Moisture in gauges

[gcbennet]

So I’ve had some moisture appear in a couple of my gauges for about a month now. I didn’t think much of it till I pulled them out to figure out how to dry them and discovered why they were giving me false readings for the last couple of days. They’ve both corroded inside. I thought these M-series gauges were supposed to be sealed from the elements.

 

[NormB]

Two of mine are doing that with much less vapor. Bought a few months back, spoke with seller, just watching to see if more „dew“ shows up. Only there when I‘m driving, fades quickly.

 

[ryanruck]

Two of mine are doing that with much less vapor. Bought a few months back, spoke with seller, just watching to see if more „dew“ shows up. Only there when I‘m driving, fades quickly.

Most all of my smaller gauges seem to do what you're describing. Not nearly as bad as OP's. That would seem to be a major leak with it.

In fact, I've got a brand new temp gauge I installed several months back and it will also fog up slightly after a bit of driving. Even has a dog hair sealed up inside it...

I'm guessing these gauges aren't exactly assembled in clean rooms.

 

[86humv]

Those look like Clark brand.
Maybe the Faria are better.

 

[NormB]

Faria. Faint "meniscus" at bottom of gauge comes and goes.

 

[gcbennet]

Both of mine are Faria as well. I don't know for sure how the water got in there, but I'm assuming between the glass and retainer ring from hosing out the inside of the truck.

 

[Sintorion]

I drilled a small hole at the top of my gauge to let the moisture out.

 

[papakb]

The solution is to drill 2 small holes in the gauge housing and then flow clean, dry air or nitrogen thru them. After half an hour of purging the gauge seal the holes with a dab of silicon sealant.

 

[dmetalmiki]

Two of mine are doing that with much less vapor. Bought a few months back, spoke with seller, just watching to see if more „dew“ shows up. Only there when I‘m driving, fades quickly.

No car or van I ever owned, (old or new vintage or classic ) does that. ALL my U.S. Army Trucks do it. Humph! (And) The 432 and the jeeps Do not.
I was thinking of placing some silica gel crystals in them.

 

[Sintorion]

The solution is to drill 2 small holes in the gauge housing and then flow clean, dry air or nitrogen thru them. After half an hour of purging the gauge seal the holes with a dab of silicon sealant.

I thought about filling the hole with silicon, but figured that since moisture was able to get in before drilling that sealing the hole would be pointless.

 

[papakb]

The moisture is trapped in the housing during manufacturing. If it's a wet day so are your gauges.

 

[riderdan]

I thought about filling the hole with silicon, but figured that since moisture was able to get in before drilling that sealing the hole would be pointless.

You can bake the moisture out of them by heating them up (warm, dry air from a heat gun) and then seal the hole. My understanding of what's happening from similar experience is that if they were assembled in a factory where it was even a little humid, then moisture from the air got trapped inside when they were sealed up. Temp changes will cause this moisture to condense on inside of the gauge. If you drill a hole and then heat it up, the moisture will be driven out and if you reseal the hole while it's still hot you should be OK. As dmetalmiki said, you could put a few silica crystals inside, which would also help capture any moisture.

 

[Sintorion]

Pretty sure that the gauge manufactures are aware of humidity and take steps to make sure that the gauges are dry and sealed during manufacturing. If not, moisture would occur right from the start.