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Towing over mountainpasses a problem.

 
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Old 01-03-2019, 05:53 AM
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Sorry, I meant to say air filter. Thanks again
 
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Old 01-03-2019, 08:54 AM
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I see 248 oil temps with no derate of power. It should derate at 250 is my understanding. I run Rotella T6 currently, but in the warmer months I have used M/C 15-40 dino and it did just fine.
 
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Old 01-03-2019, 09:05 AM
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" I was told that it would pull my 40’ 5v at 17500 without a problem."

Just because it can pull it doesn't mean it's advisable. Either more truck (F450) or significantly less load; otherwise stay out of the mountains.
Err on the side of safety.
 
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Old 01-03-2019, 09:17 AM
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Or a f350 drw
 
  #20  
Old 01-03-2019, 09:34 AM
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Originally Posted by cwp03 View Post
I was told that it would pull my 40 5v at 17500 without a problem.
Not sure, who said it but folks seem to confuse the ability to pull a load along a straight line with being equipped for hauling a load in all aspects. Of course, your truck will pull your rig and of course, it can even pull a little more. But that's not saying that your setup stays safe in difficult situations, and that you can fly over mountain passes. There is a good reason why DWR's, F450's, and gross weight ratings exist!

 
  #21  
Old 01-03-2019, 10:29 AM
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Originally Posted by cwp03 View Post
...Trying to decide if replacing front and rear gears to 373:1 would correct my problem.
Biased personal opinion: I do not believe the gain will be even close to worth the cost of swapping out gears.

I think you're on the right track checking out the items folks mentioned to check. If all is good, adjusting expectations may be needed.

I'd be curious if ANYTHING on the truck is non-stock. Even something as simple as the height of the air dam.
 
  #22  
Old 01-03-2019, 01:04 PM
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The other question I forgot to ask is, "Are you running OEM sized tires?"
 
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Old 01-04-2019, 09:48 AM
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The other day I had a large fifth wheel pushing me down a 12% grade. As I pulled out from behind a slow semi I hit the auto engine brake - the transmission suddenly went from 6th to 3rd gear and it was screaming at 3200 rpm. I turned off cruise and turned off engine brake but nothing changed. I had to shift to manual and run it up to 6th gear to get the rpm to drop. It's quite aggravating, but normal.
When going up these kinds of grades, I haven't noticed any drastic temperature changes, but I usually stick at 50 to 60 mph depending on how long the climb is. With 4.10 gearing I can usually stay in 6th gear but sometimes drop to 5th. I don't think the gears you are contemplating represent enough change to help your situation. Low speed climbs with short gears could give you what you are looking for. Or, if you spend a lot of time in the mountains, an auxiliary oil cooler might be in order.
 
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Old 01-04-2019, 09:50 AM
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Originally Posted by HRTKD View Post
The other question I forgot to ask is, "Are you running OEM sized tires?"
Great question! Changing the tire diameter is going to change the final gear reduction ratio - usually for the worse.
 
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Old 01-04-2019, 09:57 AM
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C3PO, if upgrading the oil cooler is something you want to do then keep an eye on this thread: https://www.ford-trucks.com/forums/1...an-answer.html
 
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Old 01-04-2019, 05:08 PM
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Similar truck 3.55 gears and less weight pulling CO & UT passes 50-60 and temp stays 240 or so. I run the Rorella T6 5-40. The Rotella made a noticeable difference in my 7.3 & 6.0.
 
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Old 01-05-2019, 08:41 AM
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Originally Posted by cwp03 View Post
Trying to decide if replacing front and rear gears to 373:1 would correct my problem.
I can understand how a lower gear set would help from a standing start, but not convinced it would help on a pull at speed. If pulling a hill in 4th (or whatever gear) with 3.55s is not giving enough revs, then why not downshift to 3rd (or next lower gear ?? Pulling 3.73s in 4th would virtually give you somewhere around same ratio as 3rd with 3.55s. The only advantage that I would see going with a lower axle gear set is that it would close up the different gear ratios a little, plus the advantage of a bit more "oomph" off of the line.

Please school me if this is wrong.
 
  #28  
Old 01-05-2019, 02:23 PM
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Originally Posted by mtnguy View Post
I can understand how a lower gear set would help from a standing start, but not convinced it would help on a pull at speed. If pulling a hill in 4th (or whatever gear) with 3.55s is not giving enough revs, then why not downshift to 3rd (or next lower gear ?? Pulling 3.73s in 4th would virtually give you somewhere around same ratio as 3rd with 3.55s. The only advantage that I would see going with a lower axle gear set is that it would close up the different gear ratios a little, plus the advantage of a bit more "oomph" off of the line.

Please school me if this is wrong.
A lower final drive gear ratio lets you pull in a higher gear without the trans having to constantly down shift to compensate. This allow for less strain / heat / wear on the tranny and the engine.
3:55 is probably at the upper end of what you could have if towing moderate or heavy or up / down steep hills. 3:73's are better but 4:10's are the normal towing heavy ratio. I have heard that 4:30's are for really heavy duty pulling.
 
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Old 01-05-2019, 05:35 PM
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Originally Posted by Alleydog View Post
A lower final drive gear ratio lets you pull in a higher gear without the trans having to constantly down shift to compensate. This allow for less strain / heat / wear on the tranny and the engine.
That was my point. Instead of trying to pull a high gear, why not lock out upper gears?? 6th gear with 4:10s, 5th gear with 3.73s, or 4th gear with 3.55s might give you close to the same engine RPMs. The overall engine to wheel gearing would stay close to the same using the transmission instead of the final axle gearing.

When towing at 55 mph in hill country, I will lock out 6th to save shifting. When doing the 7 to 8% mountain grades around here, I will use 3rd manually both up and down (with engine brake) keeping around 40 mph. I could go faster in a higher gear, but it is no point when the next curve is posted at 35 mph. I just sit back and enjoy the scenery.
 
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Old 01-05-2019, 07:23 PM
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Exclamation

Originally Posted by cwp03 View Post
Last year I had overheating and power issues with my 2015 f350 srw 6.7 superduty king ranch with 355:1. I was told that it would pull my 40’ 5v at 17500 without a problem. Going over mountain passes I had power and overheating issues. Truck had less than 38000 miles. Even descending with the exhaust brake the transmission would not shift into higher gear as it leveled out of the grade. Has anyone had these issues? Am I expecting too much and overloaded?

The 2015 RV and Trailer Towing Guide indicates that you’re overloaded, perhaps by several thousand pounds. To complicate matters, the maximum trailer weights are based on the XL trim level, no unnecessary options, no cargo, and no one on board except for a 150 lbs. driver — in other words, all of the fine print stuff. Higher trim levels, other options, realistically sized driver and passengers, and other cargo reduce the maximum trailer weight spec. And, cooling capacity is reduced by thin air at high elevation.

Less cargo, emptying the holding tanks, lower elevation, lower transmission gears, temporarily turning off the A/C, and slower speeds when climbing may help. Regearing the axles from 3.55 to 3.73 may be a solution to consider.

Ford has dramatically improved the 6.7L Diesel engine performance specs over the past few years:

MY2015: 440 HP / 860 lb.-ft
MY2017: 440 HP / 925 lb.-ft (+7.5%)
MY2019: 450 HP / 935 lb.-ft (+8.7%)

Is there an engine “retune (reflash?)” that might help?

HTH,
Jim / crewzer





I suspect that most specs above [except for note (6)] are pre-SAE-J2807 standard.
 

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