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Any Ideas?


Guest paul091085

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Guest paul091085

Before i start, please ignore my simple explanations, but i am still learning about all this.

 

Ill give you the story so far... a week or so ago, my fan belt started squealing, the battery light came on in the dash and the tacho needle started bouncing. I then changed the belt, it stopped the squealing, but the battery light stayed on and the tacho needle continued to dance about. I then changed the alternator and the battery light went out, but what confused me a bit was that the voltage at battery was the same for old and new alternator (13.23V) but it made the light go off :wacko: . Anyway, since then the tacho still jumps about and the car now seems to be running hotter than usual and i seem to be down on power. Could the loss of power and excessive heat be linked to what ive done with the alternator and bits? It sounds unlikely, but its only since ive changed the bits that i noticed it. I also have a very rattly and noisy clutch now, could that have any thing to do with it?

 

Any thoughts are welcomed :D

 

Nigel- i know you suggested a diode from maplins that would possibly stop the tacho jumping, but when i went in the guy swore blind they didnt sell it! i asked him to look it up on their webpage, but he refused as he was certain they didnt do it. Have printed out the page ready to take in on thursday and wave in front of him

 

Paul

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Feel free to take what I say with a pinch of salt because like you I am new to this.

Does your fan belt drive the water pump? That might explain the overheating, squealing and now rattling. It also might cause the belt to slip not allowing the alternator to spin fast enough. It may even cause the lack of power.

Like I said, feel free to ignore this advise as I have been trying to build a super spec for 7 months and got nowhere.

 

 

Jeremy

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Quite likely. Slip the fan belt off and test that the alternator and water pump both turn freely with no graunching of bearings. Also check for any sign of a water leak at the pump. You may have overtensioned the worn belt to try and stop the squeek before you changed it, thus damaging the water pump bearing. You also need to tighten the belt after a few miles as they stretch early on.

 

Nigel

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Guest stu205
Have printed out the page ready to take in on thursday and wave in front of him

 

 

usually the best way with maplins! jumped up 17 y/olds trying to tell me about a 555 timer :rolleyes:

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Guest paul091085

just slipped the belt off and the water pump does turn by hand quite easily. So i guess thats not the problem, any other things i could check?

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Guest hypermick

Paul,. Im just mulling over what you said earlier in the thread. <_<

 

Longboarder covered most of the things to look for but Im just wondering about the symptoms you have. :(

Looking at the voltages, the battery , with a good alternator should show 13.8 - 14.25 volts, volt meter applied across the terminals, with a fast engine tick-over. If the alternator regulator is cutting in and out properly you will see a definite kick in the meter needle. (best not to use a digital meter for this check since the readings dont lock up fast enough). ;)

Moving on, the symptoms suggest the battery. I say this because the tacho needle movement is dependent on stabilised pulses detected via the ECU module which the alternator wont give from its own output. ie which means you dont want heavily fluctuating battery voltages. We had a vehicle at work which had similar problems to yours. You may find the alternator is trying to bang the charge into an otherwise gradually failing battery.

I think before you go spending any further money, whip the battery down to an auto electrical, or battery and tyre depot an have them do a full discharge drop test on it for any cells which may be faulty. Charge it up, best you can off the vehicle first before taking it.

 

I can confidently tell you that my donor, had at one stage an almost flat battery, which only just started the car and the tacho went wild. A fully charged battery stabilised the whole thing the next day.

Since the fuel air mixture (depending on your set up) is altered by the ECU module your engine is more than likely effectively , (by the nature of the unstable voltage) overheating as a result due to incorrect settings. It would make sense !

 

I have to say, its for the very reasons above I have done away completely with anything on my 2B loom (ECU and horrible fuse box & relays included) which is likely to give rise to these problems, prefering to keep things very simple as an alternative.

 

good luck,..

 

 

Mick.

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Guest elgey7

Another common reason for the voltage stability issue is caused by 1 of the 6 rectifying diodes in the alternator being short circuit. This has the effect of not fully rectifying the 3 phase AC of the Stator to DC.

The end result is an AC (or neg pulse) on top of your DC. this could not hell out of your tacho - more pulses!

 

Mick is correct the normal regulated alternator voltage is commonly 14.2 if 1 diode has gone you will not reach this value.

 

Regards

Colin

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Guest salty_monk

Weird it's done it with both alternators!

 

Check the battery as the output figure is defo low. My mates Tintop had the same low output which he thought was Alternator as battery seemed to be fine (charged well etc) but a new battery cured all the probs.

 

Dan :)

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Guest paul091085

Learnt a valuable lesson today. Always check all possible options when trying to find a fault :wub: . Thought the problem was the alternator, and although it seemed to solve the problem, the real problem was the battery. Got the battery tested and to put it in a nice way, it was ready for retirement. Plugged in a fully charged borrowed battery, voltage across the battery is now 14.16V and the tacho needle has finished jumping about :D.

 

Thanks to the people that suggested checking the battery, such a simple check :wub: .

 

Now onto solving my rattle :(

 

Paul

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