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Pelican Technical Article:

Alternator Replacement

Time:

4 hours4 hrs

Tab:

$400

Talent:

**

Tools:

Socket set

Applicable Models:

Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-08)
Porsche 987 Boxster S (2005-08)

Parts Required:

New alternator, new drive belt

Hot Tip:

Tap the inside bushing to release it from the bracket.

Performance Gain:

Consistent charging output

Complementary Modification:

Replace drive belts
101 Performance Projects for Your Porsche Boxster

This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.

One of the nice things about the configuration of the Boxster engine is the relative ease with which you can replace the alternator. The alternator is nestled neatly on the right side of the engine compartment: very easily accessible. The replacement and repair process is straightforward, and should take you about an afternoon to complete.

The first thing that you need to do is to make sure that your alternator is indeed the cause of the problems with your charging system. Sometimes bizarre electrical problems can be caused by a number of faults other than the alternator. It's important to troubleshoot the system prior to replacing your alternator.

The first thing to check is the belt that drives the alternator. Is it tight and amply turning the alternator pulley? If it's worn or close to breaking, then replace it and recheck the alternator (see Pelican Technical Article: Drive Belt Replacement). Modern belts seldom break, but they get brittle and glazed with age, and can slip on their pulleys.

The next item to check is the voltage at the battery. This should read a little more than 12 volts with the engine off. When the car is running, the voltage should read at in the range of 13 to 14.5 volts with the engine at 2000 rpm. If your battery appears to be leaking, then your alternator's voltage regulator has probably failed. The battery will usually only leak acid if it has been overcharged at a much higher voltage. If the voltage measured at the battery is more than 16 or 17 volts when the engine is running, then the regulator is probably bad. If your battery has boiled over and has acid overflowing out the top, make sure that you clean up any spilled acid immediately. Dousing the area with a water and baking soda solution should help considerably to neutralize the acid, and prevent it from eating away at the metal.

An important item to check on your car is the engine ground strap. The engine is electrically isolated from the chassis by rubber motor mounts. If the engine ground strap is missing or disconnected, then you might have a whole bunch of problems, including electrical system malfunctions and difficultly turning over the starter. See Project 81 for the exact location of this ground strap.

Before starting any work, make sure that you disconnect the battery. The positive battery terminal is directly connected to the alternator, and it can be dangerous to work on if it's live (see Pelican Technical Article: Battery Disconnect Switch / Battery Buddy Installation).

The first step is to remove the belt that drives the alternator. Refer to Project 5 for detailed instructions on the belt removal. Removing the alternator from its bracket itself is a relatively straightforward process. Start by loosening the large B+ cable that is located inside the top of the engine compartment. See Project 3 for instructions on how to access the engine compartment.

Now, loosen but do not remove the lower alternator bolt (green arrow, Figure 3). Then, loosen the idler pulley that is located next to the alternator. Loosen the bolt and back it out about 3-4 full turns. Then, using a drift and a hammer, tap on the bolt. The purpose for doing this is to loosen up the metal bushing that is located inside the rear flange of the alternator. With the bushing loose, lift up on the idler pulley, and the alternator assembly should rotate counter-clockwise. Remove the lower bolt, and the alternator should be able to be lifted up and out of the engine.

On this particular car, this bushing was a tight fit and required quite a bit of tapping, and quite a bit of wiggling to remove. Specifically, I had to use a very long drift to tap directly on the rear bushing to get the assembly loose. Other mechanics seem to indicate that this is a common problem, so you might have to work at it a bit to get your alternator out.

With the alternator unbolted, disconnect the electrical connections from the rear. Reminder: don't touch these connections while the battery is still hooked up (Pelican Technical Article: Battery Disconnect Switch / Battery Buddy Installation).

If you are replacing the alternator completely, then the installation of the new alternator is simply the reverse of the removal process. Make sure that you reconnect all of the wires to their proper terminals when you are done. If you're still not sure if your alternator is bad, you can take it to any good auto parts store, and they should be able to test it for you for a modest fee.

Shown here is a brand new rebuilt alternator.
Figure 1

Shown here is a brand new rebuilt alternator. Unlike older-style Porsche alternators, this one is pretty much plug-and-play. The regulator is internal, and the alternator should come with the proper pulley installed on the front. The green arrow in the inset photo shows the metal bushing that may give you trouble when you try to remove the alternator. This bushing is the one that needs to be tapped on in order to loosen the assembly for removal.

With the top of the engine compartment open, loosen and disconnect the cable that attaches to the alternator.
Figure 2

With the top of the engine compartment open, loosen and disconnect the cable that attaches to the alternator. This will allow you to pull the unit out and away from the engine compartment.

You can access the alternator assembly through the engine compartment access panel behind the seats.
Figure 3

You can access the alternator assembly through the engine compartment access panel behind the seats. Simply loosen both mounting bolts. Turn the idler arm bolt back about 3-4 turns.

Using a metal drift or punch, tap on the bolt to push out the rear metal bushing.
Figure 4

Using a metal drift or punch, tap on the bolt to push out the rear metal bushing. This may require some significant tapping. If the bushing is stuck, you may end up damaging the idler pulley bolt. Don't fret though, as a new one is only $5.

With the alternator disconnected from its bracket.
Figure 5

With the alternator disconnected from its bracket. Pull the unit out of the engine bay and disconnect the two electrical connections on the rear (blue and red arrows).

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Comments and Suggestions:
R Comments: What's the part number for the idler pulley as well as the bolt it's mounted on? I'm working on a 1997 Porsche boxster base, 2.5 liter
November 26, 2016
  Followup from the Pelican Staff: http://www.pelicanparts.com/cgi-bin/supertech/catalog.cgi?action=frameset&return-url=/cgi-bin/supertech/catalog.cgi%3Faction%3Dframeback%26page%3D589&catalog-url=http%3A%2F%2Fwww.pelicanparts.com%2Fcatalog%2FSuperCat%2F1041%2FPOR_1041_ELCHRG_pg1.htm %3Futm_source%3DSuperTech%23item0 - Nick at Pelican Parts  
Daniel Comments: When removing the plugs from the rear of the alternator the blue wire came undone from the connector. When reattaching it, should I place it in hole 1 or 2 of the connector? I have a 98 2.5 liter motor. Thanks in advance.
January 8, 2016
  Followup from the Pelican Staff: I recall it being terminal one.- Nick at Pelican Parts  
Rolan Comments: Thank you.. this is a very helpful resource... I soaked all bushes/bolts overnight in wd40 and all came apart ..without any hammering... just rotating / shaking and a little upward pressure with pry bar...I've probably been lucky. I only have the thick wire and the blue wire in the connector..ie no red wire. My car is a Uk 99 986 manual. Do I need to look further.. or is this ok for refit? thank Rolan
August 5, 2015
  Followup from the Pelican Staff: Your vehicle may be different. Not sure as I haven;t worked on a UK model. - Nick at Pelican Parts  
Dave 86 930 fl Comments: Great info regarding replacement of alternator, thanks to all at pelican. I did have a difficult time getting the alternator out of the engine compartment once it was free due to the guard above the pulley being in the way. I attempted to remove the guard, but while I may have been able to remove it, there was no way I was going to be able to reinstall it due the the placement of the bolts. My solution was to remove the long bolt with the pulley on the alternator itself. Once removed, easy peasy something nezzy. I just ordered a rebuilt Bosch unit from Pelican ... I never thought I'd appreciate working on my 930, but I'm having second thoughts. Thanks again to all that contribute to this thread.
August 1, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Lu Comments: By the way for my previous post it was a 97 Porsche boxter
May 2, 2015
  Followup from the Pelican Staff: See other post... - Casey at Pelican Parts  
Lu Comments: Hello, i just ordered a voltage regulator from you guys. My car was running at 11.3 volts at idle and the tester at oreilly said it was a bad volt reg after i put the new one it ran the same at 11.3. Pelican parts Part # was 000-043-206-37-M14, The one on the box said F 00M 144 136 and my original says F 00M 145 200 . I am just wondering if i got the wrong volt reg or my alternator needs replaced?
May 2, 2015
  Followup from the Pelican Staff: Yeah the voltage regulators have been superseded and the new number is correct. Looks like the alternator needs to be replaced. - Casey at Pelican Parts  
BartyB Comments: As others have observed, this bushing is a truly awful design. I gave up using a hammer on the pulley bolt and instead used roughcut softwood wedges about 6" long with a 10° angle placed underneath the alternator and gently tapped in whilst applying a bit of turning force to the alternator around the long fixing bolt. This ensured no damage to either the alternator or block. After around 30 minutes of working the alternator up and down, eventually it came free of the retaining channel. After removing the alternator, I took it to a local engineer who, using a workshop press, pressed back the bushing until it was flush with the inner surface of the alternator. This provided enough of a gap to allow easy re-installation after I replaced the voltage regulator. Just remember to vacuum clean any wood debris from the engine if you use this method. Many thanks for providing such a helpful resource and practical advice, BTW.
November 29, 2014
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Rustyrotor Comments: A bit confused. I see online that the regulator is available, but Porsche folks have repeatedly stated that the regulator is integral with the alternator, meaning that to replace the regulator you must also replace the alternator. The excellent article above doesnt clear this up for me. My issue: CR 220 only operates under high voltage loads, IE defroster and high beams on, or with the engine off. Sometimes when the oil separator fires up the radio will come on. Cuts off under most other circumstances.
November 13, 2014
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
lou Comments: removed alternator from 2005 9964s when i unplugged the connector going to the regulator i found only 1 blue wire instead of two even though the connector is 2 wire is there a reason for this
November 7, 2014
  Followup from the Pelican Staff: One blue wire is normal. - Nick at Pelican Parts  
Brent Comments: Thanks for all info you offer here, it really helps the owner who enjoys working on his car. Just two quick things that helped me. 1. There are two slots for the large cable, it has to go in the correct slot. Impossible to install if in the wrong one. See figure 5. 2. I couldn't get the alternator to slip into the upper bracket/slot. Ended up polishing the front of the top bracket with a Dremel tool. Slipped right in.
October 21, 2014
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Frank Comments: I read and re-read this thread and it's still unclear to me if you need to take the long bolt that holds the pulley in place and appears to go through the Alt. I can't see how you can replace the Alt without taking this bolt and pulley out. Please advise and TIA.
June 2, 2014
  Followup from the Pelican Staff: The bolt that runs through the idle stays in place, when you loosen it, it comes out with the alternator. Loosen the bolt three turns, then tap it toward the alternator with a soft-faced hammer. - Nick at Pelican Parts  
fishski Comments: I read and re-read this thread and it's still unclear to me if you need to take the long bolt that holds the pulley in place and appears to go through the Alt. I can't see how you can replace the Alt without taking this bolt and pulley out. Please advise and TIA.
June 2, 2014
  Followup from the Pelican Staff: The bolt that runs through the idle stays in place, when you loosen it, it comes out with the alternator. Loosen the bolt three turns, then tap it toward the alternator with a soft-faced hammer. - Nick at Pelican Parts  
geoman Comments: I had a clicking noise, i thought was in the belt/pulley system, but when I took the belt off and ran the engine, it must be in the engine or clutch. When i get to around 2000rpm, it quits. really sounds like something hitting against something? Baffleling. 2001 Boxster 2.7L
September 19, 2013
  Followup from the Pelican Staff: Check if the noise goes away when the clutch is pressed. If so it could be the clutch disc or throwout bearing. It's hard to give noise advice without hearing where it is coming from. Can you pinpoint the area? - Nick at Pelican Parts  
geoman Comments: 2001 Boxster, have wining noise from 1 of the pulleys, hard to know which one9maybe a bearing going bad? but I by-passed the a/c compressor 1st, now I have removed the alternator, thinking that bearing was bad, but how do you remove the decoupler pulley?
August 26, 2013
  Followup from the Pelican Staff: Usually with modern cars the alternator would be replaced as a unit. If you want to rebuild it, you'll have to contact a local rebuilder to see if they can source the parts for you. I'm not aware of separate alternator parts for your vehicle. - Nick at Pelican Parts  
Porsche Fan Comments: I can't tell you how much I appreciate the in depth detail of every project you list on here. I guess you can call me a "car guy" for the love of cars i have. But I never got my hands dirty - not even so much as an oil change. I can proudly say that my first project was replacing the alternator on my 2003 Porsche Boxster. The details you provided have my the confidence to proceed with the project. 4.5 hrs later new alternator and new belt were installed. I just took her for a run and she's purring beautifully... Thanks!
May 18, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  
Patrick Comments: I just replaced the alternator on my 2002 Boxster S, this site has been very useful, thank you for doing it. I did come up with a few suggestions. 1. I did hammer on the ider bolt to push back the bushings and like others found it difficult. My solution was to spray the bushing with liquid wrench then hammer on the bolt with an air hammer this made easy work of the bushing just a couple seconds worth then check for looseness though you will need an air compressor and air hammer. 2. The new alternator's bushing was pushed forward which made reinstalling difficult, therefore, I took the alternator to the vise and with the help of a large and small socket and more liquid wrench pushed the bushing back much like pressing a universal joint. 3. When reinstalling the alternator you can stick your hand through the intake manifold and get a couple fingers to hold the alternator as you get into place. 3. Last when removing the alternator you will ask why can't not just remove the idler bearing bolt- becasue there isn't room to remove the bolt and bearing. Plus the bushing holds the alternator in via friction so the bolt isn't the issue.
July 10, 2012
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help. - Nick at Pelican Parts  
TC Comments: Just completed the alternator replacement. One warning that would have been helpful...don't start the engine with the passenger seat removed. I did and now the airbag warning light is illuminated. Any way to clear the fault without a trip to dealer?
March 10, 2012
  Followup from the Pelican Staff: Unfortunately, an airbag fault can only be cleared using a scan tool. - Nick at Pelican Parts  
Mickey Comments: I just replaced the alternator on my Cayman S and there are a few differences from the Boxster article. First, there is absolutely no acces to the alternator from the upper engine access panel - it all has to be done from behind the seats. Second, it's not a simple bolt but a star bolt and you need a particular socket to get both of the alternator bolts off. The longer one butts up against the bulkhead to you really have to finesse the bolt out.
December 25, 2011
  Followup from the Pelican Staff: Thanks for the updated info! - Wayne at Pelican Parts  
Brian Comments: Yeah, just need to hammer away on the bolt with the bushing. I ended up making a video http://youtu.be/jUjJqK8qJDE. Thanks Wayne, your parts and instructions were spot on.
November 11, 2011
Jos V. Comments: I just replace my alternator. The hardest part is to push out that bushing connected to the roller's bolt. I followed Wayne's instruction. After an hour, there is no luck so what I did is I totally removed out the bottom bolt. Spray the bushing with oil and used my breaker bar or any solid steel bar and pried up the alternator against engine block. It worked.
November 10, 2011
  Followup from the Pelican Staff: Thanks for the tip, these can indeed be a bear. I don't know who's the genius who designed this, but it doesn't work very well. - Wayne at Pelican Parts  
Wayne at Pelican Parts Comments: If you have a problem with your alternator, it may be the decoupler pulley, which is a special pulley that is installed on the alternator that allows it to spin up when the engine is accelerating, but free-wheel rotates when the engine is decelerating. This is because the rotating mass of the alternator will work against the belt when the engine is decelerating and can cause premature belt wear. I found this neat video online here from Gates, a well-respected belt manufacturer: http://www.youtube.com/watch?v=hrFcPqZuO3A&feature=related
October 18, 2011
Brian Comments: I am having a devil of a time getting this alternator out. I have hit and hit the bolt with a punch, the bushing doesn't move. I am able to get the bolt almost out of the housing, it hits the firewall and I'm afraid the force it. Any other ideas on how to get this thing out?
October 5, 2011
  Followup from the Pelican Staff: See the comment above here. It's a bear to remove, you just need to keep working at it. - Wayne at Pelican Parts  
Thomas Comments: I have a Cayman, is the process the same?
And does it matter to have a manual or tiptronic alternator? I have a six spped manual
August 4, 2011
  Followup from the Pelican Staff: Yes, the process should be almost exactly the same, with the only exception being how you access the top of the engine of course. - Wayne at Pelican Parts  
Nathan Comments: The bushing on my 2002 Boxster S was rusted solid. I was able to get the alternator out. It would have been easier if this bushing had loosened. I have attached a photo of a bushing that HAS NOT been tapped back out of the way
July 14, 2011
  Followup from the Pelican Staff: Indeed, as you have seen from the comments here, this is a terrible design. Thanks for the informative photo! - Wayne at Pelican Parts  
Jerry Comments: Thank you so much for the article. I found it necessary to punch the back bushing even further than just loose, to maybe 1/18 inch. Then remove the long bolt. This allowed me to slip a small thin steel pry bar between the engine and alternator to balance the alternator while I rotated it clockwise. Both in and out were a breeze with the back alternator bracket fitting easily under the engine mounting bracket both in and out. The key tool that helped me the most the heavy duty paint finish remover tool that helped balance the alternator and minimize finish damage to all parts involved. Secondarily, I worry about future replacement due to the Bosch Bushing design. I did not do a metal analysis and so maybe it will be of no concern. However, rust, corrosion, whatever, does happen and I visualize the bushing spinning once corrosion starts on the bolt threads. Maybe a light thread surface treatment would be helpful for the next alternator replacement.
20-20 hindsight: I’d suggest a protective cloth to cover both the engine front and firewall. The alternator hits the firewall while the electrical connectors are removed and removes the paint on the edge of the firewall. That will rust out at the edge.
Thanks again for the article. It’s first Porsche I’ve worked on and never been beaten by an alternator. But this one came as close as any.
Thanks again for your help
Jerry
June 14, 2011
  Followup from the Pelican Staff: Thanks for the tips. I don't know who designed this alternator setup, but I think they should probably be fired in my opinion. - Wayne at Pelican Parts  
Jim Comments: Where does the metal bushing of the alternator connect to or go when you tap it out. Does the idler pully have to be completely removed?
November 24, 2010
  Followup from the Pelican Staff: It's hard to explain - the bushings doesn't really pop out - it's embedded into the alternator bracket. You're just loosening it up a bit so that you can get the alternator out. It's a bit of a goofy design. - Wayne at Pelican Parts  

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