disassembling tachometer

[MajBach]

Hi again. I have a Faria tachometer that's been giving me trouble. Last year it started sticking at a low rpm - a little bump to the glass would dislodge it. This year, it's stuck pretty tight. I contacted Faria and they said it is no longer in stock but it is serviceable. Rather than send them a cheque for $35 and pay the same for shipping AND have to wait 8 weeks (standard turn-arond time) for them to fix it plus the delay crossing the border, I'd like to fix it myself.<br />I have it off the boat and in front of me. There are four long brass bolts protruding from the back, each held to the casing by a nut. When I loosen these nuts, the bolts become 'wobbly' and I can feel the contents inside free to move. Obvioulsy this is the first step in disassembling it. But, I can't get any further. It would appear the casing 'breaks' apart from the front. I would imagine one bolt holds the needle, one the face, etc. Problem is, I cannot figure how to get under the glass. There is a nice brass ring on the circumferance of the glass that holds the glass down - on the underside of the ring is a lip that is bent over 90 ° such that it appears to hold the plastic housing together. The brass ring will rotate freely but is not threaded. <br />Can this ring be removed? Do I need to? Is it possible to spray the insides with a lubricant that might coat the sticky needle?<br />One more thing, when I loosened the bolts, the needle freed up, but not without a bit of vibration. I re-installed the tach and started the motor. the tach moved properly but the sticky part is still noticeable. I dont think this thing is garbage just yet but I need the next step.<br />Thanks for taking the time to read.<br />Randy

 

[Mark42]

Re: disassembling tachometer

Sounds to me like there is a slight bit of corrossion in the movement. Maybe a little compressed air in the gap you opened up may clean it out.

 

[Silvertip]

Re: disassembling tachometer

Compressed air on a gauge movement is instant death due to the delicate movement. The bearings are probably jeweled but the movement (armature) probably has a tad bit of corrosion on it. Get it apart, and clean using whatever will fit between the armature and field. No lubricants should be necessary (nor are they recommended as it will get sticky).

 

[ufm82]

Re: disassembling tachometer

Gauges are usually sealed at the factory- the glass/crystal/dome is placed on the body on the gauge with a seal and then the bezel is crimped on, sealing the glass to the body. Unless you want to work your way around the gauge with a small screwdriver to unseal the bezel, it's much easier to simply replace the gauge. Now, if you have an older gauge and want the things to match, a repair may be your only avenue. I doubt you'll find anyone who will attempt a repair so you're stuck doing it yourself. I'm guessing the movement needs a drop of lube to free it up and disassembling the gauge may be your only choice. Don't blow air on it- it will ruin the gauge. <br /><br /> Good luck- I've had a 50% success rate on taking gauges apart. <br /><br />UFM82

 

[MajBach]

Re: disassembling tachometer

Thanks UFM - I expected to hear that. Thought I may be overlooking something though. It does look like a factory seal with the ring. I wouldn't hvae used compressed air either.<br />Think I'll try a teflon/silicon lube in the small opening so as to not attract dust. Might get it to work. Good to know though that the factory can repair it and use the same dial/face/trim. This unit is no longer made and is a set.