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Discussion Starter #1
Hello, all!

I am running into a problem with my 1987 Jimmy 4x4 system. When I shift into four-wheel, the t-case engages, but the front axles do not. Went under the hood and found two vacuum lines disconnected. One I plugged into the actuator assembly behind the battery, but the other one, I have no idea where it goes. It looks like there is a piece of green plastic broken off in there, but I can't find anyplace in the engine compartment for this line to go to.

Possibly I am missing a part under there?:confused: TIA!

Tim
 

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TimboGMC said:
Hello, all!

I am running into a problem with my 1987 Jimmy 4x4 system. When I shift into four-wheel, the t-case engages, but the front axles do not. Went under the hood and found two vacuum lines disconnected. One I plugged into the actuator assembly behind the battery, but the other one, I have no idea where it goes. It looks like there is a piece of green plastic broken off in there, but I can't find anyplace in the engine compartment for this line to go to.

Possibly I am missing a part under there?:confused: TIA!

Tim
The one with the plastic in it is probably the breather for your t-case. Mine has a greenish blue plug in it that lets it breath but prevents water from getting down in there.
 

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Discussion Starter #3
Nope, not the breather-that's safe and sound further underneath the truck.
Any other thoughts on why it's not engaging the front axles, if there is indeed only one vacuum line to the actuator?

Thanks again!!:confused:
 

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i always thoguht that was a breather as well, follow it anbd see where it goes
 

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Discussion Starter #5 (Edited)
:idea:
Whoo! I guess that is a breather up there, after all, after doing a search on rec.autos.4x4

I'm not used to this breather-vacuum concept. 20 lashings for me! I'm sure I'll have more questions to follow if I don't figure the rest of this out.
Thanks again.
 

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in my opinion, you should just junk all the vacum opereated stuff and go for the posi-lok, it makes you hubs fully cable operated, no hassles, co to <www.jcwhitney.com>

:evilg: :scary: :evilg:
 

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Discussion Starter #7
I am definitely considering that option! Right now I have to replace the seals in the front diff. (posted elsewhere) I managed to get it to engage with a temporary solution, a vacuum pump that I let rest behind the battery. Works!
 

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that's good, but maybe not reliable, i have heard of alot of people having trouble with the vacum systems and it being very complicated to get working properly(personally, haven't had that pleasure, mine works fine). I have heard great things about the posi-lok and definitly will get around to ordering it... i hope. Also, there are people who have done home brew posi-loks using a hood release cable, other than that, don't know too much else about it. Try checking out my home away from home, S10-exremists, they might have more info than what i know.

hope this helps.
<http://www.geocities.com/extremist_s10/>
 

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Discussion Starter #9
I ordered the posi-lok cable on Sunday. After looking at it and considering the factory setup, it was a no-brainer. Heck, it's a winter vehicle, I wouldn't mind manual hubs but that's not happening.

Now to rip apart the front end and fix my seal leak(s)...which will get done either a) when my temperature isn't 102 or b) some other time! (wishing for solid front axle...grumble:evilg: :scary: :thumbup: :bash:
 

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There's a vacuum valve on your transfer case that controls the acturator. It lets the vacuum pass to the acturator when to move the T case shifter. It goes bad often. Its like a $35.00 piece at the dealer. Sorry I saw this so late but next time mine goes up I'm going the way of the cable too.
 

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Discussion Starter #11
thanks, bad87: I actually did replace that part ($15 at NAPA, the counter guy had the part number memorized!), but my front chunk decided it didn't want to hold together (well, at least the seals), so while I'm investigating that, I'm replacing the cable.

I would've had it done by now but I had the flu for the past week.
 

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so, seeing as the posi-lok is over $100, why is it the preferred fix? Does this part go out often?

The reason i ask, is i think mine is gone as well, it works intermittantly, and today it ate shit altogether, and is not working at all. I found the part at JC whitney for about 130, but if the OEM actuator is 30ish, why not go that route?

Also, in what sequence would you use the posi-lok system, would you lock the hubs before or after you shifted into 4X?

Thanks.
 

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I have a 91 s-10 and had no front wheel drive after engaging the transfer case--I tested the actuator with a hand test pump and that was holding air and I replaced some of the old, brittle vacuum lines with 5/32nds--then I replaced the vacuum switch that sits on TOP of the transfer case--it was a bear to get to, but it helps to disconnect the linkage and drop it down out of the way----I did not price the switch at the dealer but I paid about $15. at autozone---it was a Help item in a blister pack---so now my front wheels are engaging---not sure how long this repair will last--if this does not continue to work I will try and jury rig a cable set up for a permanent fix---
 

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Ok, so I'm hoping someone can give me a quick check-list on what to do: I have an 83' s10 blazer 4x4 w/ a 2.8l v6. Transfer case locks in, but not the front wheels.....I found the actuator, near the battery, but I'm not quite sure how to check it. Any help is greatly appreciated! (It's time to head back out to the woods and start scouting again, I need my 4x4!!!)
 
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