins and check it all the time. Hope this helps Jim

I think you are going to slow to keep the torque converter locked. Keep it in tow/haul mode and keep your speed/RPM's up; do not let it hunt.

Keeping the torque converter locked will help you; a slipping torque converter creates a lot of heat. I don't know how the Dodge transmissions are programmed, but the stock Ford program will keep it locked above (guessing here) about 45mph. Unless you are on the brake; then the TQ unlocks. My modified transmission will not unlock until the speed drops below 28mph. I also have a manual switch that will lock it to the point of stalling the engine.

That's easy to say, a little harder to do. You probably need to keep your speed a little higher to make sure the TQ stays locked; try to be aware of when it is locked or not. When it locks it will almost feel like the truck shifted into another gear. When it unlocks, you will hear it in the engine.

Another recomendation is an extra/bigger transmission cooler. They are not very expensive.

If your transmission starts to get hot and you are not near the top of the grade, you don't have much choice; pull over, let it cool off and save yourself thousands.

Good luck.

Thanks everybody. Scott, I think you nailed it on the head!! I have pulled several mountain passes at speed with no issue. Both times I've had trouble, were at less than 40-45 mph. At Lone Pine, I didn't know what I was getting into trying to get up to the campground (I would have put the truck in 4-lo and just crawled up) and the other was going from Linville,NC up to the Blue ridge on Hwy 221. I knew I was in trouble as I passed the sign that was blinking saying that I was too long to continue on. Problem was, it was too late to do anything about it and luckily, I didn't run anybody else off the road in the hairpin curves. Needless to say, I had to go slow and yes the truck was working hard.

I think I need to look into this whole manual lock thing!! Also, I am going to make sure that the radiator and cooler are clean, I usually give them a real good cleaning once a year, but more often won't hurt anything.

While not exactly equivalent, we have a similar problem with manual trannys. It's called lugging the engine down and it happens when the gear that you're traveling in is too high for the engine rpm's. You begin hearing the engine struggling and if it really gets bad it can start bucking and actually stall out. Each gear in the tranny has an rpm range that it likes. It really won't get above a certain rpm no matter how much fuel you feed it and it will buck and stall out below that range. With a manual it's knowing the rpm ranges of each gear and shifting up or down as needed to stay within that range.

In an auto tranny each gear is programmed to shift into the next higher or lower gear when the module senses the engine approaching max rpm's for that gear, or senses the engine beginning to struggle. That's why an auto tranny will begin to hunt between gears on a long hill and that creates heat.

I'm not too familiar with the new tow/haul modes on the newer trannys because I haven't driven an auto since 2004 when I traded my old 2000 Ram 1500 with the 360CID V8 and the now infamous Dodge 48RE auto tranny. It didn't have tow/haul.

I think it would be good to learn the sweet rpm ranges for each of the gears in your tranny and keep the rpm's in the sweet range by downshifting as necessary. That should keep your tranny temps down.

also make sure your raditaor area is clear of dead bugs, leaves ect. this is the location of the tranny cooler. I have to clean mine every year. Dont lug the engine, a CTD can run forever at high rpm, the higher rpm keeps your trans. line pressure up, keeps the turbo spolled in turn keeps you EGT lower. In the future you may want to upgrade your trany. I dumped 6K for a DTT tranny. best thing I ever did.

"High" or "higher" is relative. What rpm are you talking about?

kcnielsen wrote:"High" or "higher" is relative. What rpm are you talking about?

Ken,

The range is going to depend on alot of variables. You can see by my signature that I have:

2004.5 HO 5.9L Cummins
NV5600 6sp tranny
4.10 diffy
Michelin 17" tires

My personal minimum for downshifting is 1500 RPM in all gears
My personal maximum for upshifting is 2500 RPM from 1st to 2nd thru 5th to 6th

If the rpms get below 1500 I can really tell by the way the engine sounds and the truck reacts, ie. shudder, getting ready to stall out.

I see you have the newer G56 but I don't know what diffy you have (3.73 or 4.10?) They tell me that the gear ratio for 4th, 5th & 6th is alot different than mine.

When pulling uphill, I drive by engine sound,boost and EGT gauge. If your on a hard pull the boost should be near its max. this will keep your EGT's down. Keeping the engine in a higher rpm makes for more air flow through the radiator, intercooler, trans cooler,and engine. I would suggest to anyone who is towing to have at least boost and EGT gauges. If you lug the engine up hill while providing more fuel to the engine, you dont have enough airflow from the turbo to prevent a meltdown. The pistons in a CTD are aluminum and will melt just above 1300 deg. Most often cylinders #5 and 6

Please, I urge anyone pulling with a diesel to install at least boost and EGT gauges. you must keep air flow through the engine to lower EGTs. Down shifting or up shifting should be done due to engine conditions and not tow rig speed. I can't stress how important this is

Put the transmission in tow/haul, factory installed tow package, and set the cruise control.

I only have GM 6.0 gasser, so I just struggle:(

Herrmann is correct. I drive by by the EGT gauge. You'll find that lugging the engine is the worst thing you can due; results in highest EGT's. When my EGT starts getting too high (I don't let it get above 1200), I either downshift or back off the loud pedal.

The stock computer should not let your truck get too hot; you really need the EGT gauge after installing a chip.

With my '05 PSD I just set the cruise (65) and Tow/Haul and let the truck handle everything, never had a problem.

Just want to say if you need to pull over to cool a automatic transmission down. leave the engine running and put the transmission in neutrel not park. most auto trans do not circulate the fluid while in park.

Lou,

I have a 5.4L V-8 gas engine. First time it was up to Alaska the
spring after the TV was delivered and RV bought, then 2 roundtrips from
there to Florida via either San Diego CA to the south or Bangor ME to
the north.

Nuthin wrong with a gas engine.

schrowang wrote:

kcnielsen wrote:"High" or "higher" is relative. What rpm are you talking about?

Ken,

The range is going to depend on alot of variables. You can see by my signature that I have:

2004.5 HO 5.9L Cummins
NV5600 6sp tranny
4.10 diffy
Michelin 17" tires

My personal minimum for downshifting is 1500 RPM in all gears
My personal maximum for upshifting is 2500 RPM from 1st to 2nd thru 5th to 6th

If the rpms get below 1500 I can really tell by the way the engine sounds and the truck reacts, ie. shudder, getting ready to stall out.

I see you have the newer G56 but I don't know what diffy you have (3.73 or 4.10?) They tell me that the gear ratio for 4th, 5th & 6th is alot different than mine.

Thanks, Schrowang. You answered my question. When you talked about high RPM's, I was thinking the 3000RPM range.

I have the 3.73 diffy. My truck is pretty well stock as far as the engine and tires goe. In 6th gear I'm turning about 2000 RPM at 62 MPH and I find I get the best fuel economy at about 2000RPM.

I like to upshift at 2500 RPM max as well. I find the EGT's get too high if running at max load below about 1800 for very long. For very hard pulling it does best between 1900 and 2400.

I dont know if the 2005 has the O/D lockout, but if it does that will allow the trans to lock up in 3rd gear. IIRC my dads is an 05 and it does allow OD lockout on the Towhaul toggle switch.

Those setting the cruise and tow/haul mode and forget probably haven't towed many low speed/steep inclines/high altitudes passes in the mountains. There are a few issues that cause this problem. The Turbochargers are not in the efficiency zone at altitude, so that usually means knocking it down a gear for safe EGTs. Many times that means without assistance from the driver to make decisions on gears selection etc, the transmission will have to run with the TC unlocked causing massive heat issues.

1st gear never will lock (good thing due to torque output), 2nd gear is
good for steep inclines under 40mph, 3rd gear is good depending on
incline from 30-60mph, and 4th above 50 on flats and higher if not.
A manual lockup switch shouldnt be needed if you have the O/D lock out button. IIRC my Dads 05 lets you lockout 3rd gear by toggling the Tow haul button a couple times.

Basically this is how you do a steep pull in a cummins with a 48RE:

1st gear - no lockup, will heat trans, but let it do its thing.

2nd gear - Pull shifter into 2nd gear manually. If your on a long pull at 40mph or less, this will lockup the TC and generate no heat. If it runs at 2500rpm, let it run. Just think about the gas rig you probably had before was at 5000RPM.

3rd gear - If you can maintain speed of 40mph in 3rd, disable the Overdrive on the transmission by toggling the towhaul/od off button. This will lockup the TC about 35mph or so. Again, 2500rpm is no sweat to maintain, or higher if you need.

4th gear - lockup occurs at 47-50mph or so, but only at light thottle, so don't expect an at-speed lockup until 55mph - 60mph on heavier throttle.

The trick is to keep the transmission locked up. Not only does it put the power to the ground better, but the trasmission will cool off if its hot, and stay cool afterwards.

My 96 used to get the trans fluid very hot at high altitude pulls with my camper, now with the ability to lockup 2nd, 3rd, and 4th gear, I can tow up anything with a cool trans.

Joel

When going down a mountain pass, I down shift to 2nd to save the breaks. Does the tran. heat up in doing this? Don

joelabq wrote:Basically this is how you do a steep pull in a cummins with a 48RE:

1st gear - no lockup, will heat trans, but let it do its thing.

2nd gear - Pull shifter into 2nd gear manually. If your on a long pull at 40mph or less, this will lockup the TC and generate no heat. If it runs at 2500rpm, let it run. Just think about the gas rig you probably had before was at 5000RPM.

3rd gear - If you can maintain speed of 40mph in 3rd, disable the Overdrive on the transmission by toggling the towhaul/od off button. This will lockup the TC about 35mph or so. Again, 2500rpm is no sweat to maintain, or higher if you need.

4th gear - lockup occurs at 47-50mph or so, but only at light thottle, so don't expect an at-speed lockup until 55mph - 60mph on heavier throttle.

The trick is to keep the transmission locked up. Not only does it put the power to the ground better, but the trasmission will cool off if its hot, and stay cool afterwards.

My 96 used to get the trans fluid very hot at high altitude pulls with my camper, now with the ability to lockup 2nd, 3rd, and 4th gear, I can tow up anything with a cool trans.

Joel

Thanks Joel, that answered many question I had, but know I have more. I do not have an OD lock-out switch that I know of, just the tow/haul switch. I do have the 48RE. How many times do I toggle it in 3rd gear to make it lockup? I can easily test if it works. Also, are you saying that it is ok to manually down shift the tranny when you are in the above speed ranges that coincide with each gear? I have been too scared to do it in the past because I did not want to rip out the tranny. Or, are you saying start from a dead stop and manually shift up? Thanks again for the great write up.

The better/newer transmissions are more capable of handling those situations than the old style 4 speeds. Never had a problem letting mine do it's thing. Always kept an eye on the temperatures though..

Hey Chas...I notice you have the 2011 PSD (KR even...so jealous!). Have you had a chance to work it yet with the Cat? How does it do? (Sorry to hijack the thread...if only a little.)

Just FYI. Here is a copy and paste of a trip report I made in July 2007 in a diesel truck forum. Maybe you will find something useful:





Trip Report 2007 5.9 2500 MegaCab







Just got back from a trip from Raleigh,
NC to KY, North Platte River, Cheyenne, Snowy Range Pass, Douglass Pass
in western Colorado, Moab UT, Great Basin National Oark, US 6 across
Nevada, 120 into Mono Lake, Death Valley from the west, I-15 pull from
Baker to Las Vegas, North Rim of the Grand Canyon then I40 back to
Raleigh.

I wanted a 6 speed but had to take the auto because of the gear ratios
on the 6 speed. I started the trip with doubts about the truck but I
have to say that it proved itself. I used the Tow-Haul mode and just let
it do its thing. It actually worked very well. Torque converter lock up
in 2nd and Drive is definitely a wonderful thing, going up or down
hill. There were only a few pulls where I could not stay in 2nd locked
and that was because of very crooked roads or slow traffic in front of
me. Even when I was pulling unlocked the heat never got out of hand.

I miss my exhaust brake but with 2nd lock up I got by fine without it. I
would have to tap the brakes occasionally going downhill but never had
any problem with brake overheating because the transmission/engine did
most of the work.

On a downhill I would slow to about 48mph and the transmission would
shift down from overdrive to drive and stay locked up. That makes a
difference.

I drove one whole day with temperatures at 110 with a peak of 113 and
many uphills. The engine ran a little warmer than normal but not by
much. In stock form I think Dodge finally has the whole cooling thing
with the auto worked out. I like the new computer controlled fan. It
comes on much earlier before the water has a chance to get too hot.

I started with 4000 miles on the truck and now have 11,500. I could
detect a difference in mileage between the start and end of the trip. I
drove 60-65 mph for about 70% of the trip, 70+mph for 20% of the trip
and 10% unhooked 4 wheeling or fast local trips.

At the start I have to baby it at 60mph to get 11 mpg. On the last day I
drove 70-75 mph and still averaged 11 mpg.

And the power of the 5.9 325hp motor is awesome. I was constantly amazed
at the inclines the thing would pull in overdrive.

This is my 3rd Cummins. My 2002 6 speed may still have been my favorite
for towing but this is a good truck.

I pulled 18,500lbs for 7500 miles and averaged 11 mpg. All mpg hand
calculated and the computer showed almost exactly 2 mpg too high for the
whole trip. Will the thing ever be correct?

Bobby










________

moo2613 wrote:

Thanks Joel, that answered many question I had, but know I have more. I do not have an OD lock-out switch that I know of, just the tow/haul switch. I do have the 48RE. How many times do I toggle it in 3rd gear to make it lockup? I can easily test if it works. Also, are you saying that it is ok to manually down shift the tranny when you are in the above speed ranges that coincide with each gear? I have been too scared to do it in the past because I did not want to rip out the tranny. Or, are you saying start from a dead stop and manually shift up? Thanks again for the great write up.

If you toggle it, it should go to O/D off on the display if you have the option. You can have the dealer re-flash the ECU to do that if you find 3rd gear lockup more useful then the tow/haul if your truck has no O/D off toggle option. It may have been on the 06 when they started it.

When you manually shift, the transmission wont let you break something. I will manually shift my older 1996 into first gear on a downhill pass for transbreaking and it will only shift down as the speed comes down in the safe RPM zone for that gear. If I'm running in 4th gear at 60, and shift down to 1st gear manually, the transmission will drop to third. As I decrease in speed, as I reach near 30 or so, 2nd gear pops in. As I continue to decrease in speed, 1st gear will drop in around 10-15mph. So if you need to downshift even to climb a hill, do it. The truck won't let you overspeed unless you left it in a low gear down a 10% grade with no breaks or something.

Transmission doesnt really heat up much going down unlocked, but doesn't really stop you much unlocked either. Locked up helps, but diesel is a diesel and transmission braking only does so much without an exhaust brake.

On a side note, others are right on the 5/6 spd auto transmissions as far as letting them do their thing. They work well, but realllllly expensive to beef up or to replace when they go out even compared to the very expensive 4spd counterparts. I'm pretty happy with my 4 speed now, but stock I wanted to shoot it. The 48RE fixes many of the issues the 47RE had, and the shift programming is better as well.

As far as specific advice with those without a way to toggle O/D off, I would just leave in tow/haul, and try out manual second gear and see if thats what your looking for. You can add a manual lockup switch, but without a way to disable O/D, you will accidentally do locked up shifts from 3rd to 4th under load unless you can guess when to let off the throttle when the 3rd/4th shift comes due, and without billet shafts and/or an aftermarket TC, you WILL let the parts escape sooner than later. Not sure I want to do that on a 6%-8% mountain pass.

Do keep the RPMs while locked up above 1800rpm or so on a stock TC/Trans. That is the recommendation so you keep the oil pump in range for holding pressure on the TC clutch.

Joel

Oh, and if you were asking how many times to toggle if your DOES have the O/D off option, you just need to turn O/D off and thats it. It will automatically lock.

To test for lockup step on the fuel peddle a little. If the RPMs only slightly climb (and with speed increasing) then you are locked up. If the RPMs move up fast and the speed only slightly if at all increases, you are not locked up. Most people feel lockup when driving empty as when the truck really starts to gain speed about 50mph or so.

If you really want to see lockup, drive the truck empty to 25mph or so, and pump the fuel peddle a little. Watch the revs go up and down, this is unlocked. Now, maintain 25mph and select 2nd gear manually. Give it a little fuel and it'll feel like it shifts almost. Then hit the fuel peddle and feel the truck increase in speed immediately. That will be lockup.

Joel

Thanks again Joel. The 05 did not come with the o/d off option, so I guess I will leave things be. I have pulled many grades with no issues, just 2 occasions when things got a little iffy. Both times I was going way too slow for the situation and I was too scared to manually downshift.

I think 2nd gear manually selected will do what you want. If nothing else, just slow down while in 2nd gear, the trans will cool off very quickly, and then after the pass is done just upshift and go on your merry way.

Beats pulling over for 20 minutes.

Joel

Is it necessary to leave it in the tow/haul mode when going down the highway around 60 mph?

While you're towing, you should always have it in tow/haul.

in tow haul mode and cruise on will it keep the speed going down the hill? or do you need to use your brakes alot. I have a 2007 duramax, automatic.