repairing your Flaky Water Temp Gauge.

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Briano1234
Whats that smell?
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repairing your Flaky Water Temp Gauge.

Postby Briano1234 » Thu Jan 01, 2009 1:27 pm

How to fix your Flaky Temp Gauge.


Temp gauges are somewhat tempramental.
The can go out, or intermittant, and lets face it
It is a really great gauge to have working.

Here are the common causes that I have found.
and the fix's.

Take the cluster out of the dash

Test it apply 9vdc to the back, the negative lead is
on the right, Positive is on the big left stud.

Image

Does the meter deflect, leave it on a bit... does it finally die? intermittant connection.
Take the nuts off the studs, and clean the corrosion off of them retighten the nuts.
Does the meter deflect and stay? Good job, your done put it back in the dash.

Still not deflecting or intermittant?


Remove the large connector from the bottom ofhte cluster and
carefully remove the mylar off the tab.

Image

Remove the light bulbs for the cluster display and
gingerly remove the mylar off the locator pins.

Image


Image


Remove the 8 screws that attach the cluster to the face plate.


Remove the voltage stabilizer.

Image


The Phenolic washer is on the bottom screw next to the speedo


Image


Carefully separate the Cluster back from the Cluster front.

Remove the 3 nuts on the back of the water gauge.

Carefully tap the gauge out of the assembly by lightly
tapping on the studs. Once the gauge is out, place the
remaining cluster assembly aside.

Image


Here is the gauge This is out of a jetta.

Image

Apply voltage to it to see if it deflects.

Image

If you are very careful you don't have to remove the needle, but you have to
be carefull on the next step in removing the rivits.

Carefully remove the needle from the two wires that are holding it.

Image

The Gauge face is help by 2 brass rivets.

Image

File them flush with the base plate, then pry them out from the front by inserting
a small straight slot between the face plate and the Base..

Image

Image

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With the Face plate off, you will see either this:

Image

or

Image

Look at the thing, it is basically a toaster. It uses Nicachrome wire wrapped around
a bi-metalic spring, so as current passes from the sending unit to the gauge it causes
the wire to heat up, and move so that it will make the needle deflect.

Because of the nature of the wire it really should of been spot welded or silver soldered to the
connection points, as the wire gets older it will heat all the way back to the connections
causing corrosion and a cold solder joint. This cold solder joint and corrosion is
what causes the gauge to stop working. So we have to fix it.

Image

Shows the 3 places that I have found to be where the connections have issues.

Using a desoldering tool remove the globbered solder from the attachment points

Image

Image

Carefully scrape the wires with a Xacto, hard to photo while doing. This will remove the corrosion
off the wire.

Now make sure that the wire is fully attached to the studs or solder points.

Applying heat, and solder let it flow, the Studs will get hotter than blue blazes.

As soon as the wire is taking heat and solder give it another few seconds.....

Then remove the heat and cool it by taking a wet rag and touching it to the studs....This will
Quench the heat and stop a cold solder joint.

Now test it.

Apply voltage to the pins does the arm move... yes/no.... if yes you are done, if no apply more
heat and solder. Test it..... till it is correct.

Mix up a tad of Jb-weld and apply it to where the brass rivets were and glue the face plate to the
body.

Reattach the needle if you removed it.

REassemble the gauge in the cluster assembly.

Now is the time to think about a couple of upgrades.

1. Replacing the light bulbs. I use sockets from a Isuzu, Pathfinder or Saturn, with removable
bulbs, I go to the parts store and buy "warning lights" (higher wattage) and replave the bulb. You need
3 of them.

I trim the Detent stop with a knife. Spring the brass pads out a bit.

Image

Now, cafully look at the cluster and "pop" the bulb holder off, it is Heat welded to the
case. Remove the crappy green film. and replace the cover and either melt it back or
Jb-weld it.

Carefully reassemble the cluster front to the back.....
Reinsert the screws.
Reinsert the voltage stabilizer.
Place the mylar over the pins and insert the light bulbs and twist.
Apply voltage to the mylar at the bulbs and make sure they light...if not you
may have to twist them more...Carefully... be gentle.

Now before replacing the big connector. Apply a piece of Electrical tape to the
Pin side of the tab...

Image

Wrap the mylar and replace the connector shell.

Now the last upgrade...... Tie a new ground wire from the chassis to the
large cluster connector (the brown wire). I usually screw a 12 inch wire to the
frame with a self tapping screw after drilling a small pilot hole.
Splice it in to the cluster wire. Heat Shrink or tape the connection.

Enjoy a working gauge........better lighting, and a less flaky cluster.
Briano

Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
You can lead a user to a link, but you can't make him Click.... :screwy:

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Calimus
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Joined: Mon Sep 02, 2002 11:40 pm
What year is your cabby?: 1989
Do you own a Cabriolet?: Yes
Location: Cartersville, Ga
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Re: repairing your Flaky Water Temp Gauge.

Postby Calimus » Fri Jan 02, 2009 2:15 am

Very nice Brian. I think we should get together the next time you have a few ideas like this and let me bring my uber camera with the macro lense. Super close sharp pics. Not downing your pics taking skills, I can see the issue is with the camera itself. Ours did the same thing till we got the marco lense for up close an personal shots.

Not only that, but I'm looking for an excuse to make a trip your way and hang out. :mrgreen:
12' A6 3.0T Prestige
88' Scirocco 16v
05' Yamaha FJR1300

User avatar
Briano1234
Whats that smell?
Posts: 3938
Joined: Mon Mar 21, 2005 6:45 am
What year is your cabby?: 1992
Do you own a Cabriolet?: No
Location: Duluth, Ga
Contact:

Re: repairing your Flaky Water Temp Gauge.

Postby Briano1234 » Fri Jan 02, 2009 9:26 am

Calimus wrote:Very nice Brian. I think we should get together the next time you have a few ideas like this and let me bring my uber camera with the macro lense. Super close sharp pics. Not downing your pics taking skills, I can see the issue is with the camera itself. Ours did the same thing till we got the marco lense for up close an personal shots.

Not only that, but I'm looking for an excuse to make a trip your way and hang out. :mrgreen:


Well it is a older Kodak model..... so no inference taken....

All the cabbies are running really well right now... the Green one was kicking my arse last week, but I finally got it fingered out.
Briano

Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
You can lead a user to a link, but you can't make him Click.... :screwy:


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