Towing with automatic in overdrive

[dmh]

I have a 1995 F-350 turbo diesel 7.3 automatic. Can I tow 5700 lb travel trailer in o/d? With o/d off at 65 mph, my foot is in it, and
I am turning 3000 rpm. Thank you.

[HighwayPrisoner]

Simple solution, put in D, and let the PSD do its thing, pull. i would suggest a good tranny cooler, like the Tru cool from the dieselsite, a tranny temp guage. I see no reason to spin the motor at 3000 rpm, sure wastes fuel, and unneccesary wear on the motor. If the tranny is tired, invest in a BTS, and solve any tranny issues.

[Gone Fishen]

Like what was said, get a decent trans cooler and install it NOW. Put the truck in the 'D' posistion and go. I let it shift on it's own but I keep the rpm's down to 26 or 28. I then let it upshift at the top or close to the top. I travel at 79 mph w or wo the trailer. Of course I loose mileage at that speed but I bought a diesel to keep up with the big dogs, I was tired of watching and pushing.
BTW, weclome to the site, good information on repairs and maintaince of your truck and engine. Any money saved here is well spent on 'goodies'. [img]/ubbthreads/images/graemlins/grin.gif[/img]

[bansheeboy]

the only time i turn of the od is when i find the truck at just that right place on a hill where it keep's kicking down out of od off and on, then i turn it off but otherwise it's on and runnin. my truck dont like to run anything less then 70 even when i'm towing so od is a must. it's not a problem when it's engaged anyway, it the sliding in and out of gear thats the problem and that can be a problem with any gear not just od... if your pulling and you keep sliding in and out from second to drive every 5 seconds it's working the bands in the tranny way more than they need to be so it's time to shift down to second...same applies to od. if it's not trying for another gear then let it pull...

[wittmeba]

[ QUOTE ]
I have a 1995 F-350 turbo diesel 7.3 automatic. Can I tow 5700 lb travel trailer in o/d? With o/d off at 65 mph, my foot is in it, and I am turning 3000 rpm. Thank you.

[/ QUOTE ]
Id be willing to bet that if your statement above is accurate, you will end up in 3rd regardless. The way you can tell is when towing depress the OD button and see if it downshifts. If it doesnt, what I stated is correct.

Terrain will play a factor too. If level you may get away with OD, but it seems maintaining your speed is more important to you than being in OD.

[trich27]

I have a 02 f250 with 35" tires and pull a 50hp tractor with loader and box blade pretty regular. I run in over drive around the 60 to 70mph range and don't have any problems. The tranny does run a little warmer but that's to be expected. Terrain does play a part,but like stated let the motor do what it is made to do, PULL.

[zmc501]

Keep the OD off until you reach 55mph then hit the OD. If you are on a hill and start to lose momentum, take the OD off when your rpms reach about 1,800 and then let the engine work for you. You don't want the engine to lug up a hill but you don't want it screaming either. Try to keep the rpms around 2- 2,500 on a hill.

[SmokeyWren]

[ QUOTE ]
You don't want the engine to lug up a hill but you don't want it screaming either.

[/ QUOTE ]

If you have a stick shifter, then you have to worry about such mundane things as lugging the engine. But with an automagic tranny in a '99-up PSD, the engine will never lug. The computer that controls the engine and tranny (the PCM) won't let it lug - it will downshift before the engine begins to lug. And I assume that applies to older PSDs too.

So in a nutshell you never have to kill the OD on a 7.3L PSD - except to descend a steep grade. If the load is too heavy for the grade, the tranny will automagically downshift out of OD. When the grade changes so it's not so steep, the tranny will upshift back into OD. The PCM will also not allow "hunting" between the gears, so don't worry about that either.

Personally, I don't care for the automagic downshifts when on cruise control and OD at around 62 MPH, so I usually manually kill the cruise and OD at the bottom of the grade.

[ QUOTE ]
Try to keep the rpms around 2- 2,500 on a hill.

[/ QUOTE ]

Disagree. I drive by the pyrometer and try to maintain 1,200 to 1,250º pre-turbo EGT when towing up a mountain pass. RPM doesn't matter, as long as it doesn't go over the red line (around 3,300 on a 7.3L PSD) or under the power curve of around 2,000 RPM. There's nothing wrong with taking the pass at 3,000 RPM as long as you keep EGT under 1,250º pre-turbo, and the boost under 25 PSI.

[Kanman]

You wont ever hurt a thing pulling in Direct. Might waste a lot more fuel doing so, but it sure aint gonna hurt it.

If you dont have a pyro gauge get yourself one some time. Around 45-50 MPH with truck in OD and TC locked up. Kick the truck into Direct and watch your pyro drop like a stone. Mine dumps 100 degrees when i kick in to direct almost every time.

[Allister73]

DMH, I usually ask the guys lots of dumb questions about the Stroker motor, but in the past, I was a marine diesel mechanic in the service. I will tell you that in some of the high-speed gunboats, SEALS are not nice to them. I was invovled in helping out the US NAVY, being a COASTIE, at some get'em up again jobs. Run a diesel at max rpm for too long, or run it up hard and drop the throttle, you can and will get yourself some extra mainbearing play. I have spoken to Dale at Tymar about this very thing. Marine Strokes are designed to be 2655 rpm runners for 300,00 hours. Run them above that for too long, and I promise you will be headed for grief. These are not four bangers. The crank and con-rods are very heavy. Also, do not forget the spring weight [img]/ubbthreads/images/graemlins/blush.gif[/img] on the valve springs. Floating them as I have seen is really ugly. Lots of weight to be slinging at 3000 rpm for extended time. Just my .02. Drop to direct and slow down, and let your engine live its degined lifetime. Colin

[fullerzone.net]

My first question would be: what does the owner's manual say? You know Ford spends a lot of money on trans engineers and other stuff to figure all this out for you.

[pabrannan]

My ford manual says it's OK unless it hunts.

Paul B