Can I fix the tachometer on a 93 Mazda Protege?

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Alyssa

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My tacho is off by about 5 miles, and in cold/moist weather when the engine is still cool, it sometimes makes a horrible squealing/grinding sound that gets quieter when the engine slows. It only seems to do it at highway speeds. Is it possible to fix this problem myself, and is it something that could cause serious problems if left unfixed?
Made a mistake....meant to say speedometer. Also, forgot to add...the needle wiggles when the squealing happens.
 
Alyssa: A tachometer registers how many times the engine makes a complete revolution in one minute. Usually normal car engines idle at 700-900 RPM's (revolutions per minute), and top out at any wheres from 4500 to 7200 RPM's. The speedometer tells you how fast the vehicle is traveling at any given moment. It relies on an input from the transmission output shaft to the speedometer head. That can be either by mechanical cable or by wire. I believe yours is cable driven. When the bearings in the head go bad, you get the noise from the input disc to the receiver cup driven by the cable as you move. Fix is a new speedometer head or take it to a specialty shop that specializes in speedometer repair. A junk yard speedometer from another vehicle of the same make and model would be much cheaper. Taking the dash apart is a bugger though; without a knowledgeable person you could be out of a car for a while. (It would be able to be driven without the dash board hooked up). You could just disconnect the speedometer cable to make the noise stop, but don't send me any of your speeding tickets, because you won't be able to tell how fast you're traveling unless you're familiar with how many rpms. you turn at 70 miles per hour in high gear. If you have a Garmin GPS or NUVI, it can register speed by satellite, and that is very accurate. Cost of a NUVI is less than a junk yard speedometer installed. Lots more advantages too.
 
I am confused.... Are we talking about the tach or the speedo???
ADDED>>>>> ok. i am not sure if the '93 mazda still had a manual speedo cable or not. I am assume it is electric. If it is the sender is stripping out. If it by some chance still has the old style cable then it is stripping out on one end or the other. It wont cause any damage but will continue to get worse until it stops working totally.
 
The tachometer displays engine RPM, not speed. You're thinking of the speedometer or odometer. If it's a cable driven speedometer you can lubricate it w/ graphite.
 
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