Why does only one gauge fog up?

[VaSteve]

Originally Posted by john walker's workshop

normal. smoke at start up, normal, g50s rattle, normal, heater could work better, normal, etc. they have quirks.

When a guy that makes his living working on these things says it's normal, I go with it. Happens on my SC as well. I try not to let it bother me. It's an old car, it has it's quirks. My wife's Toyota Van is totally quirk (and soul) free.

[maui44]

My 77S does it on the first gauge on the left. Seams to have something to do with the humidly.

[ivangene]

OK - so I'll go with normal and add another "quirk"

the clicking gauge (sounds like a piece of plastic being broken in 1/2)
happens "sometimes" about once/day to once a month

fricken thing is so strange and I know many people report the exact same thing - weird!!

[Aurel]

Moving from New Jersey to New Mexico fixed the gauge fogging problem on mine (and my wife hair complains also went away).

[msterling]

Originally Posted by ivangene

OK - so I'll go with normal and add another "quirk"

the clicking gauge (sounds like a piece of plastic being broken in 1/2)
happens "sometimes" about once/day to once a month

fricken thing is so strange and I know many people report the exact same thing - weird!!

My clock does that! Mostly on a sunny day. It is the lens expanding. Yep, it is weird. I can tap it sometimes and make it click/snap. HOWEVER, we should have a completely separate multi-year thread about this disturbing subject.

Clock lens clicking. Normal

[Drisump]

My car doesn't leak but being a Targa, me driving it open down to probably 45 degrees and living in the Pacific northwest. I can tell you that if I have the lid off and it's below say 60, the gauges on the left will fog up. I have driven the car in many other environments even desert conditions in cool weather (California and Nevada) and it does seem to make a big difference to the fogging issue (low humidity, less fogging). My car has always been like this and I actually took the gauges out the first winter and let them "bake" over a wood stove for six months...no difference when the lid was off and the temps were low. Cheers

[kenrinc]

My 89' 3.2L is the same. I'm in CA. Fog is on the inside of the gauges and happens especially in colder weather. I've always believed it's just due to the fact that the gauges extended into the front trunk. My gauges were all rebuilt by PA Speedo and the reason I had them rebuilt is that at some point in it's life the condensation on the inside froze and left a weird snow flake like pattern on the inside of the glass. After having them rebuilt I was dismayed to noticed that they still fogged! It's the two far left gauges that fog consistently. Yep, chalked it up to another 911ism.

Ken-

[wolds]

I think that on a cool morning all the gauges have cool dense air in them and that that gauge in particular must have a stream of warm air by it that is causing the air to condense on the warm glass. Just a theory anyway.

[Hugh R]

Its a cold air:warm air thing, just like how a cold glass of water gets condensation of the outside of the glass on a warm day. Cabin is usually warmer than outside, the gauges "see" cold air on the left side of the dash closer to the firewall. Its also, at least on my 84 closer to the little dash vent, so more warm air. You could warm the gauge with a hair dryer to drive out the moisture, but it will be back.

[72doug2,2S]

She's just getting a little hot and bothered since you're hand is on her wheel and your holding the gear. It's normal for her to get a little steamy in the oil end.

[964TurboPro]

It is what is commonly known as a design flaw. If you look under the bonnet, you can actually see the backside of the gauges, which means the metal cases are exposed to the ever changing temperature and humidity of the bonnet, while the glass fronts are in the relatively climate controlled cabin. Over the years, the gauges have become less airtight, humid air gets inside, and you get condensation. And if you can see the backside of the gauges you know about the little light bulbs and can see that they are not airtight. Additionally, you could have an issue with the gauge fronts, which are originally glass, although on some gauges a plastic piece was used instead from the factory!! Either send the gauge to Palo Alto or North Hollywood Speedo and have them replace the glass/plastic, the bezel and get a new rubber seal, should help to end the issue, also the moisture absorbing silica will help on occasion unless, you need a new bezel or gauge front!!

[db_cooper]

Originally Posted by john walker's workshop

normal. smoke at start up, normal, g50s rattle, normal, heater could work better, normal, etc. they have quirks.

Johnny is right...some gauges will fog on the inside. Porsche even had a service bulletin back in the 80s. No real cure..they thought drilling some small 1/32 inch holes in the instrument shell would vent the moisture.

As I recall..that didn't work. The instruments were never air-tight with the bulbs and connections in the back anyways.

[Dr J]

Fogging up of the fuel gage and sometimes the oil gauge- check

[Sunroof]

My original gauge on my 1973.5T (Its over 40 years old) has been showing the "fog" during humidity changes all its life. And it still works fine. Its like my personnel barometer! The fogging has been explained over and over again, but it has been deemed as one of the crazy characteristics of the five-hole dash 911's.

I get concerned when it does not fog up!

Bob
73.5T

[Lyle O]

Another bit of odd gauge reality: my fuel/oil level gauge was foggy/cloudy when I acquired the car-permanently. I took the gauge apart, went to clean the inside of the glass, and found that there was a thin film of elastomer on it, probably for anti-shatter protection. That is what had lost clarity. The only way to fix was to use a razor blade and carefully scrape off the coating. The gauge is perfectly clear now and has never fogged since. Not sure when the glass started getting the coating, but mine is an '87.

[GH85Carrera]

I have had my Carrera for 18 years. I have seen the gauge fogging on once. I have driven it 80,000 miles in those years.

I do autocross mine. Sitting out on a black parking lot on 100+ degree days will dry anything out. We have long hot summers. I wash my car after every autocross but it is parked in the garage every night.

If you are getting the fogging, just drive it in 100+ temps for a summer. It will dry out!

[joe payne]

Originally Posted by john walker's workshop

normal. smoke at start up, normal, g50s rattle, normal, heater could work better, normal, etc. they have quirks.

You hit the nail on the head. These cars are quirky. The more quirks I hear people have, the more normal my car is! In regards to the fog up on two gauges, I believe they're the only two gauges that aren't covered by the pressed board cover that bolts on in front of them and moisture and cold air blow straight to them when you start driving. In the morning my car is like me cranky and doesn't want to move to quick for about 30 minutes.

[markivtruck]

remove gauges one by one and drill a 1/8 hole in the bottom about a inch in to vent gauge be careful not to go in too far put drill bit in drill about 1/4 inch sticking out. go slow

[adias]

For fogging to occur inside the glass it requires warmer air (inside the instrument) to condensate on the cooler glass window. I suspect that when the car starts the electrical current inside the instrument heats up the inside air somewhat. A drilled hole (as others suggested) might resolve this offering a rapid air escape route, but I am reluctant to drill the instrument.

I also see condensation on the leftmost gauge (gas-level/oil-level) on cold humid days. The car is otherwise dry inside a unheated garage. What is peculiar is that the condensation is mostly at the bottom of the circular window. Anyone knows how to properly remove the front surrounding bevel to access the rear of the glass window?

[RSBob]

Originally Posted by jclotz

I put a small desiccant pack (the kind that comes in a pill bottle) inside my gauges and it fixed the problem.

+1. I dropped in two and never an issue.