Problem with the alternator...
08-16-2009, 03:12 AM
#1
Burning Brakes
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Problem with the alternator...
Okay, I typed this all out, and it's a wall-o-text, so I'll summarize here and leave the long message below for those who want to know more.
Symptoms:
Oil pressure gauge pegged high, though new and wired properly, didn't peg high before swap of voltage regulator (although I did change the oil thermostat, regulator)
Alternator charges very well at idle, above ~2k RPM voltage output appears sinusoidal, fluctuating between ~11 and 14V, dash lights dimming and brightening accordingly
After running engine at >2k RPM for 30 seconds, I could smell what seemed to be electrical smoke.
Turned off the car, switched it to the "on" position but didn't try to start, and the oil pressure gauge reads 1 bar with the engine off, just as it did before I did any work.
What is going on?
Begin wall of text:
Just spent the day catching up on some odd jobs that needed doing. I did an R&R on the driver's side oil check valve in the cylinder head, replaced the oil thermostat, put in a new lower radiator hose and new spark plugs, and while I had the fan shroud out, I decided to fiddle with my alternator. I bought a replacement voltage regulator, since I have been having trouble with the alternator not charging even while driving at high RPMs. The swap was straightforward, unscrew the two screws, pull the old one out, drop the new one in. I buttoned the car back up and it fired right up (never caught that fast before), and I look at the voltage gauge in the dash and it's reading ~13, just like it normally does for me when I have no accessories running, etc... I then turn on the headlights and to my sheer amazement, the needle barely deflects south of 13, where before the change was quite pronounced. The window motors don't even move the voltage needle, and they move faster than ever before (or it seems so, maybe I'm just excited). At any rate, I see a little bit of smoke and cut the engine off out of reflex to investigate, though it's almost certianly a little bit of oil from when I pulled the valve cover, so no big deal. I go to turn on the car again, and as I turn the key to the on position, the oil pressure needle pegs high, just like it would if the wires were crossed or the sender was defective. The sender was brand new 5k miles ago, and I checked the wiring to find it correct. I then checked the oil, and found I had plenty, so I cranked it up again. This time, I turned on more accessories, and the voltage needle dropped a bit more, so I revved up the engine to see if the alternator would charge the battery at higher RPMs. Sadly for me, the needle started to bounce wildly between 14V and 11V, and the dash lights got brighter and dimmer in sync with the bounce. I got a little worried, but decided to slowly bring the engine up to speed rather than stomping the foot to the floor. Again, I got past 2k rpms or so and the needle started going bonkers on me. I get out of the car and walk to the front, where I smell what seems like electrical parts frying. I shut down the car, and then turn the key to the on position but don't crank. The oil pressure gauge now reads 1 bar, just where it normally does when the engine isn't running. So, what the eff is going on? Did I get an inferior regulator that just blew out? Is that how a new regulator behaves until the contacts break in? I've never rebuilt any alternators, but since the regulator was a separate model on mine, I figured it wouldn't be that bad. Any advice would be greatly appreciated. I've still got the old regulator I can swap back in, and I know that one was working, at least well enough to run the car.
Symptoms:
Oil pressure gauge pegged high, though new and wired properly, didn't peg high before swap of voltage regulator (although I did change the oil thermostat, regulator)
Alternator charges very well at idle, above ~2k RPM voltage output appears sinusoidal, fluctuating between ~11 and 14V, dash lights dimming and brightening accordingly
After running engine at >2k RPM for 30 seconds, I could smell what seemed to be electrical smoke.
Turned off the car, switched it to the "on" position but didn't try to start, and the oil pressure gauge reads 1 bar with the engine off, just as it did before I did any work.
What is going on?
Begin wall of text:
Just spent the day catching up on some odd jobs that needed doing. I did an R&R on the driver's side oil check valve in the cylinder head, replaced the oil thermostat, put in a new lower radiator hose and new spark plugs, and while I had the fan shroud out, I decided to fiddle with my alternator. I bought a replacement voltage regulator, since I have been having trouble with the alternator not charging even while driving at high RPMs. The swap was straightforward, unscrew the two screws, pull the old one out, drop the new one in. I buttoned the car back up and it fired right up (never caught that fast before), and I look at the voltage gauge in the dash and it's reading ~13, just like it normally does for me when I have no accessories running, etc... I then turn on the headlights and to my sheer amazement, the needle barely deflects south of 13, where before the change was quite pronounced. The window motors don't even move the voltage needle, and they move faster than ever before (or it seems so, maybe I'm just excited). At any rate, I see a little bit of smoke and cut the engine off out of reflex to investigate, though it's almost certianly a little bit of oil from when I pulled the valve cover, so no big deal. I go to turn on the car again, and as I turn the key to the on position, the oil pressure needle pegs high, just like it would if the wires were crossed or the sender was defective. The sender was brand new 5k miles ago, and I checked the wiring to find it correct. I then checked the oil, and found I had plenty, so I cranked it up again. This time, I turned on more accessories, and the voltage needle dropped a bit more, so I revved up the engine to see if the alternator would charge the battery at higher RPMs. Sadly for me, the needle started to bounce wildly between 14V and 11V, and the dash lights got brighter and dimmer in sync with the bounce. I got a little worried, but decided to slowly bring the engine up to speed rather than stomping the foot to the floor. Again, I got past 2k rpms or so and the needle started going bonkers on me. I get out of the car and walk to the front, where I smell what seems like electrical parts frying. I shut down the car, and then turn the key to the on position but don't crank. The oil pressure gauge now reads 1 bar, just where it normally does when the engine isn't running. So, what the eff is going on? Did I get an inferior regulator that just blew out? Is that how a new regulator behaves until the contacts break in? I've never rebuilt any alternators, but since the regulator was a separate model on mine, I figured it wouldn't be that bad. Any advice would be greatly appreciated. I've still got the old regulator I can swap back in, and I know that one was working, at least well enough to run the car.
08-16-2009, 03:29 AM
#2
Team Owner
Thomas what is the brand of regulator you installed ? .
First thing i would do is disconnect the battery, then pull out the alternator,there is a good chance that you have gotten a wire misrouted, or you have somehow fouled up the install of the regulator. or the new regulator isnt seated
What was wrong with the old regulator?
Are the brushes worn down?
There is also a possibility that the belts is rubbing on something or its not tight.
What were the symtoms of the charging system B4 you did any work?
Did you verify these results with a muti meter?
First thing i would do is disconnect the battery, then pull out the alternator,there is a good chance that you have gotten a wire misrouted, or you have somehow fouled up the install of the regulator. or the new regulator isnt seated
What was wrong with the old regulator?
Are the brushes worn down?
There is also a possibility that the belts is rubbing on something or its not tight.
What were the symtoms of the charging system B4 you did any work?
Did you verify these results with a muti meter?
08-16-2009, 03:40 AM
#3
Burning Brakes
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mmm, IDK about the regulator brand
pretty sure I haven't screwed up the wiring, as they look like they are in the right places, and they are certianly where they were before I did any work
old regulator brushes were worn down to half of what the new regulator has
belt is definitely tight
alternator would charge on start-up, but not charge when running several accessories at once. voltage needle would deflect when any button/switch was pressed, windows/sunroof could be slow at times.
I did not verify the dash reading with the multimeter, but even if the absolute reading on the dash gauge is off, I am worried about constant voltage spikes, which is what the dash gauge would indicate, so I didn't bother using the multimeter.
Beyond that I don't know anything about regulators. It is possible that it isn't seated, although I doubt that too since there is only one way the unit can go in, and it clearly is supposed to push against a tab on the inside of the alt. Discernable spring pressure would make me think that, if this is what "seating" is, that it is seated fully. Plus the screws went in straight and all the way.
pretty sure I haven't screwed up the wiring, as they look like they are in the right places, and they are certianly where they were before I did any work
old regulator brushes were worn down to half of what the new regulator has
belt is definitely tight
alternator would charge on start-up, but not charge when running several accessories at once. voltage needle would deflect when any button/switch was pressed, windows/sunroof could be slow at times.
I did not verify the dash reading with the multimeter, but even if the absolute reading on the dash gauge is off, I am worried about constant voltage spikes, which is what the dash gauge would indicate, so I didn't bother using the multimeter.
Beyond that I don't know anything about regulators. It is possible that it isn't seated, although I doubt that too since there is only one way the unit can go in, and it clearly is supposed to push against a tab on the inside of the alt. Discernable spring pressure would make me think that, if this is what "seating" is, that it is seated fully. Plus the screws went in straight and all the way.
08-16-2009, 04:07 AM
#4
Team Owner
OK first disconnect the battery.
Then remove the alternator, and inspect the new regulator smell it see if this is where the burning is coming from.
If you have a Bosch alternator it would be wise spend the cash for a new Bosch regulator the aftermarket reproductions are usually pretty cheap .
Inspect the brushes, do the old ones look worn ? are they evenly worn? are they burned?
Look at the slip rings see if its possible that the new regulator was shorting out the slip rings.
Smell everything to find out where the smoke was coming from, ( if you find it(smoke) then please report your findings B4 doing anything else)
Install the old regulator and check the routing of the wire harness to the alternator, install the alternator and with a muti meter check the voltage at the hot post and the battery with engine running, please report your findings
Then remove the alternator, and inspect the new regulator smell it see if this is where the burning is coming from.
If you have a Bosch alternator it would be wise spend the cash for a new Bosch regulator the aftermarket reproductions are usually pretty cheap .
Inspect the brushes, do the old ones look worn ? are they evenly worn? are they burned?
Look at the slip rings see if its possible that the new regulator was shorting out the slip rings.
Smell everything to find out where the smoke was coming from, ( if you find it(smoke) then please report your findings B4 doing anything else)
Install the old regulator and check the routing of the wire harness to the alternator, install the alternator and with a muti meter check the voltage at the hot post and the battery with engine running, please report your findings
08-16-2009, 04:21 AM
#5
Burning Brakes
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Will do. 3AM is a little late to be firing up the car though, so I'll do it in the morning. Thanks for the advice, I'll check it out and report back. Night!
08-16-2009, 01:49 PM
#6
Burning Brakes
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Okay, an update:
I checked over the alternator and I couldn't locate any smell of burning electronics, etc. I don't really know much about alternators, but it didn't look like the slip rings would be a problem. So, I hooked it all up, fired up the engine and checked again. Above 3k RPM (it may have been 3k last night too, don't quote me on my initial 2k claim), the needle bounces. I whipped out the fluke meter, and measured the voltage at the hot post by the B+ terminal and the upper radiator hose, compared to ground on the cross-brace. When the engine was idling, I got about 14.3 V, and when the engine was brought up to where the needle would bounce, I saw a smooth transition up to 14.7V with no discernable bounce or fluctuation. I then turned on the headlights and revved the engine while watching the bulb, and the lights did in fact get brighter and dimmer, just as the dash lights do. However, as I said, the hot post would indicate a smooth and constant voltage supply. Is this a problem in the dash or fuse panel somewhere?
-Thomas
I checked over the alternator and I couldn't locate any smell of burning electronics, etc. I don't really know much about alternators, but it didn't look like the slip rings would be a problem. So, I hooked it all up, fired up the engine and checked again. Above 3k RPM (it may have been 3k last night too, don't quote me on my initial 2k claim), the needle bounces. I whipped out the fluke meter, and measured the voltage at the hot post by the B+ terminal and the upper radiator hose, compared to ground on the cross-brace. When the engine was idling, I got about 14.3 V, and when the engine was brought up to where the needle would bounce, I saw a smooth transition up to 14.7V with no discernable bounce or fluctuation. I then turned on the headlights and revved the engine while watching the bulb, and the lights did in fact get brighter and dimmer, just as the dash lights do. However, as I said, the hot post would indicate a smooth and constant voltage supply. Is this a problem in the dash or fuse panel somewhere?
-Thomas
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08-16-2009, 02:31 PM
#8
Burning Brakes
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Well, the nominal battery voltage is 14.4V, so 14.7 is a little high, but I think it isn't until 15V that you start running into problems. I think the thing that I am more concerned about is the fluctuation in the voltage. I am worried that that might damage electrical components in the car (like the insanely expensive LH brain).
08-16-2009, 03:06 PM
#9
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There really isn't much chance that anything in the electrical system could increase the voltage over battery/alternator voltage, so the variation is probably down from that.
You might start by pulling fuses one at a time to see if you can find what is causing the fluctuations.
It never hurts to clean grounds and connections...
You might start by pulling fuses one at a time to see if you can find what is causing the fluctuations.
It never hurts to clean grounds and connections...
08-16-2009, 03:52 PM
#10
Burning Brakes
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Oh I agree Wally. Am I likely to damage anything by running the car with these fluctuations? I'll certainly have to rev it up a few times while I try to isolate the circuit. I pulled out the regulator again to inspect just in case I missed something. It looks basically like when it went in and doesn't smell funky like it was burned. The brushes are significantly longer than the old unit's, but the size and shape are otherwise identical. The replacement regulator was made by Kahler in Germany, so I suspect that it's probably an okay regulator. I went out to try to find a replacement and found a Well's unit, but it wouldn't fit on the alternator, so obviously it won't work. I'll go put the new regulator back on and try disconnecting things to see if I can find what is causing the problem. Will report back.
08-16-2009, 04:22 PM
#11
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Pulled every fuse (except for fuel pump). The bounce didn't go away upon removal of any of them, though when I pulled the dash pod fuse, obviously the gauge didnt work, but when I plugged it back in, I tested it again and it seemed like it may have taken a second for the bounce to kick in. I could just be imagining things, but in any case, none of the other systems appear to be causing the problem. Any advice?
08-16-2009, 05:04 PM
#12
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+1 on Wally's advice.
Just cleaned my fuses (Haven't got to the relays yet)...huge difference and my alternator readings on the dash have stabilized.
Just cleaned my fuses (Haven't got to the relays yet)...huge difference and my alternator readings on the dash have stabilized.
08-16-2009, 05:57 PM
#13
Team Owner
the voltage readings your reporting seem hi
What kind of alternator do you have and the brand of regulator?
Like i said the cheaper regulators should not be used on your car, if you have Bosch then replace with Bosch parts.
The nominal battery voltage should be about 12.4 measured at the battery.
Its possible that the burning smell was coming from the belt slipping due to the alternator trying to recharge a low battery, and recover from a starting cycle. This is the heaviest load.
You should be seeing from 13.6 to about 14.2 when its charging, if you have over 14.6 than the regulator may be bad
What kind of alternator do you have and the brand of regulator?
Like i said the cheaper regulators should not be used on your car, if you have Bosch then replace with Bosch parts.
The nominal battery voltage should be about 12.4 measured at the battery.
Its possible that the burning smell was coming from the belt slipping due to the alternator trying to recharge a low battery, and recover from a starting cycle. This is the heaviest load.
You should be seeing from 13.6 to about 14.2 when its charging, if you have over 14.6 than the regulator may be bad
08-16-2009, 06:38 PM
#14
Burning Brakes
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I don't see a name printed or stamped on the alternator, but it looks like the bosch one that the car is supposed to come with. I pulled the regulator off and cleaned the rotor that the brushes on the regulator mate with. I also noticed that the brushes were not curved to fit the rotor, so I carefully smoothed them down on a 19mm socket to help them seat better. Unfortunately, this did not help the problem at all. I will drop the alternator and put the old regulator back on and see if this problem persists. At this point I'm thinking I got a bad regulator. The voltage will climb to 15V at 4k RPM which is definitely not correct. The regulator is manufactured by a company called Kaehler, and is made in Germany, which is why I was thinking that it would be okay. It certainly looks nearly identical to the regulator that came out, the only difference being what appears to be a resistor wired between two of the connection points on the inside of the regulator. Perhaps my unit lacks this and that is why it is defective. I will replace with the old and report the results.
08-16-2009, 07:17 PM
#15
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The nominal battery voltage is about 12.6v (not 14.4v - where do you get this from).
Alternators that put out well over 14v are designed for american cars that have deliberately crappy wiring to the battery to ensure it acts as a current & voltage limiter - don't run this way on your Porsche - you will eventually fry the battery charging it that hard.
TO BE CLEAR - there is only one thing that can cause you to have too high a system voltage - the alternator (really the regulator in the alternator). Take it out and have it tested - there IS a problem with it...
Alan
Alternators that put out well over 14v are designed for american cars that have deliberately crappy wiring to the battery to ensure it acts as a current & voltage limiter - don't run this way on your Porsche - you will eventually fry the battery charging it that hard.
TO BE CLEAR - there is only one thing that can cause you to have too high a system voltage - the alternator (really the regulator in the alternator). Take it out and have it tested - there IS a problem with it...
Alan