4kq differential locks ?s

[Robert M]

The actuators are all plastic, except for the rod.  They're a two-chamber 
design, and depending on the position of the switch vac is applied to one 
side or the other.  If you're getting odd lock function, you could have a 
hose problem (not uncommon IME, these hoses are going on 18+ years old :) ) 
or an actuator problem (again not uncommon, see above).  The mech can also 
get sticky, and is likely to be so if one of the other elements fails and 
the mech goes thereby unactuated.

On my first 4kq (an 86 with 195k) the rear mech was just frozen up.  
Shooting it with PB Blaster and working it by hand 200 times was all it took 
to get it to work, and trimming the actuator hoses back about an inch to 
eliminate the split zone helped also.

On both my 4kq's (my current is an 87 that I bought a couple years ago with 
65k on it :) ) there was physical damage to the front actuator.  In both 
cases I was able to remove it (I think it's on the pass side though*...), 
clean it, and JB weld the cracked area.

IME the lights work well.  I've not had one burn out (aren't they LEDs?) and 
on my cars they were a very reliable indicator of actual lock status.  I 
checked them by hand with all 4 wheels off the ground.  Have a helper sit in 
the car and sing "ON!" when the light lights.  Turn a wheel, and then 
actuate the lock by hand.  On my cars the actual lock even coincided 
perfectly with the light coming on.

*getting the front actuator out is a pain- as I recall it's mounted to the 
back side of a protective shield that will be caked with ~0.33"/18+ years of 
accumulated road grime.  10mm bolts I think, three of them.  No other parts 
have to come off, but you'll have to pull some wild contortions to get it 
all out.  MAKE SURE YOU KNOW WHICH LINE GOES WHERE BEFORE PULLING THEM OFF 
:).  Write yourself a note...

Difflocks rule!

hth,
Robert

>From: Shawn Manny <shawn.manny at gmail.com>
>Reply-To: Shawn Manny <shawn.manny at gmail.com>
>To: Ryan Moon <moon at velaru.net>
>CC: quattro at audifans.com
>Subject: Re: 4kq differential locks ?s
>Date: Tue, 26 Apr 2005 10:39:47 -0500
>
>They nipples on the actuators are only plastic, they may break off and
>if they break when the diff is locked it'll stay that way. IIRC the
>center lock is on the drivers side (us spec cars) ontop of the tranny
>under the tunnel. The rear lock id on the drivers side as well on the
>pumpkin. You may also have a short or bad connection making the light
>stay on. Grab your bently and start tracing vac lines, look for broken
>plastic chassis lines and shot old rubber under body lines.
>
>On 4/26/05, Ryan Moon <moon at velaru.net> wrote:
> > I'm curious about the diff locks. They are activated by vacuum, but is
> > it possible for them to stick or stay locked ?
> > Is the front lock mechanism is on top on the transaxle towards the
> > passenger side, where you'd have to remove some of the exhaust to get
> > to it ?
> > The lights on the switch panel in the passenger compartment are
> > activated by switches similar to reverse light switches ? So meaning
> > the light would only come on if the diff is locked? Or the light would
> > stay on if the diff doesn't unlock?
> >
> > Thanks
> > Ryan Moon
> >
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