So I was about to sell my 99 GV 5spd, so I cleaned it out and was taking for a quick drive and figured I'd test out the 4wd, it had been awhile, anyways, no 4wd...  No light, no nothing, so I pull into the garage to investigate, just as I'm driving into the garage I push in the clutch to pull it out of gear, no pressure on clutch and pedal goes to floor!  Hit the brakes to stall the engine and try the clutch again - nothing...!

So in the below pics it appears I found the culprit for the 4wd not working, the air line to the front dif is not connected...  But, the host doesn't fit the line, is something missing?  

Now for the clutch, is it likely the clutch master cylinder or the clutch?  How do I test?  Never done any clutch work on a vehicle before.

Thanks,
-Chad

Uhhh - if I'm not mistaken those two pictures are the right side of the radiator from above - and if I'm right, that's not your 4WD problem - the metal pipe is the freewheel air pump intake line and the rubber hose is the front differential breather and the two are not supposed to be connected to each other.

The diff breather would normally have a dust cap on it and be clipped in those plastic clips to hold it in place.

The air pump outlet runs back down the right frame rail and then along the crossmember to the underside of the differential.

As for the clutch - it could be either or neither - you'll have to check them.  Start by looking at the master cylinder reservoir - does it have fluid in it. and if it doesn't follow it up by checking under the dash and under the vehicle to see if the master or slave are leaking.

Let me know when you're ready to work on the 4WD and I'll give you a hand.

Ah, good to know, I just traced the hoses and saw two disconnected ends and jumped the the conclusion they should go together...  Although it does look like the diff vent hose lost its cover.  I'll investigate the other hose tonight, I've also read the how-to on disassembling the pump to replace o-rings and clear rusty stuff.

The clutch master does have fluid in the reservoir, no leaks I can see.

Thanks,
-Chad

Sometimes the fluid leak is trapped in the "dust cover" of the master/slave cylinder and you have to ease it back to actually see the leak - but if the reservoir is full, then it's probably not leaking - slide under the truck and look at the clutch slave and the end of the clutch fork whilst someone else presses the pedal - if the hydraulic system is operational you should see some movement.

I've heard stories of the clutch release fork "wearing" through at the pivot - I've never seen it happen, but it's one possible cause of the problem you're having - that would be bad news though - it's a lot easier to fix a hydraulic system problem, if it's the clutch fork or anything else in the bellhousing, you have to drop the transmission & transfer case, just to get to it.

As far as the 4WD setup goes, there are a couple of other "quick checks" to do before you consider tearing the pump apart - for example unplug the pump's electrical connector and connect a 12V test lamp between the red & black wires - see if it lights up when you select 4WD (the ignition needs to be on) - that tests most of the control system

OK, so it I've read a bunch more posts and did more troubleshooting and narrowed it down a bit.

The 4x4 pump seems able to provide the correct amount of psi, I can pull the hose from the diff, hold it with my finger and the pump builds the correct pressue and turns off.  When I plug it back in to my diff it keeps running 10 seconds and shuts off, could there be a leak in my diff?

-Chad

Might be a bad o-ring in your diff.

Yeah, figured I was going to have to pull the front diff...  Tons of fun...

-Chad

I don't think there are any O-rings in that diff - the line connects to the free-wheel actuator which is a one piece affair that expands around 3mm when pressurized (one piece in that if you take it apart, you'll probably need a new one) - but yes, the symptoms you describe do point to an failed actuator so in the diff you go.

Also - if I might briefly revisit my earlier post - I had said I'd heard stories of the clutch fork wearing through at the pivot but never seen it personally - well I have seen it now.  I changed my clutch about two weeks back and sure enough the clutch fork is cracked and you can see daylight through the pivot point.

Also - if I might briefly revisit my earlier post - I had said I'd heard stories of the clutch fork wearing through at the pivot but never seen it personally - well I have seen it now.  I changed my clutch about two weeks back and sure enough the clutch fork is cracked and you can see daylight through the pivot point.

Oh dang!  I just crawled underneath mine, reset the rubber boot and WD40'ed the joint, started working again...

-Chad

Hey - if it works, just drive it - unless you have some zillion thousand mile desert crossing planned, why drop the tranny just to inspect it?

I was curious about mine for quite a while, but never touched it until it reached a point where it was engaging a hair above the floor and making shifting difficult.

Just an update, for the front differential not engaging I just ended up going to the junk yard and pulling a matching set of 4.62s from a Vitara to replace the 4.30s in my GV, this solved my problem, never did find out what the issue was with my front dif, but figured at the point I was at it was easier to replace than tinker around...

-Chad