Hey everyone. I did a test earlier to make sure that my 4WD is working so I can drive in the snow tomorrow. I had my mother press the buttons so I can inspect the actuator under the battery. I noticed that with the car sitting still with the engine running, it only partially engages. Then it seems to engage all the way once the car moves a bit. Same thing with disengagement, although it seems slow to disengage at times. I sometimes have to move it straight forward and backward in and out of the garage (about 20-30 feet) before it fully disengages at times. The transfer case itself locks in immediately (blink of an eye fast). I put it in 4WD and sprayed the cable with a small amount of WD-40, hoping that will help, being careful not to poke a hole in the actuator. I am ordering a Posi-Lok system tonight, but it will be a couple weeks before I get an appointment somewhere to get it installed, so I am stuck with the actuator for now. The 4WD seems to be locking in fine. I used the jack and rotated the driver's front wheel and it only turns 3-4 inches before it starts to rotate the driveshaft and opposite CV axle (Is this "engaged"?). Does the car have to be moving for the front axle to lock in properly and does all this sound correct or crazy? Thanks.

 

Mine locks in just fine (knock on wood). I'm thinking the reason you say you have to be moving is a possible vacuum leak. Moving = the engine is running faster = more vacuum. Try sitting still & lightly revving the engine in Park & seeing if it engages faster. Check for vacuum leaks.

 

That is a very good theory. I thought of that myself. However, I should have mentioned this before, but the engine is ALWAYS at idle when I shift the transfer case, moving or not. It seems that something has to be "lined up" in the front differential or it uses the momentum of the car moving for it to lock in? If I am moving and I need the 4WD or I want to disengage it, I slow down below 10-15 (sometimes below 5) mph, let go of the throttle and press the button. I never make a shift with the engine above idle because I don't want to break anything. I will check for vacuum leaks, but where should I be looking and which lines should I be looking for? If I find a leak, what is the best way to replace it without running all new hoses? Thanks.

 

It still could be weak vacuum to the actuator. It could also be a sticky engagement cable or a slightly worn engagement collar inside the front diff that needs to be in the just right position to engage.

When new, the teeth in the engagement collar come to some what of a point at the major diameter of the splines. They not only are chamfered to the middle, but also each edge of the spline is tapered. This allows for engagement at almost any orientation between the collar and the passenger side stub shaft. As the tip of the splines wear over time, the leading edge wears down past the side chamfers causing a blunt tip which prohibits engagement until the teeth line up precisely.

In my opinion, if it engages each time while slightly rolling, I wouldn't get too shook up about it.

 

Oh wow. What confuses me about all this with the front diff was that we had the have the whole unit repaired/rebuilt 3 years ago because we unknowingly bought this car with a broken shift fork that destroyed the front differential. No 4x4 at all even when the transfer case locked in properly. Dealer charged us over $1000 to fix it. It was there for over 2 weeks over the holidays in 2007. I guess I will solve the first 2 possibilities you mentioned when I get the Posi-Lok system. Thanks for the advice.

 

On my 03, the owners manual says car has to be moving and in neutral less than 3mph to engage 4 wheel lo only. It will shift in into auto 4wd and 4wh hi just by pushing the buttons from what I remember. Could be wrong?

 

Well that makes me feel better about taking a week to do my front diff in the cold. Anyway, it is not splines that engage that look like your normal splines. It is more like a wavy circle with probably around 10-15 "waves" around its circumference. There are two matching "wheels" that are separated by a bushing that directs lubricant to the mechanism. There is a collar that moves over each of these things and effectively locks them together. The fork that you mentioned moves the collar. My mind boggles at how anyone could have broken the fork, but that is besides the point. The fork retracts the locking collar beyond the plane that separates the two wheels. So when it engages, it will first move into a position that it hits the second locking wheel, then it will fall all the way in to the locked position once the wheels are in near perfect alignment. Since there are so few peaks and valleys on the wheels they could be out of alignment by as much as 18 degrees (depending on how many actual teeth there are). There is some play in the spider gears of any differential, so when you are backing up there is sure to be some discrepancy in the rotation of the two wheels. Once it drops in all is well.

A good experiment to try would be to jack up the front end and just squeeze the actuator with your hand with the engine off. It may just go right in. If not, have a friend rotate a wheel just a little bit and it will go in. You will feel each step of the movement like this. If there is any noticeable sticking going in or coming out, then the cable may need to be replaced. If the shop did a good job and properly refilled the front diff you should be all set for a long time.

-William

 

Great! So that also explains why I can rotate the wheel about 18 degrees when it is finally locked in with one wheel off the ground with the engine on in 4HI. I think that it while it is having a bit of trouble engaging, it is finally engaging ok when I need it. I think it is sticking. I have the Posi-Loc on order, so I think this will be problem solved once I get it in. That will completely eliminate the vac system for the 4WD and the original cable. It is basically a Christmas present.

We just got a couple feet of snow here in NY and heavy winds are blowing snow onto roads tonight even after the real storm ended. I actually hit a foot of snow with the right wheels and got it stuck. The wind blew lots of snow halfway across the lane on the road I was on just after a hill that I cannot see over. I was going slow and the car just hit it. Then I was spinning wheels. I put it in 4HI and it took off once it finally locked in within a second of getting on the throttle. The transfer case locked in immediately. Thankfully, all the truck needs is a car wash (and spray the frame and front end) and using rust converter/undercoat on the frame where my rubberized undercoat is starting to peel.

 

7 months of snow a year and the underside of my rig is almost rust free!! They mostly use sand over here.....dosent pertain to your problem though

 

The frame itself is not bad because of oil leaks (rear main and the oil hoses before I had them replaced) covering the entire frame in oil. A few months ago, I scraped it off and hit rusted parts with rust converter and rubberized undercoating. Nowadays, I only go to car washes that have the coin operated pressure washer and I use soap on the body and frame, use the brush on the body only and throughly rinse the entire car (body and frame) several times. Basically, the undercoat buys a couple days for the roads to dry up after a snowstorm so I can wash the salt off. The brake and fuel lines lines are my main concern when it comes to rust. I already had the left front, the entire rear main and the portion of the right front line that is in the left front wheelwell replaced because they were rusted and I was concerned about a third brake failure (brakes failed twice in one weekend during the summer on a long trip because a caliper failed and boiled the brake fluid causing a total failure). I am not sure about the fuel lines, but I know there is no leak. The fuel pump was replaced at the same time as the brake lines because it failed when I ran the tank below 1/4 to allow the shop to drop the tank to do the brake line. It failed in the shop's parking lot of all placed. It drove there, but then had to be PUSHED into the bay.