4WD trouble...

bowtie_pasta · June 21, 2002

The 4WD isn't working right on my 84' S10 Blazer.

I shift it into 4Hi or 4Lo and only the rear wheels pull or something. I got stuck in some soft dry dirt the other day.

So I figure I have some trouble w/ the transfer case or front diff. Haven't serviced either since I've owned it (bout 7 years).

Any ideas? I don't hear any crunching or grinding.

P.S. It used to work when I got the truck, we used to climb some pretty nice hills.

June 21, 2002

Does the 4wd light come on?

Check the thermal relay on the front axle. If you get 12vdc on the wire, the relay is most likely the problem. These are a fairly high-fail item in the newer trucks, Easy to change and I think they cost around $50-$100.

MarkD · June 21, 2002

Didn't the 84 have a floor shifter for 4wd?

bowtie_pasta · June 22, 2002

Yeah, the 84' has the shifter on the floor.

Friz, are you referring to my 84' or my 97'?

I own 2 Blazers. Both 4WD.

bowtie_pasta · June 25, 2002

Also, I know the front diff has been leaking a small amount of fluid for some time. Could low fluid cause this trouble?

Stepside Z · June 25, 2002

I seem to remember the older blazers had a vacume acuator. If the line is off or damaged in some way then the front axle will not engage.

bowtie_pasta · June 25, 2002

Hmmm...vacuum acuator, I'll have to look into that. Can anyone confirm this?

mcali17 · July 17, 2002

Yes, it is a vaccuum actuator. Looks like a little ball valve with vaccuum lines coming off of it, it is screwed in on top of the transfer case. These notoriously fail. We even keep an extra one in our 91 Blazer in case it fails during a snowstorm. It is the vaccuum that engages your hubs, that is why when you pull the lever you don't get four wheel drive immidiately like you do with the push buttom. The vaccuum has to build to engage the hubs.