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Post by wannabe on Aug 2, 2021 16:30:18 GMT
My eBay special voltmeter/thermometer (that seems to have been showing a reliable 14+ volts under driving conditions since buying it a couple of years ago) yesterday was telling me that I was only getting 12.8, 12.5, 12, 11.8, 11.5, 11.7, 11.9, 11.7... volts when driving on the motorway, which would increase perhaps 0.5 volts when I dipped the clutch but then come back down again. It has been odd occasionally over the past few months - dipping but then increasing to 14v+ again if I dip the clutch, let it settle, then rev it - but it wouldn't come back up yesterday. I thought it might have been a slipping belt (I still need to swap the alternator for one that doesn't have a worn 'frame' and which would therefore actually be parallel with the pulley on the engine...) but it wouldn't stop doing it. I have a new (secondhand) alternator ready to go on (bought a while ago to resolve the wonky/worn 'frame' issue) so I guess I just need to pull my finger out and do it, but I'd rather know for sure what the issue is. Any thoughts would be very welcome!  |
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Post by atlex on Aug 2, 2021 21:36:57 GMT
double check that the volt meter is still accurate ? have you got a multimeter ? it's a small job to double check.
also check the voltage coming from the alternator itself..
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Post by dadbif on Aug 2, 2021 21:41:52 GMT
Do your lights dim then glow brighter when you rev the car? No? Does it start ok? Get on with life and stop worrying. 🤪🤪
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Post by wannabe on Aug 3, 2021 8:50:27 GMT
double check that the volt meter is still accurate ? have you got a multimeter ? it's a small job to double check. also check the voltage coming from the alternator itself.. I do have a multimeter but I'm not entirely sure how to operate it...  LOL Is it a case of sticking the red bit on the 'live' bolt on the alternator and then sticking the black bit to somewhere on the shell? |
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Post by wannabe on Aug 3, 2021 8:52:08 GMT
Do your lights dim then glow brighter when you rev the car? No? Does it start ok? Get on with life and stop worrying. 🤪🤪 I don't know because my headlights are still broken lol They are also LED, so they are on or off!  I guess I'm worried about less than 12v meaning the battery is slowly discharging instead of maintaining charge? but then as you can clearly see, I am no autoelectrician so may well be making things up in my head  |
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Post by atlex on Aug 3, 2021 9:07:31 GMT
you've got the right idea, set it to volts, red one to the alternator hot side... black one to any old bolt on the shell.
the alternator is meant to put out more than 12v
battery should read around 12.6v without the engine running - terminal to terminal
with the alternator running you should see 14-14.7v depending on where you check.
from what I recall if the alternator puts out less than 14v it isn't enough to charge the battery.
you've got the tools!
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Post by wannabe on Aug 3, 2021 11:38:38 GMT
you've got the right idea, set it to volts, red one to the alternator hot side... black one to any old bolt on the shell. the alternator is meant to put out more than 12v battery should read around 12.6v without the engine running - terminal to terminal with the alternator running you should see 14-14.7v depending on where you check. from what I recall if the alternator puts out less than 14v it isn't enough to charge the battery. you've got the tools! Thanks! It was working just fine previously so hopefully it might fix itself... haha Will see what I can do! |
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Post by Zed. on Aug 3, 2021 12:04:21 GMT
check connections and earthings... or Earthlings  Rich. |
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Post by wannabe on Dec 6, 2021 0:29:25 GMT
Today's latest madness to drive me loopy... 1hr+ journey going out, setting off from stone cold = a strong 14v+ the whole way. 1hr+ journey coming home? 12.5, 12, 11.8, 11.6, 11.2, 10.9, 10.6, 10,4, 9.9, 9.8, 9.7, 9.3, wipers getting very slow, 8.9, 8.6, headlights going dark on the side I'm indicating towards, 8.5, headlights going off when brake lights illuminated, 8.4, headlights (LED) flickering because they're falling out of operating range...  I did look at the belt location quickly the other day when doing the lights. I seem to have that thin layer of 'fluff' on the front of the block, the thing that scrapes off easily and is remarkably like a belt getting eaten over time... so will get a new belt ordered and try to swap the replacement alternator on which has a bracket that's not worn away and sitting wonky. I think perhaps it might either have a 'good day' when the belt grips, or a 'bad day' when the belt constantly slips and volts drop. Either way, the intermittent nature of it and, er, 'inconvenience' of no headlights at 70mph in the dark... means it needs fixing. |
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Post by dadbif on Dec 6, 2021 8:32:54 GMT
Is the belt tight enough? Once things start to slip, the degree of slippage increases as the belt wears. Try tightening it up, or just fit the new alternator, this will hopefully cure both the misalignment and the slipping.
Not the time of year/weather for it….
Good luck
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Post by wannabe on Dec 6, 2021 10:33:42 GMT
Is the belt tight enough? Once things start to slip, the degree of slippage increases as the belt wears. Try tightening it up, or just fit the new alternator, this will hopefully cure both the misalignment and the slipping. Not the time of year/weather for it…. Good luck Thank you! I do have a Jackson Racing Cold Air Intake to fit as well (somewhere in the garage...) to replace the world's worst and oldest cone filter , so I might well do it all in one hit, given the intake crossover pipe will have to come off to improve access anyway! It's been about 9 or 10 degrees recently - toasty compared to the three degrees it was the other week... lol EDIT: Forgot to say, tension of the belt seems to be a PITA / impossible to work out accurately/correctly. Grainger/Haynes says something like 10kg per 1cm of push inwards? But, strangely, my fingers are not calibrated... I know it should be tight enough to not move but it seems very tight anyway and I fear pulling pulleys going out of alignment or snapping shafts or something!  |
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Post by atlex on Dec 6, 2021 14:52:51 GMT
One way to check 'by thumb and/or eye' is to find the longest length of the belt in question. then try to twist it by about 90 degrees (or more) - if it will go more than 90, then it's too loose, if it won't get as far as 90 it's too tight.
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Post by dadbif on Dec 6, 2021 22:15:13 GMT
With an ordinary v belt you should be able to push it down about 1/2” on the longest stretch with moderate pressure.
Bit vague I know but you’ll get the hang of it.
Twisting test is more useful for multi v belts.
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Post by wannabe on Dec 6, 2021 23:33:42 GMT
Thanks, chaps! I'm not sure which bit is the longest stretch lol I got the ratchet out and moved the alternator out some more - felt like really quite a lot actually - and the vertical bit of the belt, from water pump pulley to crankshaft pulley, now feels a lot tighter (about half an inch seems to be what it's moving) and I'm getting better voltages on the readout (12v - 14v) but they still seem variable for no particular reason! They do go up and down a bit with lights / wipers on, but the 'baseline' seems to be whatever it fancies lol I've got a longer run tomorrow to get new tyres fitted (not the ones I wanted but ho hum...) so I'll see what happens. I would have had a longer run today but I had to wait to get it jump started, seeing as it went CLICKCLICKCLICK instead of actually turning over the first time I tried it - I presume because I'd been sucking juice out of the battery for at least half an hour of the previous perilous journey! I had about a 20 minute run so hopefully that will give it enough to start tomorrow. We will see! |
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LOL
le sigh