Joined:Tue Feb 23, 2010 12:40 pm Posts:3245 Car Details:'79 Camaro, 350 V8 Location:South Bucks
Thanks for the link Malc, that is a nice beasty. 140amp too, a lot more capable than the stock 80-105 one
I put the multimeter on the old alternator when it was out - tested for continuity between the positive out plug on the back and the body and there was a connection, so it looks like there is a short circuit in there. Have kept hold of it and will see if there's anything i can do with it, will give me something to do when it's freezing cold outside lol.
Put the new alternator it, fit like a charm started the car and straight away the volts were over 14v Still got the old battery in, left it to charge to full over night. Have driven it a few times now and seems to be charging. Will keep an eye on the battery and maybe change it out next month when doing the oil and filter changes. Will post some pics up when i'm back home...
Thanks again for all the help
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Joined:Tue Feb 23, 2010 12:40 pm Posts:3245 Car Details:'79 Camaro, 350 V8 Location:South Bucks
Well, looks like this issue is starting to ease it's way back in.
I'm starting to get the thing where the voltage drops when stopping at traffic lights. The idle drops to about 550 / 600 rpm and After about 5-10 seconds goes back up to about 700-800 and the voltage goes back up to 13. When i drive home from work it's lot more noticable as the lights are on (new units from about 2 years ago and have halogens, so likely uses more juice, they are nice and bright). There's always a good 10 minute traffic jam as soon as i leave work and i'm starting to notice the lights dim a little. I normally don't have the radio on, or the heaters, or rear defroster. But soon, will need to have them on.
Thinking that i will start with the headlight relay mod (add in a relay to receive signal from the wiring harness, but have the lights hooked up via direct battery feed through a relay and fuse). I'll document this incase anyone wants to replicate. Normally the current flows out the battery, through the fuse box, into the cabin, through the light switch, back out into the engine bay and finally to the lights. This way it reduces a lot of resistance and takes strain away from the switch. Not sure if it will make a difference to the situation, but worth a try - few £ for relays and terminal connections better than £150 on a new alternator.
Also thinking the alternator may be a bit on the weak side. It's a re manufactured unit as all of the replacements seem to be, so i will look at the Powermaster that Malc recommends, from Summit: http://www.summitracing.com/int/parts/p ... /overview/ Mine is a V belt pulley so instead of this model 47802 it's this one 478021 . I'm waiting to see if Summit will do any Black Friday deals, fingers crossed.
The alternator cable will also need to be upgraded, found some UK suppliers that sell 6 gauge wire and high amp terminals for a reasonable cost, so will measure up and order some of those parts too.
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Joined:Mon Mar 09, 2009 12:13 pm Posts:205 Car Details:1979 Camaro
How much is the voltage dropping when stopped?
What electrical stuff are you running which might be adding to the load that is higher than normal? It may be that now the darker/colder days are here the extra load of lights/heater etc are pushing the system to a limit, in which case you want a bigger alt. I can't say I fully understand it, but I have also heard that going too big may not be a good idea, but better to go for the size you need for the system (Don't ask how to calculate, I don't know that either!)
From the symptoms, it sounds a little like some I've seen where at low revs (idle) the alt isn't spinning quickly enough to charge. At normal engine speeds all is well, so there may be nothing to worry about.
The lighting upgrade you mention is a good option, may improve the lighting output at the same time.
Joined:Mon Mar 09, 2009 12:13 pm Posts:205 Car Details:1979 Camaro
Oh, and I forgot to say, the inside of the alt is relatively simple, and you can get rebuild kits that contain the commonly failing parts.
I took apart my failed Powermaster (140A) to see what was wrong. Can't remember what I found now, but I did buy the kit, but never got as far as fitting it.
May look do to do as part of the restoration, on a wet day when I'm stuck inside.
Joined:Sat Jun 28, 2014 6:55 pm Posts:808 Location:Croxley Green, Hertfordshire
The battery is supposed to keep things running and the alt keeps the battery topped up, if you are relying on alternator power to run you have too big a draw for your battery to cope with or your battery is pickled, as you have been running with a dud alternator your battery will have taken a huge hammering
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Joined:Fri Mar 19, 2010 1:35 am Posts:2566 Car Details:79' camaro road & track day toy. 383 stroker, 5 speed TKO trans, lots of suspension stuff, 13" Vette brakes, 18" wheels. Location:Luton
Quote:
The battery is supposed to keep things running and the alt keeps the battery topped up, if you are relying on alternator power to run you have too big a draw for your battery to cope with or your battery is pickled, as you have been running with a dud alternator your battery will have taken a huge hammering
Yep, most alternators I've ever had go have usually taken the battery with em' ..
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Joined:Tue Feb 23, 2010 12:40 pm Posts:3245 Car Details:'79 Camaro, 350 V8 Location:South Bucks
Thanks for the helpful replies! I made a video to show you how it looks. I took a different route yesterday so less traffic, and also didn't setup a good camera angle, so the dials read a bit differently. For example, in the clip when you see i'm driving the voltage is actually over half way, at 13.5, in the vid it looks like 13. For reference, the bottom of the gauge is 8 volts. I'll try for a better angle today as i'll be taking the traffic route. You can see the dash lights dimming when at a stop.
Not sure if this is just normal behavior? I'm not running any accessories - heater fan is not on, radio is not on. It's only the ignition system running, electric fuel pump, and lights. In the when at idle, my foot is off the brake, just the handbrake is on. You can see the voltage start to climb up slowly. Seems to sit at about 11 / 11.5v bit hard to see.
I changed the battery and alternator together, pretty much exactly a year ago. So the battery is new and i'm sure the guarantee will be 3-5 years on the battery as that's what i've normally seen.
Quote:
you can get rebuild kits that contain the commonly failing parts
Ye, funnily enough i kept the original - they would give me a £25 recore value for giving them the alternator, but i thought well, i'll get a rebuild kit and give it a try too. It's on the list for the winter
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The battery is supposed to keep things running and the alt keeps the battery topped up
ah that's interesting, i used to think that, then i read somewhere that the alternator is what kept the car running, so now i'm confused lol. That's very easily done though.
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How much is the voltage dropping when stopped?
It varies, according the gauge (with the lights on) it usually drops about 2 volts.
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It may be that now the darker/colder days are here the extra load of lights/heater etc are pushing the system to a limit, in which case you want a bigger alt.
I'm thinking along those lines too.. has been ok all of this year, just recently it's starting to happen.
Quote:
From the symptoms, it sounds a little like some I've seen where at low revs (idle) the alt isn't spinning quickly enough to charge. At normal engine speeds all is well, so there may be nothing to worry about.
Ye that sounds like the behaviour. When driving it's fine - once i get out of the 10 minute traffic jam and onto the motorway, i can put the heaters on, radio on and it doesn't go below 13v on the gauge. Then when i come off the motorway and stop at the lights, voltage drops again. That will happen even if the radio and heater have been turned off the whole journey (the exhaust makes for a good radio). That's why i started to think about a bigger alt, as voltage delivery seems ok when driving, but it's only at idle when it's dropping. I'm going to be needing to use the rear defroster soon, and from last year (after the new alt and battery) it did make a noticable drop in voltage - would take off 0.5v easily and after about 30 seconds it would drop another 0.5 (it doesn't stay on for longer, that's a whole other thread...).
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Joined:Fri Mar 19, 2010 1:35 am Posts:2566 Car Details:79' camaro road & track day toy. 383 stroker, 5 speed TKO trans, lots of suspension stuff, 13" Vette brakes, 18" wheels. Location:Luton
Could it be something as silly as a loose accessory belt ? Just a thought as it's rev related..
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Joined:Tue Feb 23, 2010 12:40 pm Posts:3245 Car Details:'79 Camaro, 350 V8 Location:South Bucks
Quote:
Could it be something as silly as a loose accessory belt ? Just a thought as it's rev related..
Not thought of that! I'll check it - it had about 1/4 inch deflection when installed but the belt wasn't new and haven't checked since it was installed. Probably should put a new belt on it and the power steering. Thanks for the idea!
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