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tachometer problem mike smith while driving my ' l roadster yesterday i noticed the tachometer needle swinging erratically several times a second it appeared to drop to zero and immediately bounce back to the proper rpm after several minutes the tach stopped working altogether with the needle at zero can anyone tell me if this is indicative of a particular problem with the tach cable or distributor failing that can anyone suggest priorities for troubleshooting or component replacement rebuilding
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Re: Tachometer Problem
re tachometer problem ed jennings first thing is probably a cable problem disconnect at the distributer end and see if the cable is broken or the end loose if that's ok pull the gear out of the distributer if it's damaged remove it before you run the engine again it will either damage the gear on the distributer shaft or can even lock up the distributer it's ok to run the engine with the gear out and the brass plug replaced you just won't have a tach if neither of these seems to be the problem then you will need to pull the instrument cluster and that's a whole different subject from what you describe i would expect to find a broken cable when you replace it be sure it's lubed in accordance with the service manual ie special graphite lube only lube bottom of cable good luck -
Re: Tachometer Problem
re tachometer problem tom freeman my bet would be on the gear at the distributor cable connection disconnect the cable and turn the end of it while someone watches the tach if the tach moves in response the cable is good if not then the cable is probley broken if it is the gear it is fairly easy to replace but this might be a great time to rebuild your distributor the gear stripped on my ' replaced the cable gear and the distributor shaft not a hard job but a great opportunity to overhaul the distributor tomComment
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Re: Tachometer Problem
re tachometer problem jack humphrey advice given by others is solid start with the easy stuff and insure the dist tach drive is working then check the integrity of the tach cable often tach cables die at either the dist or tach end because they've been too loosely inserted the internal cable's squared end gets chewed up and no longer makes a solid no slip inter connect cable can be easily replaced but you'll find current ac delco tach drive cables differ slightly from factory originals locking ring at dist end is gold dichromate finish vs factory original cad plate if cable is intact then you have to go inside the instrument cluster you can either do this yourself read service manual closely for step by step instructions or have done by an experienced professional in major metro areas in the us you can look up ac delco united delco dealers in the yellow pages who will turn key the whole job for you plus you can buy tach speed head internals all calibrated ready to go from them if you want to do the repair yourselfComment
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