'95 k2500 4x4 question

hello to everyone
I've got a question concerning the 4x4 system on my truck. I've got a 95 K2500 6.5 TD, still with the manual selector on the floor to choose neutral, 4High , 4 Low or 2 high. When checking if everything worked as snow was coming my way, I put the truck on four stands, all 4 wheels free and put the selector in 4high, trans in D. Rear wheels where propelled, front wheels did not move!! The ingoing axle in the front dif was turning, but that's all. I did see two connectors and a huge solenoid on the front axle, but as I don't have any documentation on my truck I'm in the dark (or just plain stupid :D)

Here's the solenoidhttp://img91.imageshack.us/img91/332...gin2kn7.th.jpg

Could anyone tell me something about this please?

Bye to all Gerard

Sounds like the thermal actuator has gone south (works like a thermocouple, only backwards). Not too uncommon for the earlier IFS trucks. The actuator engages/disengages the front diff. Either replace the thermal actuator, or upgrade it to the later stepper motor type (requires some minor modification and wiring). We had an article on the upgrade some time ago, IIRC. I'll see if it's still available (or Jim could just speak up *hint-hint*).

thanks for your answer DMax, but as I don't have any documentation I need some more explaining....
I can imagine an actuator engaging/disengaging the front dif to avoid having the ingoing axle from the gearbox turning and wearing the diff needlessly when driving in 2H.
Is the solenoid I fotographed the thermal actuator? How and under what circumstances is it powered since the 4x4 selector is a manual stick on the floor?
Anyway, I'm gonna stroll around this section of the forum a bit, and thanks in advance for your time enlightening me more!:)

gerard

I can't view the image. I can see there is supposed to be an image in your post, but I can't see it (even checked it with another computer and browser). When I click on the Imageshack link, the pic isn't there either. Maybe someone else can see it???

The actuator attaches to the diff housing forward/above the axle, about centerline.

The actuator is activated by moving the 4x4 shift lever into 4x (by a switch at the transfer case). Confirm you have 12V at the actuator harness connector when your lever is in 4x. If you have no voltage, the switch is bad, or it isn't getting 12V upstream (fuse, chafed wire, connector). If you are getting 12V at the harness connector, the actuator is bad, (which is most common), or you have an internal mechanical failure (more rare). The actuator disconnects the axle from the carrier in the diff, so the axles are disconnected from the propeller shaft (axles still turn with the wheels, no matter what).

I have a 95 diff with an OEM actuator here I can take a pic of for your ID, if necessary. It'll have to be Monday, though (leaving for the weekend in the morning). There are many others here familiar with this system, and should be able to help you before then. If not, I'll be back.

Your pix is of the Thermal actuator.

These little creatures hav a nasty habit of failing.

As Maverick mentioned, check the wires to that actuator. If there is 12V there then the actuator is toast.

These units have a heater inside and a special solution that turns to a gas when heated. The gas causes the plunger to extend and engage the front differential.

If you have 12V to the unit then just unscrew the thing and head off to the parts house and get a fresh one.

This is a real no brainer to replace. Just apply a little high tack or other suitable sealer to the threads (NOT LOCTITE)

Take all of 15-20 minutes to replace the thing.

The electic servo units are a better device BUTTTTTTTT then best replacement is the Posi Lock cable device thats sold in the aftermarket.

Simple little push pull cable and a few small parts that replace the electric gizmo.

If by chance you dont have 12V (when the key is on and the 4x4 lever in 4L or 4H only) then the issue could be a fuse and or the transfer case switch or wiring.

If the unit worked before then its likely the Thermal unit gone south.

Keep us posted

Robyn

Right! Got all the info I needed! Got to know how it works to find the problem and I do now thanks to both of you! I'll be on it straight away tomorrow morning to check out what the problem is.

Have a good weekend. For us in Europe it is since diesel price seems to drop under 1 euro a litre:D (about $0,80)

bye to all

I posted this web site awhile back for someone else. It will help you in tacking the problem down.http://www.4x4posi-lok.com/inst_tsg.html.

On the floor near the shifter is a picture of the drive train. When you put the lever in 4HI or 4LO the front drive shaft should illuminate. when the actuator actuates the front axle should illuminate. If it doesn't, it didn't work.