Greetings,

I am consider the purchase of a used 2010 Ford F-350 4X4 with the Power Stroke 6.4L V8 OHV & auto trans from a local dealer. From the pics (rails in the bed) it looks like it was set up as a fifth wheel hauler.

The rear end ratio is listed as 3.73. That seems a bit high for a heavy hauler unless they figure that is offset by the high torque diesel. Would this have the Allison transmission? I am guessing the previous owner got rid of it because of the high rear end ratio as it relates to towing a fifth wheel?

Also, the ad states it has electronic shift on the fly - yet I am told that all Super Duties have the manual hubs on the front axles. How does that work? My 3/4 ton Dodge 4X4 was all electronic and there were no manual settings to worry about. You simply turned a **** on the dash and you were in four wheel drive (high or low).

I frequently cross several mountain passes during the winter months and it would be a pain to have to get out and set the hubs each time I left bare pavement and encountered snow....

Thanks for reading.

Mike

 

Greetings Mike and welcome to FTE!

I've moved your thread to the 6.4L Powerstroke Diesel forum for more specific answers from our resident 6.4L gurus.

 

Ok thanks. I noticed it was gone and wondered what happened there for a sec.

Hopefully someone more knowledgeable than I will be able to steer me in the right direction.

Thanks for the welcome.

Mike

 

There is no Allison tranny in that truck. It has a torque shift 5 speed. Good tranny, computer controlled and rated to tow 1k more then the zf6 (6 speed manual). The ESOF in these have auto hubs. They work using vacuum so when you turn the *** it works just like your dodge but unlike your dodge if the hubs don't lock for some reason you can manually lock them. I'm not familiar with the 6.4 and what gearing it came with or what is best for towing but someone else will be in to help.

 

So which position would you leave those hubs in? I think there are two positions if memory serves correct...

 

Leave them in auto. Also its a good idea once a week or so to turn them from auto to locked and back to keep everything moving smoothly. This way if the hubs don't auto lock you wont have to fight them to do it manually.

 

To add to the conversation, the information is right on. The manual turning of hubs can come in handy if you are already stuck and can't get moving a bit.

The truck most likely was used as a tow vehicle. I have 3.73's myself and those are good gears for towing and decent mpgs when you learn the sweet spots.

And the tranny is solid and dependable.

Drive the truck and drive it for several miles if they will let you. Before you crank it up be sure to check all the fluids, pay attention to the degas bottle. Ensure it is in the proper range.

Look over all the hoses for leaks and look down at the frame where the radiator mounts. Look for rust or any leaks.

At 65K before I were to buy it I would insist on a tranfercase and differential fluid change and a tranny flush as part of the deal.

 

Thanks to all for the replies.

From what I have been able to learn thus far, the system uses vacuum to engage and disengage the hubs when in auto mode. Some owners have reported problems with their defrost settings when in 4WD mode.

Anyway, I guess it must be a good system since they are still using it.

By the way, what is a degas bottle?

Also, this vehicle has less than 12K on it which made me wonder why it was traded in with such low miles.

Thanks for reading/responding.

Mike

 

Yes Vacumn is used to turn the hubs. The issue is if there is a leak then your hvac will default to defrost. So that is how you know.

Degas bottle is the coolant bottle. Diesel it is called a degas because it is actually part of the cooling system..not just an overflow.

I would not be surprised of the early trade in so the person could by new.

 

One big thing to do is to have the dealer run. obtain, or show you the OASIS report on it. I wouldn't fear this truck as I would an older 6.0 but the OASIS will show any repairs made to the truck under warranty and it will give you an idea as to whether or not there were any persistent recurring issues with it.

 

Thanks to all for the responses.

I looks like my search will begin anew as this one has been sold.

Timing is everything........

 

The 4WD auto hubs use vacuum to operate. There is a small electric vacuum pump to provide the vacuum since a diesel doesn't produce engine vacuum. Vacuum is not used for anything else, all HVAC controls use electric actuators.

The 4WD hubs provide a manual lock position which is helpful if the vacuum auto lock function fails. The vacuum lines feeding the hubs are a bit vulnerable so they can get damaged.

The degas bottle is similar to the coolant overflow/expansion bottle on a gas engine, however it has active coolant circulation through it. This is where you dip the test strips to test for coolant nitrite leves, and important maintenance item.

The new generation emissions controlled diesels (all brands) are significantly more complex than the older diesels and they do *not* tolerate neglected maintenance.

Key maintenance items for the 6.4:

• Oil and oil filter changes every 5k miles. Use only Motorcraft or Racor filters.
• Fuel filter changes every 10k miles. Use only Motorcraft FD4617 or Racor equivalent filter set (not obsolete FD4609).
• Coolant nitrite testing at least every 20k miles. I recommend testing at 5k since the test strips are cheap and testing only takes a couple minutes. Add VC-8 additive if the nitrite is getting low.
• Coolant flush with VC-9 and refill with new coolant every 60k miles.
• Transmission flush and refill and filter replacement every 60k miles. Avoid the early 2008 models with the external transmission filter.
• Transfer case fluid change every 50k miles.
• Dana rear axle fluid change every 60k miles.

Additionally drain the HFCM water separator monthly. If the drain starts to slow down you have parafin globs building up in the sump which must be cleaned out. Use fuel additive at every fueling, Ford PM-22a/23a or Stanadyne.

Avoid bio-diesel at all costs. The 6.4 is rated for 5% bio max, and all information points to even 5% being problematic. Some stations, notable Love's truck stops are known to sell 5% bio without labeling the pump as such - avoid them. Some states where bio-diesel producers are politically connected have mandated bio-diesel use, in some cases at higher than the 5% max for a 6.4. Know those problem states and plan your trips accordingly to avoid fueling in them.

Low mileage trade-ins probably are due to either:

• The previous owner was not prepared for the higher maintenance requirements of a high performance diesel engine.
• The previous owner bought too large a truck for their needs and downsized when fuel prices went up.

 

How much weight will you be towing? Whether the truck has 3.31s or 3.73s they are rated to tow ~15,000 lbs depending on configuration. You can't get any higher ratio than 3.73s in a SRW truck, and those were only available in '08! '09+ only had the options of 3.55 or 3.31 for the SRW trucks.