Replace/Rebuild a working alternator with 100K?
 

I removed the alternator from my 77 2.7 in the process of doing some other work, and now I'm wondering if it makes sense to do a little preventative maintenance and either rebuild it or replace it while it's out. The alternator is the original unit and has a little over 100K on it. From what I've read, I shouldn't expect it to last too much longer. I'm not sure how this might factor in, but I also plan to go with an Electronic Ignition setup (Clewett/Electromotive) sometime soon (higher output needed?).

Reading some of the posts here, some recommend rebuilding my existing unit, while others say simply buy a rebuilt from Pelican. The best quality choice seems to be the new Australian built units, but $640 is a bit steep.

It also appears from Pelican that the direct replacement for my 77 with the external regulator is NLA, and that I would have to "upgrade" to the Paris Rhone unit which has the built-in regulator (and the extra parts needed to make this work). Is this a good idea, or am I better off simply getting my existing unit rebuilt and sticking with the external regulator? Should I replace the regulator as well if so?

thanks,
Frank

Take it to a local shop and have it rebuilt. I had mine out several years ago and took it back to the shop that rebuilt it 9 years before. They checked it out and said it should be good to go a lot longer and no charge. Also had them refresh my starter during my engine rebuild.

some say the internal regulators usually fails due to engine heat and contributing high heat issues.

100k miles is a lot of miles.

#8 is a noise suppressor that may cause regulator problems. Most times it can just be pulled out of the circuit without issues.


http://forums.pelicanparts.com/uploa...1226242613.jpg

Thanks for the responses. And Ronin, thanks for the diagram. I wasn't sure if the internal regulator was considered an improvement over the external design - at least for where these things live in a 911 environment.

I'll probably go the route of simply having mine rebuilt.

So, from what I've gleaned during my searches, what I should ask the shop to replace are the Slip Rings and Bearings, right? Anything else? Are the slip ring brushes/contacts typically replaced along with the ring?

Now I need to find a shop here in Austin.

thanks,
Frank

I would go to a truck starter and alternator rebulder.

at 100k miles I'd replace diodes with good ones built for high heat.



ps: marine rebuilders are good around here because marine alternators are designed to consistantly run at amps that would cook a car alternator.

Go for the rebuild but I will disagree and say that 100K is not that bad on an alternator. On my daily driver I am running well over 140K on the original alternator. Now it might bite the dust but it has gone 40% longer than you guys say is lots of miles. Then again my daily driver revs up to a maximum of 2500RPM on a daily basis and rarely sees redline of 5250RPM. On a Porsche engine you could be holding 3,000-4,000RPM going down the highway quite easily. This might cause more wear as that is about 50% more RPM than my alternator runs at. Counter to that argument is that my modern car with tons of electronics and stereo is really running that alternator down! OH BOY LOTS TO CONSIDER! GET IT REBUILT!

Like said above, take it to a local shop (look in your Yellow Pages under Alternators), get it rebuilt, should be maybe $100 and you'll be good for another few decades.

Well if it were the Space shuttle with a TBO then maybe,...But they are EZ to R and R so I would wait till the day

ssssoooo much easier to do when the motor is out... a little PM could save a lot of under the hood work later...

The alternator is easier to R&R with the motor out? I find it irrelevant whether the engine is in the car or on the floor to deal with the alternator.

Ok Formerly Steve Wilkinson... the alternator is alreay out... Thats what I was getting at...

An engine stand or leaning into an engine bay ... the same level of difficulty ? maybe .. whats your point? IMO... OK STEVE... IMO it is easier to do with the freakin alternator already removed from the freakin motor...

What is up with some peeps on this board always looking to pick someones post apart....

Well, this is another reason I am considering this job now as the motor is out (I should have mentioned that). I've never tried to R&R the alternator with the motor in, so to Stephan's point I don't know if it would make much of a difference, but it sure seemed more convenient this way. It appears the working room would be a bit cramped with the motor in, as I found removing those 6 air duct nuts was tedious enough as it was. Also, once the air duct was off, I was able to feed some of the wiring harness through the engine shroud and lay the fan housing flat to get a good view of the wiring locations for re-assembly (see picture). Not sure I'd be able to do that with the motor in. I'll post a better picture later from directly overhead if folks are interested in the terminal connections for reference.

Either way, I see a $100 as cheap insurance from having to go in and do this again any time soon.

Frank

http://forums.pelicanparts.com/uploa...1226261256.jpg

Get a grip, Tony, I'm not simply trying to "pick you're post apart." I'm simply pointing out that you may be giving somebody who doesn't know better bad advice when you say "ssssoooo much easier to do when the engine is out." that's a vast--or maybe I should say vvvvaaaaast--exaggeration. Nobody should think twice about removing and replacing their alternator by simply leaning into the engine bay. I've done it half a dozen times.

There are a few things I like to do when I pull a motor and have it on an engine stand.. check the clutch, PP, TO ... adjust the valves and R+R the alternator .... if its history is unknown to me... I like to blow air through the cam oiler tube to make sure none of the holes are clogged..
YES these things can be done with the motor in the car ... but why not do them while the motor is on the stand when I am usually waiting for parts anyway...

Perhaps I did ooovereact a bit and maybe I did put one or two many o's on my so...

But my wife just read your post
and now she thinks she can go rip the alternator out of my 79 and take it over to the shop.

I think what Formerly was getting at was, "don't pull the motor to get at the alternator."

That said, doing anything to the motor is easier when it's out and on a stand, but no one would pull a motor for the alternator alone.

I "think "If you post here you want everyone's opinion ? so that's what ya get.

Tony, don't feel bad, I still get teased because I once posted that replacing a 911 windshield was so easy my wife could do it.

I still see threads about windshield replacement in which somebody is sure to post, "take it to Wilkinson's wife, she'll do it."

My G.F. Always does it. LOL

Boy, this thread sure has become interesting :). I sure didn't intend to stir up any ill will among fellow members. I do appreciate reading various points of view (if constructive) because I sometimes learn that there may be more than one way to achieve the same result.

Perhaps a bit more information here will help. I did not mention this initially because I didn't feel it was relevant to the question at hand, but things seem to have wandered a bit...

So the motor is out (on a jack, not a stand) for some various other (mostly non-motor) work I am doing. And the alternator is out because I am sending the fan and fan housing off to be Nickel plated. So, the main question was since the alternator was sitting in my hand already, should I have it rebuilt given its age and mileage as there will be no extra labor in doing this now other than the trip to/from the shop (it sounds like the consensus is yes). My apologies for any confusion/tension I may have caused.

Regarding the picture I mentioned earlier of a better view of the alternator wiring connections, here you go...


http://forums.pelicanparts.com/uploa...1226276043.jpg

Frank

Here's the bottom line, IMHO: If you want to minimize the chances of getting stranded with a bad alternator, dead battery, etc., then have it rebuilt now. There's no magic to these alternators, and any competent foreign car alternator rebuilder can handle it.

My $.02.

No ill will here... If it was me in the same situation , I would have it R+Rrd while it is out for the $75 it is cheap insurance.... and you wouldnt want to take it back out after you just get everything back in and running...
I would like to see some pics of the Nickel plating on the fan and housing when its done..
vvvveerrrryyy sorry if I mislead anyone with my earlier post... I too have taken my share of alternators out while in the engine bay and still perfer to do it the PM way.. I work in engineering shop at the biggest Hospital in the area and 90% of what we do is PM... I have seen the mess a blower can make inside a RTU when the bearings fail.. its much easier to do it before it fails... plus they always seem to fail at 1 am in January at 20 degrees below zero..
or in the case of an alternator on your way to the Porsche Rally you have been looking forward to going to for three months.
Peace... didnt mean to get this thread sidtracked... I can be really good at maiking a jacka**
out of myself sometime...

Tony,

I will certainly post some pictures of the fan & housing when I get them back from the plater. I have read of folks having this done, but haven't seen any pictures yet (at least in the search I did some time ago).

cheers,
Frank

What could B the emrgency ??? With a dead Alt you still have several hrs of lfe left in your batt in the day time and a couple in the night ....
I run a PC 680... I bet I can get at least an hour out with the lts on !! (@32deg)

Frank, I hope you will have noticed that whatever "tension" you caused was quickly dissipated by a couple of posters having fun with each other. Be cool.

I wanted to post an update after getting the alternator back from its rebuild. The cost was only $85 and it looks so good it's hard to believe it's the same alternator, but the serial number matches, so they did rebuild mine and didn't simply swap it out for another.

Tony,

I'm not sure if you saw my post on this, but you had asked to see a picture of the Nickel plated fan & housing. Check out the following link:

http://forums.pelicanparts.com/porsche-911-technical-forum/445957-nickel-plated-fan-housing.html

http://forums.pelicanparts.com/uploa...1230695659.jpg

http://forums.pelicanparts.com/uploa...1230695699.jpg