Please Help - Blacktop Zetec blowing alternators

[RemaL]

Ok over the winter replaced our silver top 1.8 Zetec with a new blacktop 2lter. swapped over our raceline sump. using the twin 45's from the slivertop. A basic and simple swap.

But thought after a while we had battery issues as it would struggle to start after a few weeks. replaced Battery but that was not it.

Brother in law brought up a batt charging tool from his work to tell if the alternator was not working. Seemed the Alt had blown, OK chaged it in March. went to a dyno and stoneleigh without a issue. But 1 week before le mans thoguth to double check the Alt is charaging and it had blown the alt again.

Just replaced this alt today, when usinig a multimeater and this charging tool it was again working. we are going to le mans Tues.

Ok I took it out for a run and did no more than 5 miles around town. at no more than 30MPH and got home checked it all and now blown this Alternator. not charing at 14volts as it was before I went out. is now again showing 12.5approx volts when checked with multimeter



Only thing is the alternator is rather hot after this short run, I know its a hot day but we never have had issues with the tiger running too hot

So any suggestions???

[Steve_D]

Sounds to me like you may have the wrong diameter pulley on there and you're over reving the alternator.

Steve

[Paul Drawmer]

As above.

plus (and this is a guess - pse will someone correct if needed):
Did you check the charge voltage at the battery terminals? If it was already fully charged, then the control system will stop over charging. Maybe you should check directly the alternator voltage output.

[RemaL]

I have just put a larger pully on the lat a few months ago because of the over revving I have heard about. went to a 68mm pully from a 54mm pully. But the 54mm pully and original Alt lasted 6 years and 10k. but since the new engine and pully, and a few other things its blowning the alts.

As for the batt fully charaged I kept the lights, 4 hazards on for about 1 hour and was still not charging or more than 12.3v when running.

[singlecoil]

If it's correctly wired, and turning the right way (though I'm not sure it would make a difference with an alternator) and there isn't anything abnormal happening in the rest of the system, it does sound as if the new alternator has simply failed, through some internal cause, and needs to be replaced under the guarantee.

[RemaL]

singlecoil said:

If it's correctly wired, and turning the right way (though I'm not sure it would make a difference with an alternator) and there isn't anything abnormal happening in the rest of the system, it does sound as if the new alternator has simply failed, through some internal cause, and needs to be replaced under the guarantee.

Nothing wrong when running. nothing out of the ordinary. But this would be the second alt in 2 weeks. both charing when the car has been started first time BUT then broke.

thing is we have had issues but not narrowed the, down to the Alternator since we changed the engine over for the new one. added a ciggy lighter socket, and new exhaust

times to short now to take it to le mans BUT looking at it when I get back to see what the hell is up

What would stop a alternator from charging just by running the car for a short time?

[singlecoil]

RemaL said:

singlecoil said:

If it's correctly wired, and turning the right way (though I'm not sure it would make a difference with an alternator) and there isn't anything abnormal happening in the rest of the system, it does sound as if the new alternator has simply failed, through some internal cause, and needs to be replaced under the guarantee.

Nothing wrong when running. nothing out of the ordinary. But this would be the second alt in 2 weeks. both charing when the car has been started first time BUT then broke.

thing is we have had issues but not narrowed the, down to the Alternator since we changed the engine over for the new one. added a ciggy lighter socket, and new exhaust

times to short now to take it to le mans BUT looking at it when I get back to see what the hell is up

What would stop a alternator from charging just by running the car for a short time?

Fault finding in vehicles electrics is a fascinating, difficult and frustrating task. Actually deducing the fault from observation of the symptoms can be misleading. Component substitution is the preferred method, but wouldn't be appropriate here.

So you need to use logic. Assuming that there is a fault (and that you haven't just been unlucky) the fault has to be inside the alternator or outside. "When you have eliminated the impossible, whatever remains, however improbable, must be the truth". In eliminating the impossible, start with the easiest stuff and work through to the most difficult.

So you need to have another look at all the wiring and mounting issues that might possibly having an effect, until you are quite certain that everything is as it should be. If you are certain, you are either wrong, or the fault lies inside the unit, which would indicate that you have just been unlucky.

[RemaL]

More info::

OK so took at friends advice and started the car up, then once running disconected the live from the batt. it kept working?????

checked with the charging tool and mulitmeter when we did this first when the engine was cold and it said it was charging?????

revved to approx 2k with the battery live disconnected and turned on the lights to full beam and hazards and it kept working???

So whats up. once the engine and alt had been on a few mins it then stopped saying the batt was getting charage from the alternator?

So no closer to finding out what the problem is apart from the alt is working, then it's not???

[singlecoil]

RemaL said:

So no closer to finding out what the problem is apart from the alt is working, then it's not???

That sounds like the alternator is failing when it's hot, then sorting itself out when it cools down. Typical faulty electric/electronic component failure. Squirting refrigerant onto individual components to see if the fault goes away is a recognised fault finding procedure, though difficult to do in your case. Do you have an accurate voltmeter in the car, that you (or better still, the passenger) could watch while you are driving? Or failing that have you a decent digital meter you could connect to be able to read whilst driving the car?

[stevebubs]

Are you using a blacktop or silvertop alternator?

Think the blacktop ones may need a connection to the ECU to control the charge (vague memories - may be wrong)

I fitted a silvertop one to mine....

[RemaL]

usng a Lucus LRS 101 alt same as I had in the car for 6 years without issues. got a mate today coming up (suto leccy) to have a look as its got to be the wiring somewhere

[singlecoil]

Be sure to let us know what it turned out to be.

[RemaL]

Will do mate, bet it's something simple. But so close to Le mans I'm pizzed off not being able to take it. even if I find out what it is it's going to be to late to take it due to leaving tomorrow straight after work

[CorseChris]

Is the charge warning lamp working properly? It needs to be present and correct, or you'll get odd behaviour out of the alternator. Basically, the current fed through the warning lamp bootstraps the internal regulator. Sometimes, an alternator will start charging OK if the bulb is blown then stop again if the revs drop too low. Normally not an issue, as the battery will hold it up, the current flowing through the bulb will re-start teh regulator and all is well.

No bulb/blown bulb (or no other form of providing the boostrap current like say a resistor from the igniton feed) and it's gets weird and unpredictable.

Worth a look anyway.

HTH