Christian P Posted March 6, 2002 Share Posted March 6, 2002 Hello folks. Any advice on this would be useful... After a damp autumn of blatting (rather than damp blatting, something entirely different), I found my (standard Caterham) dials would mist over completely soon after start-up, and take up to half an hour to clear. Two questions have been bothering me during the dark months of winter: 1. Is there an easy way to reduce/prevent this effect in the future (I've search old threads and found something about cutting part of the dial body away, but having removed the tacho, for example, saw no obvious part to cut)? and, 2. There's now a nice film of gunk on the inside of the glass. Can I easily dismantle the front of any standard dial to buff and polish the inside of the glass to a fine shine? All thoughts much appreciated. Ta, Christian Link to comment Share on other sites More sharing options...
Phil Posted March 6, 2002 Share Posted March 6, 2002 I have the same problem and have been advised to remove the bulb holder from the back of each gauge and warm from the front with a hair dryer and it should vent out the back. Then when replacing the bulb holder use something like silicon to seal it preventing it from happening again. I will let you know if I decide to try this and tell you if it works. Sorry to hear about the Damp blatting problem, get well soon. Link to comment Share on other sites More sharing options...
Christian P Posted March 6, 2002 Author Share Posted March 6, 2002 Phil, A good plan, though the dials are now clear, having rested over the winter. Trouble is, I'm not convinced that even if the unit was completely sealed that it would prevent re-misting whenever the air/glass temperature difference became too great. I suspect that the best approach is the opposite, i.e. to make the whole body breathable (drill lots of holes?) to ensure the temperature gradient never reaches the point where condensation occurs... Christian Link to comment Share on other sites More sharing options...
Graham Perry Posted March 7, 2002 Share Posted March 7, 2002 There was an article on this in low flying a couple of years ago. Can't remember the exact technique, but I do remember it was simple to fix. I think the guy that found the solution is a ships engineer that had similar problems on the Briney Link to comment Share on other sites More sharing options...
Casbar Posted March 7, 2002 Share Posted March 7, 2002 The technique is to remove the dials, then cut a couple of strips in the casing (plastic, about .5 inch by 1 inch ) the idea is to cut through the plastic outer casing to allow air to get into the inner workings. The problem occurs because, the case of the dials gets warm, but the face gets cold, so by cutting these strips, it equalises the temp. That's the theory anyway. Link to comment Share on other sites More sharing options...
Christian P Posted March 7, 2002 Author Share Posted March 7, 2002 Casbar, Hokey doke. That makes sense. My tacho has a metal body but I suppose making holes amounts to the same thing whether it's plastic or metal. Anyone know whether it's possible to open up the front of the dials to clean the inside of the glass, or am I going to have to live with that? Christian Link to comment Share on other sites More sharing options...
Christian P Posted March 7, 2002 Author Share Posted March 7, 2002 Suppose I should also be asking whether anyone can lay their hands on a copy of the article that Graham's referred to? Link to comment Share on other sites More sharing options...
Nigel Riches Posted March 7, 2002 Share Posted March 7, 2002 Christian I have had some experience of repairing car instruments, having worked in the trade briefly, ventilation is the key, but also some warmth, as for cutting slots in the side of the metal case of a tacho, well it would pay to remove the mechanism first, so, carefully prise the instrument face bezel ring off, using a screwdriver and multiple small twisting movements at the sides of the instrument case, remove the mechanism, cut slots, or holes to your requirements, refit the mechanism, using the screws which would have been removed earlier, place the glass, sealing ring(?), and bezel ring, back on the case of the indicator, carefully press the previously raised bezel ring edge back to something that looks tidy and holds it all together, hopefully, where I worked we had a tool that would "roll" the bezel ring back, this was a ball bearing mounted on a lathe tool, the indicator was installed to the chuck of the lathe and the bezel rolled over by hand turning the chuck, all very hi-tech, dont be tempted to hammer the ring as the glass is likely to break, if the indicator is fitted to a sealed plastic case the trick is to place the instrument in a lathe chuck, and carefully part the cover with a saw blade or some other sharp tool, carry out any work required and then to simply glue the parts back together with adhesive similar to that used for sticking plastic models together, the fogging can be alleviated also by wiring the lights to on all the time the ignition is on, keeps them warm, helps to control the moisture, this a power boat trick, hope that some of this has been useful. Regards Nigel. Link to comment Share on other sites More sharing options...
Jam Mad Posted March 7, 2002 Share Posted March 7, 2002 search the archives, this was fully covered a couple of months back. Link to comment Share on other sites More sharing options...
Christian P Posted March 7, 2002 Author Share Posted March 7, 2002 Nigel, Thanks for the post - certainly has been useful. I shall venture forth this weekend with screwdriver and drill bit in hand. Jam Mad - ta, I'll have another look. Link to comment Share on other sites More sharing options...
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