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alternator fault ?


lansalot

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Hi

Am checking out a 1991 vogue 3.9 EFI and it has a wee electrical problem. When the engine is revved, various lights on the dash flicker on. Don't really know about regulators and such, nor really where it is. Can anyone advise what the case is likely to be here please ?

Thanks

A

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Obvious stuff..

As it happns on revving and I assume not at constant revs, I suggest you check the alternator drive belt tension.

If it seems tight, then scrub some chalk onto the belt surface.

If the tension seemed OK, the belt was not obviously oily, and the chalk fixed it then probably all is OK but it might indicate that the alternator bearing is on its way out. If you are allowed, slacken off the belt and see if the pully has movement or spins freely.

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Thanks, but the belt isn't slipping I think as it's not just the battery light that comes on. Will check that though, thanks !

Apparently, previous owner (for yes, I bought it :)) had it in garage at one point and she thinks they said rectifier/regulator may be faulty...

Any idea how easy this is to replace or diagnose ?

(Presume multi-meter will show it over-volting or something...)

Cheers

A

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Alternator in mine was playing up a while ago, headlights were flickering in sync with revs. Voltage was erratic between 12-16v. Took it off and put it in to Dave Riach for testing, no fault found. Turned out to be a loose ring terminal inside the alternator (under the plastic cover) - vibration was making it make/break.

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What are the various lights that are coming on?

This sounds more like chaffing wires somewhere to me if the various lights are for different fused circuits etc.

Over voltage from the alternator will blow bulbs and other electrical items, under voltage should not induce warning light bulbs as they are not controlled by the ECU

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OK, thanks for that. Haven't taken delivery of the vehicle yet, but it sounds like it may be a simple electrical fault instead then. As you say, over-volting probably shouldn't produce the symptoms I'm seeing. Last time I was out there however, I noticed a little device that looks like a suppressor(?) bolted to one of the coil terminals, and it had rusted completely through. This may perhaps be something to do with it, but I think probably not.

Device in question looks like this:

DBC2000.jpg

More pressing matters at the moment however in that the engine/tbox mounts in my defender snapped at the weekend while giving it far-too-large :o

Cheers

A

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Ouch - sounds painful :P

That there be a condenser - as fitted to points ignition systems. Its intended to filter out voltage spikes from the primary winding of the coil. Mine ran fine without one for a year so i wouldn't think this would be causing bulbs to flicker.

The mounting lug needs to be clean metal and bolted to a clean earth on the inner wing for it to work.

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