Over-excitable alternator

[IPAddis]

Since I've had my cam changed, the voltage gauge on my Griff has gone from a steady position half way betwee 13 and 15 volts to sitting on the 15 volt mark. Not to concerned about this but I also noticed the other night that the exterior and interior lights vary in intensity giving a sort of strobe effect. What do we think, alternator about to pack in? Can you just replace the diode pack or recondition it or are we talking about a new alternator (cost)?

Also, I've noticed that the car doesn't seem to slide sideways when the wheels are spinning as it usually does (err, when I was warming up the tires officer). It seems to be spinning a single rear wheel. The diff has been making noises for a while so I'm not entirely suprised if it is the next thing to go. Can you check the limited slip bit by jacking up the back of the car and in which case does it need to be in gear, out of gear?

Damned expensive hobby this. I'm going to take up chess.

Ian A.

[shpub]

I think it is yes to everything.

As for the diff, jack one side up with car in gear and see how much does it take to move the wheel. Should take a good shove with a hand. Repeat on other side. Also recommend chceking tyres as they mau be flat, devoid of tread. polished, covered in shock absorber oil or any other thing that will reduce traction.

Steve

[IPAddis]

quote:
I think it is yes to everything.

As for the diff, jack one side up with car in gear and see how much does it take to move the wheel. Should take a good shove with a hand. Repeat on other side. Also recommend chceking tyres as they mau be flat, devoid of tread. polished, covered in shock absorber oil or any other thing that will reduce traction.

Steve

Thanks Steve, I presume the alternator will just pack up at some point, charging light will come on and it will be T-10 minutes until the car stops. I'll check my RAC membership. Will it overcharge and blow up electrical things? Is it worth trying to recondition it or do I remember you saying that the rest of it will be pretty knackered as well and hence you should just get a new one?

As for the diff, the tyres are well down on tread (1-2 mil to wear bars) but does that really make a difference? I'll wait until I change the tyres next month before panicking.

[shpub]

That's affimative to everything as well. If the alternator is Fubar'd then get it sorted quickly as it may be generating enough AC to make the DC the car normally expects to knacker the battery and other bits.

As for tyres yes it does. Also road conditions can vary and cause problems.

Steve

[bogbeast]

Yup, same happened to my alternator, it went off the scale to 16+ volts. At first, only infrequently and then more and more.

Found a local auto electrician that recommended one of his recon ones at £60 rather than a more expensive re-build.

Mine was a fairly common Lucas A127 (pre-serpentine engine).

A word of warning. Most of the motor factors I visited were clueless beyond looking in the various re-manufacturers catalogs. TVR not listed….. Best find a local Auto electrician and make good friends with him. You own a TVR after all..

[Guillotine]

if you're changing the alternator, make sure you get the highest spec item.

depending on year they vary from 65 amp to 99 amp!

take the numbers off the top/side (the last two digits indicate rating) and ask for the high spec model

outputs increased due to the higher loads required by later models with double fans-a/c-heated seats etc but for the extra £20-30 quid or so its worth upgrading particularly if you have noticed the following-

lights/ amp guauge dip when fans come on
lights/ amp guage dip when internal blower on

incidentally there are companies in the motoring press that will build a racing item especially for you.
increased output with less weight/drag. bound to be expensive but may be worth it.

just a thought!

[IPAddis]

Superb, so after spending 3 grand on the car in the last 4 months, I'm now faced with a new set of tyres, a new alternator, a potential new set of rear shocks (the left rear doesn't sound well), a potential new diff and I found out yesterday that the knocking noise from the supension was caused by an elongated anti-roll bar mount on the left suspension so I probably need a new suspension wishbone as well.

The car's only done 37,000 miles. Deep joy.

Thanks for all the advice.

Ian A.

>> Edited by IPAddis on Wednesday 7th August 13:45

[shpub]

[quote

lights/ amp guauge dip when fans come on
lights/ amp guage dip when internal blower on

---

Also more commonly caused by a bad earth wire connection - usually the one under the rad at the front of the car.

[Guillotine]

interesting steve i'll look tonight!

ta

[Bob the Planner]

I've not quite got the same problem as Ian, but I have intermiitent brightening of all the lights occasionally. This happens for about 30-45 seconds and then everything returns to normal. It happens about every couple of hours of running.

I assume that this is related to the alternator and/or diode pack. Any body have any ideas as I don't like the idea of everything getting too many volts.

Bob

[shpub]

Combination of bad earths and/or control pack or worse on alternator. Worth addressing sooner or later as it can start to take other components out if the Alternator is supplying too high a voltage or an AC source. Page 254 in Bible 2 gives more details and how I addressed the earthing problem.

[Bob the Planner]

Thanks Steve. The overcharging bit taking out other things is the bit i'm worried about. Added to the list of things that will get sorted at service in a couple of weeks if I don't solve it using the bible

[Bob the Planner]

Earthing checked and all seems ok when checked with a multimeter and the problem went away for a while. The alternator was checked out at the service too.

Last night on the way back from the south coast I noticed the problem again. I will admit that it was the first time I have driven the car any distance and then put the headlamps on. I found that not only did the head lamps brighten considerably for about 6 seconds every 5-6 miles (like having the main beams on !) the instruments brightened and the wipers went mad - 2-3 times normal speed.

I stopped for a bit with the bonnet open - to think through options of how to procede - and on continuing I found I didn't get the problem for about 20 miles. On leaving the car overnight to cool down at my parents the problem did not re-appear for about 90 minutes of motorway driving by which time everything was good and warm.

I reckon its the regulator breaking down when it gets hot. A check with the multimeter is on the cards - check voltage when cold, go for a 2 hour run out and check again. I suspect a reconned alternator is the next course of action - might be cheaper than 2 hours of petrol !