4wd Not Engaging After Axle Seal Replacement

Westlotorn · July 17, 2010

Well I took a 2000 mile trip, it appears that my front diff vent was plugged, the front diff pinion seal and both axle seals started leaking on this trip. No 4wd was used on this trip. This diff has about 15,000 miles on it since rebuid.

The 4wd still worked after the trip but before the seal repair. I replaced the Pinion seal and both front axle seals. No issue with any, all went smooth. I blew out the Vent to make sure it was open and thought I was done.

Now after this job my 4wd won't engage. The transfer case is engaging just fine, 4 lo and 4 hi but the actuator is not engaging the front axles.

Did I displace something pulling the pass side axle? I have not pulled the axle in the past and I suspect maybe something slipped out of place while I changed the seal?

I had both axles out of the diff at the same time, replaced both seals and re-installed both axles. I am thinking I should have done one side at a time?

It all points to the actuator but I think the odds of it quitting on the same day I took out my wrenches for seal repair is small, I suspect I made an error.

I refilled with Amsoil 75-90 Diff oil.

Any experience with this??????????????? Thanks in advance.

Westlotorn · July 17, 2010

I checked the Actuator, I have power and when I power it up I hear the electric motor spin, I did this several times while turning the tire with no engagement.

I guess it still could be the actuator but I lean toward something moving while I had the shaft out.

[email protected] · July 17, 2010

I'd kill to have a truck that when I put it in 4wd low, it only engaged the back wheels. FUN, FUN, and more FUN that would be! A 0-60 time of around 5-6 seconds would be awesome! I never actually heard of a problem, after replaceing a axle seal on the IFS. But, from what you say when you put power to it and it just sits there and spins, sounds like something on the actuator lever is broke, because after awhile of running it should stop.

Westlotorn · July 17, 2010

I must have mis spoken, the actuator motor comes on when triggered by the switch, it runs a few seconds and stops, sounds like it just engaged the diff. If you switch back to 2wd it makes no sound at all but if you wait about 30 seconds you can hit the 4wd button again and it sounds exactly the same, motor spins for a few seconds and shuts off. Sounds like it just engaged the axle. But it is not locked into 4wd, still in 2wd. If you engage 4wd too soon the actuator motor runs for a much shorter period, maybe less than one second. I suspect there is a spring loaded retraction on this? It takes a few moments for it to retract?

[email protected] · July 18, 2010

I must have mis spoken, the actuator motor comes on when triggered by the switch, it runs a few seconds and stops, sounds like it just engaged the diff. If you switch back to 2wd it makes no sound at all but if you wait about 30 seconds you can hit the 4wd button again and it sounds exactly the same, motor spins for a few seconds and shuts off. Sounds like it just engaged the axle. But it is not locked into 4wd, still in 2wd. If you engage 4wd too soon the actuator motor runs for a much shorter period, maybe less than one second. I suspect there is a spring loaded retraction on this? It takes a few moments for it to retract?

So when you have it in 4wd, will the front shaft not turn. If it won't see which one won't let it turn. If the t-case locks it and it won't turn, then the actuator/position sensor in the front diff is broke. And vice-versa for the diff and t-case.

Westlotorn · July 18, 2010

The Transfer case is working fine, power is directed to the front drive shaft if I push the button, 4 hi or 4 lo.

The front diff does not respond when 4wd is selected. It never locks the axles to the ring and pinion. They free spin in either 2wd or 4wd.

The actuator sounds like it is doing its job but no engagement happens.

All was well till I changed the two axle shaft seals which involved pulling both axles out of the housing.

Thanks for any help.

Westlotorn · July 18, 2010

OK, Solution is simple, Don't pull the axle shaft on the Passenger side. Pull the entire passenger side housing, does not take much more time. When you pull the axle alone a flat washer/spacer drops out of place. The axle has a stub on it to center it in the differential bearing, this washer rides on this stub between the axle and the differential bearing.

In my case when I re-installed the axle this washer had fallen down into the axle housing, it was keeping the 4wd actuator from sliding the sleeve engaging my 4wd.

Looks like all will be OK once re-installed correctly. I still need to re-assemble. When all esle fails, read the manual first!!!!!!!!!!!!!!!!!!!!!!!!!!!!! It looked so simple I failed the intelligence test.