Talk Morgan Forums Morgan Sports Cars Morgan Aero 8, 2012< Plus 8, SuperSports, Coupe & Aeromax Fogged Up

During a quick drive at the weekend - reasonably warm, top down, blue skies - my speedo and rev counter became fogged up... very odd. Never had this happen on any car before.

Fogged up to the extent that from the 10 o'clock to 2 o'clock positions I couldn't see the dials at all.

It cleared of it's own accord once home.

Why might this be?

I had this, but only on rainy days. Either turning on the head lights (and hence the bulb in the gauge) clears it as does time. I think it quite common....at least on the older trads.

Some thoughts here (GoMoG).

Caused by humid air in the instruments and a temperature change, the humid air is the result of the the wonderful August weather!

Occasionally a problem here with the Mog if left outside overnight, but in the garage, which is part of the house and although not heated tends to be warmer than outside, it isn't a problem.

The other solution is to live somewhere warm and dry where this is made.

I guess the Morgan dials are more exposed than the dials on any other car I've had - they're fractionally closer to the elements.

I would live in France - happily. Apart from the government bit!

I've had it a few times on my S3 but it always clears itself pretty quickly and no obvious harm done after nearly 8 years!

Happens regularly on my 4/4 in winter.

You are supposed to modify them by drilling holes from the back, are You not?

Even Vulcan Bombers had air tubes to the gauges to keep them mist free !!!

Interesting test today. I can't get out in the Roadster tomorrow for a variety of reasons, so at tea time I fired it up and ran it to temp with the sidelamps on.
All four small gauges steamed up within a few minutes. This seems to indicate that the misting is not related to cold air circulating in the cockpit. Because the garage, although not warm, was about 6 degrees.

Dave it relates to warm, moist, air inside the instrument and the glass being colder. The mist (in effect dew) then forms on the glass. It is exactly the same as taking a cold beer bottle out of the fridge and into the warmer air. The moisture in the air condenses on the beer bottle.

Turning the lights on only warms the air inside the instrument faster than the warmth generated by the electronics alone. The only real solution is to bring the glass up to the same temperature as the warm moist air inside the instrument as soon as possible. A hermetically sealed instrument with dry air inside would also be an answer.

On the Morgans the bulbs in the instrument are incandescent and therefore generate heat. LEDs are not dimmable without complex circuitry.

A hypothetical solution that has been discussed is running warm air in tubes from the heater system. If an aircon is fitted it would work even better as the aircon unit effectively de-humidifies the air.