John in NC Posted January 30, 2008 Share Posted January 30, 2008 2004 RT Anyone here have this problem? How hard is it to get into the tach and clean? Link to comment
BeamieToo Posted January 30, 2008 Share Posted January 30, 2008 John, You are not alone here. I have a little condensation at the 4000 rpm position. Don't have fix so I'll wait in line with you for a remedy. Link to comment
Ken H. Posted January 30, 2008 Share Posted January 30, 2008 It's a challenge. The chrome ring around it (not visible in an RT until the dash is off) is pressed around holding together. You have to cut it off, then figure out how to hold the tach back together. The band is not available separately. In an RT where it only the face doesn't show it's a bit less of an issue. E.g. - just glue it. Or you could try taking it out and blow drying it through the lamp bulb holes. But it will likely come back if the lens seal is bad. Or just replace the tach with a new or salvage one. Link to comment
T__ Posted January 30, 2008 Share Posted January 30, 2008 2004 RT Anyone here have this problem? How hard is it to get into the tach and clean? John, I haven’t ever done this on the BMW TAC but sure have on other bikes, boats, & cars with moisture inside the unit or on the under side of the lens.. Find a large water tight container (I use an old 2 gallon glass jar with a large lid),, place your instrument (tac in your case) in the air tight container,, then rig up a way to add a hose fitting to the top of the jar,, then hook that fitting to an air conditioning evacuation pump (vacuum pump),, pump the internal pressure down to as close to a perfect vacuum as you can. Then use a heat lamp,, sunlight,, or other source to raise the jar temperature to about 100-125°f or even a little higher.. That will boil the moisture out of the instrument & leave it moisture free.. Water boils in a vacuum at a very low temperature so will get pumped out by the evac pump after a short time.. This works good on watches with water in them also.. Twisty Link to comment
outpost22 Posted January 30, 2008 Share Posted January 30, 2008 2004 RT Anyone here have this problem? How hard is it to get into the tach and clean? Yeah, my RT tach has it too sometimes. I have learned to live with it as it is too much work to fix it, and it's only a minor annoyance. Link to comment
ShovelStrokeEd Posted January 30, 2008 Share Posted January 30, 2008 +1 on Twisty's method. Do be aware that it will take a pretty long time to get things really dry. Figure about 24 hours under vacuum at around 125F. Beware temperatures much higher than that as it can degrade seal materials, particularly under vacuum. You don't have to really get it super dry like I have to do with the media my gas adsorption equipment analyzes. There, we look to get ALL the water out, vacuums down to 1.0e-6 atmosphere and temperatures in the 300-400 deg C range and it can still take 4-10 hours, depending on the material. Link to comment
John in NC Posted January 31, 2008 Author Share Posted January 31, 2008 Drying the tach under vacuum doesn't fix the problem. I had mine replaced once while the bike was under warranty. I was just wondering if anyone else tackled the job. Think I'll just live with it. Link to comment
ShovelStrokeEd Posted January 31, 2008 Share Posted January 31, 2008 You have tried this? Did you seal the tach afterwards? If not, humidity will re-enter the tach and once in there, any time the dew point inside the instrument gets high enough, the moisture will condense on the lens. It worked for me on my Garmin 2730 although with the high humidity in Florida, I expect it to come back. Link to comment
Quinn Posted January 31, 2008 Share Posted January 31, 2008 Has anyone tried just using a dessicant pack like comes in electronic equipement? I would think that one of those, dried out in an oven first to get it super thirsty, sealed in jar in the sun for a few days would work. Link to comment
4wheeldog Posted January 31, 2008 Share Posted January 31, 2008 I hate to run counter to the collective, but I don't believe that the condensate is water.....I believe it is an oil or silicone lubricant that has evaporated through the instrument. I doubt it will respond to vacuum. Sorry. Link to comment
ShovelStrokeEd Posted January 31, 2008 Share Posted January 31, 2008 Doubtful on the oil or silicone based oil. At normal temperatures (10-40 deg C) they just don't have the vapor pressure to evaporate and then there wouldn't be enough to saturate the interior of the instrument to cause condensation. It's water. BTW, get the vacuum/temperature high enough and oil will evaporate, it will even fraction into its baser components. It just ain't gonna happen inside a tachometer out in the world. Not enough heat and atmospheric pressure is too high. Link to comment
RFW Posted January 31, 2008 Share Posted January 31, 2008 Has anyone tried just using a dessicant pack like comes in electronic equipement? I would think that one of those, dried out in an oven first to get it super thirsty, sealed in jar in the sun for a few days would work. Deccicants are a "double edged sword", so to speak. Silica gel (the usual deccicant) absorbs moisture, but also releases it when heated. So once the tach is in the sun and heats up a bit, the silica gel will release a lot of its absorbed moiosture and everthing will cloud over again. One simple thing to try is heat the tach to (say) 50°C to 60°C in an oven for a few minutes, then let it cool to room temperature. Then repeat this several times. What will happen is that on heating, some of the internal moisture-saturated air will be driven out by expansion, then when cooling, it will draw in some dry room air. The internal humidity will now be lower, allowing some of the internal moisture to evaporate. Repeat the process, and eventually the internal moisture will be gone. A bit tedious, but a vacuum pump is not needed. The original K100 tach/speedo assemblies were really bad for fogging and in 1989, BMW replaced them with a new unit that had a couple of Gore-tex breather vents on the bottom which cured the problem entirely. Link to comment
George Brown Posted January 31, 2008 Share Posted January 31, 2008 2004 RT Anyone here have this problem? How hard is it to get into the tach and clean? Yeah, my RT tach has it too sometimes. I have learned to live with it as it is too much work to fix it, and it's only a minor annoyance. Me Too. It seems to come and go - haven't seen it for the last couple years but not because I did something special -- it just went away. Link to comment
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