Clearing Fuel Guage Fog Without Removing Glass

[Discseven]

Been living with foggy fuel & temp guages for quite some time. Lately, the fog has thickened to the point of now being intolerable. So... last night I read a few threads and decided it's time to dive into this.

Below you can see what I'm looking at. Fuel is worst. Temp comes in second place. Tach and other guages to right of tach are fine. Fog starts to roll in as soon as engine is started and AC is on. Takes about 3 minutes to get to what we're looking at (below) with AC on. (1980)




2 different perspectives to the wiring behind fuel guage:






Fuel guage is now out...




Post I read last night suggested that to remove glass from a guage, the face ring needs to be very slowly pried out. I started this and with nothing to get leverage on, chewing the case up was the result as seen above. On to plan "B"...




By using one tight clamp and one loose clamp, this could provide the needed leverage to work the face ring off. It's not happening... and I know better than to force old parts without the right tools --- nothing good comes from doing so. This needs a press of some sort. But don't have one and am not going out to find it. The alternative way in...




Through the back door. Glass is not going to be easy to reach going this way but it's doable.




A look at fuel guage itself. (Oil guage looks very similar.) Note the fade of the florescent paint on needle. Would have been nice to have red-orange floro paint on hand to touch this up. Would have saved a return trip.




I'm very concerned about screwing the face plate up going to the glass ass-backwards. Older parts (34 years here) can be unpredictably delicate. Am using a dry swab and moving it around with a bendable Q-tip, prayers included.

TO BE CONTINUED

[Discseven]

Cleaning the glass continues...



Above, with the swab removed, film on right side of glass now stands out against cleaner glass on left. But with a dry swab, the film is being moved about and not entirely cleaned up. This is not going to work.




Am now using small piece of paper towel with a touch of alcohol on it. Bendable Q-tip is used to move paper towel around on glass. This cleans the glass very nicely... and so far I haven't screwed anything else up.




During last night's foggy reading I also came upon "the solution" being to put desiccant in affected guages. Desiccant being a substance that moisture adheres to --- adheres to as opposed to absorbs. This packaged stuff gets tossed in closets and storage places to keep things dry. Open the package and eyes tear and the smell is noxious.




The desiccant is parcel-packaged to tuck into guage.




Parcel in place. Perhaps this stuff is overkill. (What do ya think Bob?) I'm open to whatever works. (I can see someone in the distant future getting inside this guage! Perhaps I should include a POISON warning.)




Car's been running for 5 minutes with AC on high... ample time for fog to roll in...

It worked --- notice temp / oil press fogging... and fuel guage is crystal clear (when before droplets would be forming inside fuel guage glass at this time.)

Some posts said cleaning inside of glass in a guage solved the problem. Another comment said desiccant was the answer. (I'm leaning toward the removal of the film inside the glass being the primary solution.) Should there be a deterioration of performance as in the fog recurring, I'll comment when and if it happens.

[Alan Lindquist]

Nice solution. Thanks for sharing how you did that with the "first do no harm" attitude.

[stormcrow]

Karl

Your glass is going to fog up again - you must be getting moisture inside the front somewhere. Getting back to removing the front bezel. I used a 1/8" jewlers screwdriver and worked it around the edges - I didn't take any pics when I did it but it was easy to do.

The lip on the bezel is turned in so you have to proceed very slow to at least get the edge straight up - moving no more then an 1/8" at a time.

It can be done and the nice thing about it is when you re-install the bezel you can turn in the end in a couple areas - just enough to keep it from coming off.

[cabmandone]

Nice solution. This is on my list of rainy day things to do.

[Discseven]

Originally Posted by stormcrow

Karl

Your glass is going to fog up again - you must be getting moisture inside the front somewhere. Getting back to removing the front bezel. I used a 1/8" jewlers screwdriver and worked it around the edges - I didn't take any pics when I did it but it was easy to do.

The lip on the bezel is turned in so you have to proceed very slow to at least get the edge straight up - moving no more then an 1/8" at a time.

It can be done and the nice thing about it is when you re-install the bezel you can turn in the end in a couple areas - just enough to keep it from coming off.

I agree there's moisture causing the fog Stormcrow. What's curious is the fog occurring consistently to the left side guages in our 911s --- not just mine. Why isn't the moisture in the right side guages? Right side guages are not sealed as far as I know. To the point of successfully removing the bezel as you have...

Does your bezel & case look like the below? If so, what did you get leverage on? (I did use a very small screw driver... 3/32" blade.) Also... what's age of your guage? (I worked on mine for a while and my end conclusion was the bezel & case were fused from age.) If you would pull your guage and take a posting-shot of the bezel & case for us that would be most appreciated Stormcrow.

[tharbert]

I'd consider an anti-fogging treatment, something like Rain-X while it's apart.

The desiccant is a good idea if the gauge is a sealed unit. If there is a constant source of moisture, it'll absorb to capacity then be of no use.

[GH85Carrera]

Originally Posted by Discseven

Cleaning the glass continues...

Parcel in place. Perhaps this stuff is overkill. (What do ya think Bob?) I'm open to whatever works. (I can see someone in the distant future getting inside this guage! Perhaps I should include a POISON warning.)

I doubt anyone in the future that opens the guage will think, look someone packed in some candy for me! Nom nom nom.

[stormcrow]

Karl

The problem I had was the same as yours. What I found was water was seeping in on the drivers side hood seal where the hinge attaches. Once I solved that problem and other minor water leaking problems the issue went away.

[Discseven]

Originally Posted by tharbert

I'd consider an anti-fogging treatment, something like Rain-X while it's apart.

The desiccant is a good idea if the gauge is a sealed unit. If there is a constant source of moisture, it'll absorb to capacity then be of no use.

Good idea with the Rain-x Tharbert. I just did my Temp / Oil Press guage... so I'm a little late for this idea

On the desiccant... that's what I thought but decided to give OVERKILL a go.

[Discseven]

Originally Posted by stormcrow

Karl

The problem I had was the same as yours. What I found was water was seeping in on the drivers side hood seal where the hinge attaches. Once I solved that problem and other minor water leaking problems the issue went away.

I too had water coming in from the windshield --- from between the seal & glass AND between the seal and car. It was worst on the driver's side... doing the foot drip. Fixed both those leaks a while ago and my guages... still fogging.

[Discseven]

Just went ahead with same procedure for my Temp / Oil Press guage as was applied to my Fuel guage. I regret not seeing Tharberts idea to put a non-fogging agent on the glass before proceeding. Seems like an excellent idea.

Below, some wiring references to Temp / Oil Pressure guage (1980):




Now with a few disconnects made (out of the way):




Have accessed inside of glass through back side of guage (same as was done with fuel guage.)




Above, a look at Temp and Oil Pressure guts.




Cleaning inside of glass in progress. Final inspection ensures no paper towel filaments are left on inside. When installing guts with glass facing down, debris can fall down onto glass... it's good to check inside of glass while making installation of guts.




From girlfriend's "toolbox" ... tweezer with headlight.




Takes about 35 minutes to:

1. Remove Temp / Oil Pressure guage from dash
2. Take guage apart by opening back doors
3. Clean glass
4. Reassemble guage

Majority of time in my case was given to tagging wires before pulling guage from car.




I used to trust my memory. Not any more. (And this nest of wires seemed better to tag than to draw a color-connect diagram for.)




There's another 10 minutes or so to install in dash --- so this procedure can be done in under an hour.

Photo above is after running engine for a while with AC on full --- AC on full only to push temperature difference between cabin and inside of guages as far as possible. At this time --- before cleaning of the glass --- Temp / Oil Pressure guage would have been fogged. So at this moment, cleaning the glass has once again worked. If this doesn't last, I'm back in for another clean up... this time using Tharberts idea of applying a non-fogging agent to inside of glass.

[Uwon]

I only got fog inside the gauge on cold damp days. The A/C never affected it. So I pulled the gauge out an drove in the rain on a cold day. No water leaks but there sure was allot of cold air movement into the interior. I insulated the back side of the gauge with some 3/4" foam made into a boot with some duct tape and installed it from inside the trunk. Problem solved. I think that cold air comes in from below through drain holes in the unibody (especially the cavity between the front wheel well and the door) and around the base of the tank and fogs up the gauge in the coldest corner.
Johan

[NYNick]

My car never sees rain, I have no A/C, it's garaged and I still get it on the left gauges.
NBD.
Nick

[Discseven]

The consistency of everyone mentioning the left side guages being the foggers has kept me thinking about this. Having just gone inside both these guages, I have a theory to suggest...

Fuel & temp guage internals warm up enough to cause a sufficient difference in temp between the inside and outside of these particular guages and so their internal condensation. Tach, speedo, and clock internals do not warm up enough. AC on or off does not matter as long as there's some moisture inside the "warming" guages, those guages will fog provided a sufficient difference in temperature between the inside and outside of the guage. We all experience different levels of fogging due to variables in the internals caused by manufacturing & age, moisture from leaking windshields & hood surrounds or no leaking, different AC induced cabin temps, ambient temps, etc. The small layer of grime on inside of glass in a fogging guage is a catalyst for condensation to form. By removing that layer of grime, catalyst is gone and so no fog inside recently cleaned glass (as I'm experiencing.)

Someone who's an expert in electrical components might be able to tell us if the internals of the fuel & temp guages could indeed produce heat. (Below are those internals with the exception of the oil level gizzmo which looks the same as the others.)

[Discseven]

Still positive report from cleaning inside of glass --- driving through pouring rain yesterday waiting for guages to fog... didn't happen. Just went back into fuel guage to floro paint faded (34 year old) needles:

[Flojo]

great! I love these small genious DIY touch up detailings - THANKS!

[javadog]

Originally Posted by Discseven

The consistency of everyone mentioning the left side guages being the foggers has kept me thinking about this. Having just gone inside both these guages, I have a theory to suggest...

Fuel & temp guage internals warm up enough to cause a sufficient difference in temp between the inside and outside of these particular guages and so their internal condensation. Tach, speedo, and clock internals do not warm up enough. AC on or off does not matter as long as there's some moisture inside the "warming" guages, those guages will fog provided a sufficient difference in temperature between the inside and outside of the guage. We all experience different levels of fogging due to variables in the internals caused by manufacturing & age, moisture from leaking windshields & hood surrounds or no leaking, different AC induced cabin temps, ambient temps, etc. The small layer of grime on inside of glass in a fogging guage is a catalyst for condensation to form. By removing that layer of grime, catalyst is gone and so no fog inside recently cleaned glass (as I'm experiencing.)

Someone who's an expert in electrical components might be able to tell us if the internals of the fuel & temp guages could indeed produce heat. (Below are those internals with the exception of the oil level gizzmo which looks the same as the others.)

Warming decreases the possibility of condensation. It's cooling that causes it...

JR

[javadog]

Originally Posted by NYNick

My car never sees rain, I have no A/C, it's garaged and I still get it on the left gauges.
NBD.
Nick

Wash the car?

JR

[DaddyGlenn]

Originally Posted by javadog

Warming decreases the possibility of condensation. It's cooling that causes it...

JR

Warming increases the amount of moisture the air can hold. But when that moist air contacts a cooler object (the glass) the air touching the glass is now cooler and cannot hold its previous volume of moisture so the excess moisture collects on the glass.

At least that is what my brain put together.