Voyager - Differential Fluid

1990 Grand Voyager SE - 4 speed auto. 120K miles.
Does the differential fluid in this vehicle need to be changed
periodically? how often? My user manual and the Haynes manual
are silent on this topic.
Where are the drain and fill bolts located?
Should I get the fluid from the dealer?
Thnx,
tcl

On Fri, 29 Jul 2005, tcl wrote:

> 1990 Grand Voyager SE - 4 speed auto. 120K miles. Does the differential
> fluid in this vehicle need to be changed periodically?

The differential is lubricated by the transmission fluid, which, yes,
needs to be changed periodically. Use ATF+3, *NOT* Dexron or any other
fluid.

"tcl" > wrote in message
ps.com...
> 1990 Grand Voyager SE - 4 speed auto. 120K miles.
> Does the differential fluid in this vehicle need to be changed
> periodically? how often? My user manual and the Haynes manual
> are silent on this topic.

You must drop the pan to change the fluid. Many transmission
shops can WELD a plug to the transmission pan once you get
it off, so that you can more easily drain it in the future. Do NOT
use any other kind of plug, and make sure the one they weld in is
the type that you use an Allen wrench to get out, and that does not
project out past the bottom of the pan.

Also, you should check the transmission computer, and if it is the
original, non-flashable computer, replace it. The replacement is
part# 4796122 for a 1990-1991 minivan transmission on a
3.3L or 3.8L engine, and 4796121 for a 1989-1991 minivan with
a 3.0L engine. You could probably find one easily in a wrecking yard.

Ted

Ted Mittelstaedt wrote:

> "tcl" > wrote in message
> ps.com...
>
>>1990 Grand Voyager SE - 4 speed auto. 120K miles.
>>Does the differential fluid in this vehicle need to be changed
>>periodically? how often? My user manual and the Haynes manual
>>are silent on this topic.
>
>
> You must drop the pan to change the fluid. Many transmission
> shops can WELD a plug to the transmission pan once you get
> it off, so that you can more easily drain it in the future. Do NOT
> use any other kind of plug, and make sure the one they weld in is
> the type that you use an Allen wrench to get out, and that does not
> project out past the bottom of the pan.

But since most manufacturers recommend channging the filter along with
the fluid, the drain plug offers precious little advantage and is just
something to get knocked off and cause you to lose your oil and then
shortly after your transmission. Just loosen the pan bolts and pull
down the lowest corner of the pan. The oil will drain almost as neatly
as if you had a drain plug.

Matt

Ted Mittelstaedt wrote:
> "tcl" > wrote in message
> ps.com...
> > 1990 Grand Voyager SE - 4 speed auto. 120K miles.
> > Does the differential fluid in this vehicle need to be changed
> > periodically? how often? My user manual and the Haynes manual
> > are silent on this topic.
>
> You must drop the pan to change the fluid. Many transmission
> shops can WELD a plug to the transmission pan once you get
> it off, so that you can more easily drain it in the future. Do NOT
> use any other kind of plug, and make sure the one they weld in is
> the type that you use an Allen wrench to get out, and that does not
> project out past the bottom of the pan.
>
I have just drained and refilled the transmission fluid 3 weeks
ago. I replaced the filter as well. I used ATF+3 purchased from
the dealer. I gather by the responses that the transmission fluid
serves as differential fluid as well, so there is no separate
differential fluid to replace. And it's indeed quite some work to
drop the pan, clean up the pan and the magnet, re-seal, etc..
A drain plug would have been very handy (if you do not plan to
replace the filter). Thanks for the tip.



> Also, you should check the transmission computer, and if it is the
> original, non-flashable computer, replace it. The replacement is
> part# 4796122 for a 1990-1991 minivan transmission on a
> 3.3L or 3.8L engine, and 4796121 for a 1989-1991 minivan with
> a 3.0L engine. You could probably find one easily in a wrecking yard.
>
Hmm... the tranny was a reman one put on in around September 2000.
But the transmission controller module was not replaced. Should I
replace the computer, or just has its software upgraded would
suffice? Thanks for the info on part #'s. Where is the transmission
computer located? can I easily check the part #, or I need toi take
it to a shop to check?
> Ted

Even if you do drop the pan and replace the filter, the drain plug would
still have been handy since it would prevent much of the mess of dropping
the (full) pan. This (cost?) decision seems to drive customers toward the
"dealer power flush" approach thereby leaving all that debris in the bottom
of the pan and the dirty filter to contaminate the new fluid. I personally
don't know what they were thinking when they saved the dollar or two by not
adding a drain hole/plug.

Bob

"tcl" > wrote in message
oups.com...
>
> > "tcl" > wrote in message
> > ps.com...
> I have just drained and refilled the transmission fluid 3 weeks
> ago. I replaced the filter as well. I used ATF+3 purchased from
> the dealer. I gather by the responses that the transmission fluid
> serves as differential fluid as well, so there is no separate
> differential fluid to replace. And it's indeed quite some work to
> drop the pan, clean up the pan and the magnet, re-seal, etc..
> A drain plug would have been very handy (if you do not plan to
> replace the filter). Thanks for the tip.

On Mon, 1 Aug 2005, Bob Shuman wrote:

> Even if you do drop the pan and replace the filter, the drain plug would
> still have been handy since it would prevent much of the mess of
> dropping the (full) pan. This (cost?) decision seems to drive customers
> toward the "dealer power flush" approach thereby leaving all that debris
> in the bottom of the pan and the dirty filter to contaminate the new
> fluid. I personally don't know what they were thinking when they saved
> the dollar or two by not adding a drain hole/plug.

The decision was made for the 1964 model year, long before there was any
such a thing as a "dealer power flush". I agree that a drain plug is nice
to have, but adding one is so easy that I don't see it being worth griping
about.

"tcl" > wrote in message
oups.com...
>
> Ted Mittelstaedt wrote:
> > "tcl" > wrote in message
> > ps.com...
> > > 1990 Grand Voyager SE - 4 speed auto. 120K miles.
> > > Does the differential fluid in this vehicle need to be changed
> > > periodically? how often? My user manual and the Haynes manual
> > > are silent on this topic.
> >
> > You must drop the pan to change the fluid. Many transmission
> > shops can WELD a plug to the transmission pan once you get
> > it off, so that you can more easily drain it in the future. Do NOT
> > use any other kind of plug, and make sure the one they weld in is
> > the type that you use an Allen wrench to get out, and that does not
> > project out past the bottom of the pan.
> >
> I have just drained and refilled the transmission fluid 3 weeks
> ago. I replaced the filter as well. I used ATF+3 purchased from
> the dealer. I gather by the responses that the transmission fluid
> serves as differential fluid as well, so there is no separate
> differential fluid to replace. And it's indeed quite some work to
> drop the pan, clean up the pan and the magnet, re-seal, etc..
> A drain plug would have been very handy (if you do not plan to
> replace the filter). Thanks for the tip.
>
>
>
> > Also, you should check the transmission computer, and if it is the
> > original, non-flashable computer, replace it. The replacement is
> > part# 4796122 for a 1990-1991 minivan transmission on a
> > 3.3L or 3.8L engine, and 4796121 for a 1989-1991 minivan with
> > a 3.0L engine. You could probably find one easily in a wrecking yard.
> >
> Hmm... the tranny was a reman one put on in around September 2000.
> But the transmission controller module was not replaced.

Bad bad bad!!! Unless, perhaps, at some time in it's past life it had the
trans computer replaced? But if it's the original you got to get it
replaced! The original one has bad programming that will make the
transmission wear out faster.

> Should I
> replace the computer, or just has its software upgraded would
> suffice?

If it is upgradable, then having the software upgrade done is
equivalent to replacing it. But the original computers (ie: tcms)
were NOT flashable.

> Thanks for the info on part #'s. Where is the transmission
> computer located?

It is real easy to find. Open the hood, look at the left top of the
firewall. There's a box there with a big cable, lots of wires, bolted
to it.

Here's some pics off Ebay:

Here's the original one:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=7988658086

It's kind of hard to see but notice how ALL sides of the box are SMOOTH.
The
connector in the center is where the wire bundle goes.

Here's the newer one:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=7988652932

Notice on the left that it is FINNED. See also among the fins the 4 metal
tabs?
Those are heatsink tabs. Flashable TCM's that are pre-1996 have FOUR of
those
heatsink tabs. TCM's that are POST 1995 have SEVEN tabs and WILL NOT WORK.

Basically, ANY flashable TCM that is pre-1996 will work in your van AFTER it
has been flashed to the correct firmware for your model year and engine
size. The
TCM must have the "pinion factor" set for your vehicle, as well as be put
into
a "quick learn" procedure. You can get refurb TCM's from the aftermarket or
the dealer, with the correct firmware, (but the pinion factor and quicklearn
will
not be set) or you can find a used one in a wrecking yard (they are not
uncommon)
and take it to the dealer to be checked for firmware load and pinion and
quicklearn.

Also, you pretty much need to go to the dealer for the firmware load since
the
dealers are the only ones that have the equipment as well as the firmware.
Around
here they charge $80 for labor if you were to drive your van in with a
wrecking
yard TCM on the front seat, ready to update and install, and have them do it
for you.

Tranny places that deal with these transmissions regularly usually get TCM's
from refurb houses that are correctly firmware loaded for the vehicle,
and simply use a professional scantool to set the pinion factor and
quicklearn.

Also, wire in cavity 49 of the tcm connector must be CUT when installing
the new TCM.

> can I easily check the part #, or I need toi take
> it to a shop to check?

The part number is on a tag that is on the bottom of the unit, use a mirror
and read upside down and backwards.

> > Ted
>

"Matt Whiting" > wrote in message
...
> Ted Mittelstaedt wrote:

>> Do NOT
> > use any other kind of plug, and make sure the one they weld in is
> > the type that you use an Allen wrench to get out, and that does not
> > project out past the bottom of the pan.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>
> But since most manufacturers recommend channging the filter along with
> the fluid, the drain plug offers precious little advantage and is just
> something to get knocked off and cause you to lose your oil

Matt, please explain how you knock off a welded-in plug that does not
project out past the bottom of the pan. That would be an interesting one.

Do you really enjoy shower baths of ATF? :-)

Ted

Ted Mittelstaedt wrote:
> "Matt Whiting" > wrote in message
> ...
>
>>Ted Mittelstaedt wrote:
>
>
>>>Do NOT
>>>use any other kind of plug, and make sure the one they weld in is
>>>the type that you use an Allen wrench to get out, and that does not
>>>project out past the bottom of the pan.
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
>>But since most manufacturers recommend channging the filter along with
>>the fluid, the drain plug offers precious little advantage and is just
>>something to get knocked off and cause you to lose your oil
>
>
> Matt, please explain how you knock off a welded-in plug that does not
> project out past the bottom of the pan. That would be an interesting one.

I've not seen a plug that didn't extend past the surface of the pan. Do
yoy have a picture of one of these plugs that you can email to me?


> Do you really enjoy shower baths of ATF? :-)

I don't know as I've never taken one. I find it fairly easy to
carefully pry loose one of the low corners of the pan and let the oil
come out. Changing the oil filter on my K1500 is a lot messier than
dropping the tranny pan.


Matt