4X4 engaging

I have a 88 S10 blazer that from time to time I hear a growl coming from the right front tire. Shifting into 4high then back to 2 high stops it. My 86 did the same thing. Any thought on how to stop it from trying to engage? The vacuum ?switch? seems to be ok, it just does this when ever it wants. Sometimes 3 times a day other times it won't do it for months.

Thanks for any thoughts,

Delorian

I have a 88 S10 blazer that from time to time I hear a growl coming from the right front tire. Shifting into 4high then back to 2 high stops it. My 86 did the same thing. Any thought on how to stop it from trying to engage? The vacuum ?switch? seems to be ok, it just does this when ever it wants. Sometimes 3 times a day other times it won't do it for months.

Thanks for any thoughts,

Delorian

My 1990 had that exact same problem. I took it to my mechanic and it turned out to be the valve going into the transfer case had got plugged up with crap. There was also a split vacum line. That fixed the problem. Total cost was under $100.

Frogdog's suggestion will probably fix it, but I've seen that happen before on my buddy's S10 and it was a different problem. His wheel bearing was shot and that somehow caused his auto-locking hub to try to engage on it's own. I'm not sure how that did caused it to engage, but once he replaced the hub assembly, it was fine. Like I said, it's probably not that, but you never know.

If the growl was continuous then i would say it was your hub assembly, but this seems to be an actuator issue. There is only one thing that will affect it...it's the Vacuum switch you mentioned, located on the drivers side of the transfer case on the top end. it must be getting stuck open or the spring is getting weak, in order for your front axle to be engaged it needs a vacuum source to activate the diaphragm (located under the battery box) and it is activated by this valve. I would safetly say it's that valve, they are under $50 Cdn and easy to replace, all you need is a wrench. While your at it check your vacuum lines, although this won't cause your current problem, it will cause the front axle to disengage and that is shitty aswell, especially when your knee high in the mud!!! hope that helped.

Thanks for all the info, but I sold the truck in November. I now have a 95 GMC Jimmy. Gota love these trucks!!! I haven't had the problem with this truck yet. It has the push button 4x4 so it might be set up differently.

Thanks again.

If the growl was continuous then i would say it was your hub assembly, but this seems to be an actuator issue. There is only one thing that will affect it...it's the Vacuum switch you mentioned, located on the drivers side of the transfer case on the top end. it must be getting stuck open or the spring is getting weak, in order for your front axle to be engaged it needs a vacuum source to activate the diaphragm (located under the battery box) and it is activated by this valve. I would safetly say it's that valve, they are under $50 Cdn and easy to replace, all you need is a wrench. While your at it check your vacuum lines, although this won't cause your current problem, it will cause the front axle to disengage and that is shitty aswell, especially when your knee high in the mud!!! hope that helped.

Had the same loud noise in 2WD coming from the front right side of my 2000 SLE. Replaced the transfer case vacuum switch for $80. Problem fixed! Thanks for your help!