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Un Canadien Errant
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Could running without a speedo cause a jumpy tach and dead battery?
OK, so a bit of a random one. Could running the car (1980 SC) without a speedo cause issues similar to a faulty alternator/voltage regulator?
Last week I pulled my speedo to have the odometer repaired. While it was out, I ended up going away for the weekend - about a 4hr drive up the coast. Car was absolutely fine on the way up, and driving around town on the Saturday. On Sunday, about 2hrs into the drive I noticed that the tach was occasionally swinging wildly from zero to redline, and the radio was turning itself off and then back on randomly. Sure enough, when I eventually stopped for fuel (luckily I was only a few minutes from home at this stage), the battery was flat. Called a tow truck and had it jump started. I replaced the battery the next day - the original was 7 years old, and figured it was probably 'due' regardless. Unfortunately the symptoms returned today - swinging tach, and battery dead after about an hour of driving. The speedo was still out at this stage. I've now (finally) got the speedo back into the car, and the battery on a charger overnight. Meanwhile I've been doing some reading... and the symptoms are pointing to a faulty VR and/or alternator. However, before I wade into testing and possibly repairing the alternator, I'd like to get the opinion of the forum. Is it possible that the lack of speedo could have been causing these symptoms? Bit of a long shot, I feel - and probably just coincidental that the alternator decided to die while the speedo's out, but still.... thoughts? Al
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Alan ---- 1980 911SC - 'Brian' |
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08-08-2012, 04:12 AM
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Wer bremst verliert
Join Date: Jan 2005
Location: Toronto, Ontario
Posts: 4,767
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I forget, is the alt warning light in the speedo on an sc? If so, what did you do with the blue bulb?
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2007 911 Turbo - Not a toy 1985 911 Cab - Wife's toy 1982 911 3.2 Indiash Rot Track Supercharged track toy 1978 911 3.0 Lichtbau toy "Gretchen" 1971 911 Targa S backroad toy |
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08-08-2012, 04:14 AM
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Registered
Join Date: Apr 2010
Location: New Orleans, LA
Posts: 1,493
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no. i did it for weeks while mine was being repaired.
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1982 911SC, Mocal oil cooler, Bilsteins, Carrera tensioners, backdated heat, factory short shift, Seine gate shift, turbo tie rods, pop off. 2005 Mercedes-Benz C230 kompressor sport 6-speed (daily driver) |
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08-08-2012, 04:20 AM
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Un Canadien Errant
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Quote:
John, alt light is in the tach...
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Alan ---- 1980 911SC - 'Brian' |
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08-08-2012, 04:42 AM
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Registered
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Just a thought, the ground jumps from the back of one gauge to the next. Is there a chance you did not maintain a ground through the instruments?
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Ed 1973.5 T |
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08-08-2012, 05:21 AM
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RETIRED
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Best to check the alternator output while running the engine.
Does the alt light come on and/or stay on when turning the ignition to on and starting/running? The bulb is part of the circuit.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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08-08-2012, 07:19 AM
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Un Canadien Errant
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The light will occasionally turn on at low revs, blipping the throttle makes it go out.
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Alan ---- 1980 911SC - 'Brian' |
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08-08-2012, 12:29 PM
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RETIRED
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If you have a volt meter, check the output at the terminals when running. Should be 13-14 volts. ....12.5 at rest, 13 ish at idle higher when revved.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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08-08-2012, 01:08 PM
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Registered
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Sounds like your alternator is dying but not yet dead, same symptoms as I had. Change it.
Ian |
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08-08-2012, 01:15 PM
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Brian
The Other Woman
Da cab
