Nut on alternator shaft backing off?
07-09-2018, 09:25 AM
#1
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Thread Starter
Nut on alternator shaft backing off?
I can't quite seem to catch a break here...
I replaced the alternator, pulleys, and all belts back in March and have since put 2,600 miles on the car. As per a previous post, while driving last week the ABS and Alternator warning lights came on, and my first step in diagnosing the issue was to tighten the alternator belt which had stretched.
I removed the nut on the alternator shaft and slid off the beveled washer (correct term?) and the two shims outside of the alternator pulley. All the parts appear to be in good condition. I then removed the outer pulley half and one of the two shims between the sections. I then reinstalled the pulley half, placed all three shims outside the pulley, added the beveled washer and re-installed and torqued the nut. I checked the tension with a kriket tool (which I do not have great experience using) and everything looked good. I ran the engine for a few moments and observed several things. The first is the ABS and Alternator lights were still on, and the nut had almost backed off the alternator shaft!
Note: An article on Pelican Parts notes there should be 5 shims and I only have 4. Could this be the problem, or part of it? If so, why was it OK until now?
I took everything apart and tried again, checking torque on the nut (37 lb-ft if my memory is correct - the nut was tight) and ran the engine again. Same results.
I also have a device which is plugged into the cigarette lighter to measure voltage. I am not sure how accurate it is, but while the car was running the voltage showed 10.7, and with the car off 9.8. Clearly this is too low, but given the bolt backing off and no tension on the belt I'm not sure if the alternator is bad or maybe the battery? (The battery was low from driving for a while after the warning lights came on in order to get the car home.) I did get a warranty on the alternator (a new Porsche part), but having to possibly take it out and re-install another is going to be a pain!
Any thoughts on this? Something doesn't seem right...
I replaced the alternator, pulleys, and all belts back in March and have since put 2,600 miles on the car. As per a previous post, while driving last week the ABS and Alternator warning lights came on, and my first step in diagnosing the issue was to tighten the alternator belt which had stretched.
I removed the nut on the alternator shaft and slid off the beveled washer (correct term?) and the two shims outside of the alternator pulley. All the parts appear to be in good condition. I then removed the outer pulley half and one of the two shims between the sections. I then reinstalled the pulley half, placed all three shims outside the pulley, added the beveled washer and re-installed and torqued the nut. I checked the tension with a kriket tool (which I do not have great experience using) and everything looked good. I ran the engine for a few moments and observed several things. The first is the ABS and Alternator lights were still on, and the nut had almost backed off the alternator shaft!
Note: An article on Pelican Parts notes there should be 5 shims and I only have 4. Could this be the problem, or part of it? If so, why was it OK until now?
I took everything apart and tried again, checking torque on the nut (37 lb-ft if my memory is correct - the nut was tight) and ran the engine again. Same results.
I also have a device which is plugged into the cigarette lighter to measure voltage. I am not sure how accurate it is, but while the car was running the voltage showed 10.7, and with the car off 9.8. Clearly this is too low, but given the bolt backing off and no tension on the belt I'm not sure if the alternator is bad or maybe the battery? (The battery was low from driving for a while after the warning lights came on in order to get the car home.) I did get a warranty on the alternator (a new Porsche part), but having to possibly take it out and re-install another is going to be a pain!
Any thoughts on this? Something doesn't seem right...
Last edited by SpeedyC2; 07-09-2018 at 09:27 AM. Reason: typo
07-09-2018, 10:42 AM
#2
RL Community Team
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- Did your voltage while running go back above 13.5 volts once you tensioned the pulley?
- It is unclear to me if you are using the original or the Porsche Technical Service Bulletin discussed updated pulley as the new pulley doesn't have the facility to store extra shims outside of the pulley halves. The updated pulley is a gold color and the pulley halves are cast vs the original being stamped sheet metal.
- Although I have never needed it, have you considered adding a little removable thread locker to the nut to keep it in place.
07-09-2018, 11:23 AM
#3
Rennlist Member
Clean the alternator shaft and make sure it's free of lube/grease, then add some blue thread locker on the big nut. You want approximately 1/4" deflection to either side of mid-line on the belt if you're unsure of the Kriket. Now go for a drive. You shouldn't see 10-11v if battery and alternator are in proper working order. IIRC, you'll need a Hammer or Durametric tool to turn off ABS light.
07-09-2018, 02:06 PM
#5
FWIW, If the Porsche manual call out is for 5 mm deflection on the belt, then 1/4", .250", is too loose. 5mm, .196"; is closer to 3/16", .187"
Shouldn't the nut thds be counter-rotational (tighten) to that of the engine?
Shouldn't the nut thds be counter-rotational (tighten) to that of the engine?
07-09-2018, 02:12 PM
#6
Rennlist Member
Thread Starter
- Did your voltage while running go back above 13.5 volts once you tensioned the pulley?
- It is unclear to me if you are using the original or the Porsche Technical Service Bulletin discussed updated pulley as the new pulley doesn't have the facility to store extra shims outside of the pulley halves. The updated pulley is a gold color and the pulley halves are cast vs the original being stamped sheet metal.
- Although I have never needed it, have you considered adding a little removable thread locker to the nut to keep it in place.
- Voltage did not go back above 13.5, but it seems the nut is backing off quickly
- Original pulley
Last edited by SpeedyC2; 07-09-2018 at 02:12 PM. Reason: typo
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07-09-2018, 04:04 PM
#8
Drifting
Did you rotate then belt/ engine and retorque a few times?
if the belt is getting crushed as you tighten then you won't gat a true tighten/torque and it'll come loose
also I doubt a 10v battery would start the car so that cig lighter voltmeter sounds suspect
if the belt is getting crushed as you tighten then you won't gat a true tighten/torque and it'll come loose
also I doubt a 10v battery would start the car so that cig lighter voltmeter sounds suspect
07-09-2018, 04:12 PM
#9
Seared
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Good point. Unless you grease the insides of the pulleys (don't do this), the belts will not ride up as you tighten the three bolts.
Andreas
07-09-2018, 05:18 PM
#10
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Thread Starter
I had to use a battery starter to start the car, so the voltmeter may be right, but I'm still not sure.
07-09-2018, 07:56 PM
#13
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Ya cannot proceed until you get your battery healthy. Pull it and charge, or replace with new one. Then you can figure out what’s going on with belts/charging system.
07-09-2018, 09:25 PM
#14
Banned
Re: ALTERNATOR BELT PROBLEM ***FIXED***
Note position of Sleeve
Note Pic Order Error: washer / Spacer should be 2nd last. Re-install spacer before the nut
See attached pics
i do believe to tighten add a spacer.
Each car is different.
Different # of Spacers
If using 2 add one.
Then Test
Note
The last bushing as u described it is a Sleeve
Note spacer should be installed before Nut.
Do u see the shiny new Spacer.
The wider part of sleeve is mounted to back of pulley half as per picture.
TJ
Then Test
Note
The last bushing as u described it is a Sleeve
Note spacer should be installed before Nut.
Do u see the shiny new Spacer.
The wider part of sleeve is mounted to back of pulley half as per picture.
TJ
Last edited by TJ993; 07-09-2018 at 09:48 PM. Reason: Pic
07-10-2018, 08:52 AM
#15
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Thread Starter