Hello,


On my 1985 F250 diesel c6 automatic I can choose 4 high with no problems but I can't select 4 low unless the engine is off. Then it slides in to low with no issues at all. I am following all the instructions that the manual has regarding using 4x4. I use the truck in 4x4 regularly so this is becoming more than inconvenient.

Any input here would be appreciated!


Many thanks.

 

Is your truck auto or stick?
If its stick try putting the transmission in neutral, if its an auto put it in park. That should prevent any rotation of the trans output shaft.

 

You're not alone! I got my 1985 f250 last year and also cannot shift into 4WD low unless the engine is off. Mine is gas and automatic (I believe the C6 tranny) and won't shift into low in park or neutral. Mine is primarily used for snow plowing on my hilly property so I just keep in low while plowing and it hasn't been a big issue but I would like to know why it doesn't shift the way it should.
Hope someone has the answer!

 

Chuck,
Which TC do you have?
Have you tried shifting into low on level ground with the brakes applied and no strain on the parking pawl?

Pressure on the transfer case can come from the engine -or- the driveshaft.

Another thing to look at is the TC shift linkage.
A little lube and working it back and forth will make the action a lot smoother.

 

Jim,,
Good suggestions! I'll try those out and post results. As to which TC I have - If you mean manual vs. electronic, mine is manual. If you mean specific model I don't know but assume the info is on the case itself so I should be able to find it.

 

It's automatic - sorry I forgot to include that.


C6. I will get the transfer case info today.


I have tried shifting it in neutral or Park and it only goes into 4 low with the most painful crunching noises... can't be good.


Any help here would be really useful.


Thanks for all the replies do far.

 

You are going to have to pre-plan any attempt to go into 4 low. If you are stuck or in a bind, it's not going to go.

If you have a automatic, The best procedure is to get it in 4 hi first. Then put the tranny in neutral, then pull the lever back into 4 low. Don't mess around too much going between 4 hi and 4 low. Between these two the transfer case has a neutral. When you put the transfer case in neutral, you are releasing the hold it has on the tranny. Even though the tranny is already in neutral, there is a chance that it will start turning some when you go through the neutral zone in the transfer case. You might get a little scraping, but it will not be anything serious and it should go right in 4 low.

If you leave the tranny in park, it may work, but the truck can't be in a bind. In other words, putting it in park should not be holding the truck in position. It needs to be on level ground. When it's holding the truck in park, this puts the driveline and the transfer case in a bind, and it will not go in.

You never want the tranny in any other gear when going to 4 low. You will be holding the whole shooting match with the brake pedal, and as soon as you put the transfer case in neutral, this will release the hold on the tranny and it will start turning. After that, you can't even put it in park without it scraping.

 

Hi,


The truck goes into 4 high every time with no problems but getting it into four low is really tough - even after four high has been engaged. Actually moving the 4x4 lever is almost impossible and when it does go in it grinds like crazy...


Thanks all.

 

If moving the lever is impossible, go and free up the linkage.

4Hi is simple because you don't have to pass through neutral in the TC.

Once we know what TC you have it will be easier to figure out what's going wrong.
Hard to understand why there would be any motion transmitted to the TC with the truck in park.

 

What gear is the auto tranny in when you try to go to 4 low from 4 hi? Is the truck moving?

 

Its right on top of the drivers side visor.
Truck must be at a full stop and out of gear to switch to low range.

 

Hi,


Truck is always at a stop and either in N or P. Not my first Ford 4x4, actually, and I have never had this problem. All instructions have been followed, which is why this is so puzzling. I will dig out the transfer case model number and post it, as requested.


Thanks for all the input- please keep it coming as I needed to engage the 4 low today and couldn't without stopping the engine... not ideal!

 

I believe the transfer case is the 1345 Borg Warner.

 

This is really odd.
If you had a gearbox I would think your clutch was dragging.
With the parking pawl engaged it is hard to understand how the engine running can make any difference.

How are the motor and transmission mounts?

 

I am not sure, overall. What are the symptoms of bad mounts? I will check on them...