Intermittent Alternator

[danmartinic]

Hey Folks... nice weekend drive to Capital City.. car dies half way through. The charging meter started dropping.. after about 20 mins fell to about 10 and car died shortly after.

My battery is over 10 years old. Alternator is original.

The tow truck guy performed some test and suggested it's the battery. Bought a new one. On first start up, car ran with over 14 volts at battery. However, while leaving for home yesterday, shortly after getting on the highway, the charging meter falls again.

Towed car home and... now what? Take the alternator out and get it tested? Replacement will take a few days to get after ordering so I need to move quick here (this is my daily driver).

Is there a regulator or some small part that could cause this? Does a bad alternator ever go from full charging to nothing so quick?

Wires & ground around the battery seem fine but of course, I haven't checked alternator side yet.

What would you do?

951... 300,000kms... daily driver

Thanks,
Dan

[danmartinic]

I just found a new voltage regulator for cheap. Looks like the brushes are part of it?

Seems to me if the alternator puts out 14v then suddenly nothing, most likely either a bad wire or this regulator?

I think I'll just try the regulator first. While I'm there, might check on the wires.

Anyone have experience replacing just the regulator? Is this a common thing to go?

Dan

regulatorvr179.PNG (63.52 KiB) Viewed 1776 times

[usury]

I think I'll just try the regulator first. While I'm there, might check on the wires.

Anyone have experience replacing just the regulator? Is this a common thing to go?

Dan

I've done it twice in the last 20 years. Alternator has about 250k miles. Most recent regulator/brushes have maybe 8k.

[danmartinic]

You've changed this regulator twice.. and the alternator itself still the same?

Are these brushes that are on the regulator the only brushes in this alternator? Seems a bit odd the way they are situated in back like that..

[usury]

That's right. I've changed the brush/regulator pack at the back of the alternator twice. It is still the original alternator. The car (and consequently the alternator) has 250k miles. (I've owned it since it had 120k miles, which is usually about 30k miles before the brushes/regulator seem to fall, so I surmise the car has it's original alternator.)

I don't have personal experience with the internal construction of the alternator, but I believe they are legendarily robust.

[danmartinic]

Wow.. I've been driving mine since I bought it in 2008 with 110k (69k US miles).. I have to check my notes, but I can't remember ever changing the alternator belt (?).. probably once with the first timing belt. Definitely never touched the alternator itself!

I hope the legend holds true

[crackership]

I cannot speak highly enough of the Nissan Quest alternator retrofit. It's definitely not as straight-forward as an OEM replacement but I didn't think it was difficult. Fair warning, though, It does require a bit of cutting on the alternator bracket, a touch of grinding on the new alternator mount, and splicing on a new plug but it charges much better, it's a whole lot cheaper than the OE replacements and it's much smaller (makes fitting a big turbo much easier).

Do a google search for "944 nissan quest alternator" and you will find very detailed threads on other forums.

Order this alternator. Make sure to specify you want the Porsche pulley when ordering

Also order this plug pigtail to make wiring it in super easy.

And I recommend a terminal boot, something like this . The power lug for the Nissan alternator is right on top so it's easy to bump it.

[Tom]

So that no one needs to leave the safe and cozy confines of Carpokes, here is my to-the-point summary of installing the Nissan alternator. The other sites have super long threads, which do contain all the info needed, but it's spread out over dozens of pages with lots of old/dead links... Just say'n.

Overview: The basic idea is to replace the stock alternator with the alternator from a Nissan Quest. This is a more traditional looking alternator and, importantly, gives you room for bigger turbos, MAF pipes, etc. In order to make it fit, you need to grind both the alternator case and the alternator mount. When grinding the alternator, either disassemble it so you can grind the case without getting metal shavings inside, or carefully mask off the case so nothing can get in there. And wear goggles, trust me on that.

Alternator: 1998 Nissan Quest sold with 6-rib pulley (in lieu of original pulley that comes with alternator – i.e., don’t expect an alternator from your local parts store to have the right pulley). You need to request this pulley when ordering. While the eBay guy linked below was very helpful and tried to make everything right, I had 2 or 3 of his alternators go bad in very short order, so ended up putting his pulley on a high-end rebuild from a local auto parts place. When I took the case off to grind it, the difference was day and night. The good one had all-new innards, whereas the eBay one looked old inside with a few fresh parts added. Your results may vary.

https://www.ebay.com/itm/273037406072?h ... R8KilLiTYQ


Electrical Jumper for alternator: Part # C1900. I terminated the wires with a standard WeatherPac and eye-ring connectors as shown. (You could also use spade connectors in a pinch.) You can see this in the alternator picture below.

http://store.alternatorparts.com/partnoc1900.aspx


Post Insulator: I found these post insulators at Summit – Ron Francis CC14 post boots. They are an ok fit – way better than not having-- but still on the look-out for something that seals around the alternator post a little better.

http://www.summitracing.com/parts/rfw-cc14

alternator insulator.jpg (146.93 KiB) Viewed 1759 times

Bolts and nuts: I had to use a 140mm M10 bolt on the pivot mount of the alternator, with a mechanical locknut on the back end. After grinding the tabs, there will be a gap between the pivot ears when you install the alternator and slide the 140mm bolt in place. Be sure to install washers/spacers so that the alternator sits in the bracket fairly tight. I used a thick M10 washer as a shim and ground it a bit thinner as needed so that the alternator was factory-tight in the bracket. Otherwise, the alternator might wander forward/backward and prematurely wear the belt or bearings. I used a 65mm M10 bolt on bottom, also with lock nut. McMaster sell any hardware you might need.

In the picture of the alternator below, the blue arrows show the electrical connections. I used WeatherPac connectors to mate the blue wire in the factory/iceshark harness to the blue wire on the alternator. I added a standard eye-ring connector on the red wire, and adhesive lined heat shrink.

alternator connections.jpg (119.23 KiB) Viewed 1759 times

The arrows marked A show where I ground down both surfaces so the pulleys all line up. I had to remove just under 6mm from the pivot mount side and about 2mm from the fixed mount side.

The arrows marked B show where I had to grind away material to clear the factory mounting bracket. The red arrow marked C shows where I had to grind about 8mm off the forward face of that mounting tab, to prevent the bolt from hitting the belt that passes right in front of that tab.

The green arrows point to where I drilled the mounting holes. I used a 13/32” on the pivot side (i.e., the closest I had to 10mm) but had to use 7/16” on the fixed mount side in order to get the bolt to slide through.

Picture of bracket shows where I ground/cut for the alternator to clear. Grinding the mount and alternator case is by far the biggest part of this job. I did it all with a cheap Harbor Freight side grinder.

altanator bracket.jpg (95.74 KiB) Viewed 1759 times

[crackership]

So that no one needs to leave the safe and cozy confines of Carpokes, here is my to-the-point summary of installing the Nissan alternator. The other sites have super long threads, which do contain all the info needed, but it's spread out over dozens of pages with lots of old/dead links... Just say'n.

Way to go the extra mile, Tom!

Do we have a knowledgebase or tutorials section here on Carpokes? It'd be great to have a place to collect detailed diy walkthroughs like this where the threads can be kept concise and can easily be found. I'd be happy to help contribute with some of the mods I have done myself. I'm also always a little worried Sean (Refresh951) will let his domain expire now that he's moved on and there's some great info on his site

[Tom]

YES!! See the Instructions and Technical Files section below.

viewforum.php?f=19#start_here

I've been populating it with all sorts of 951 DIYs I've written and we have a small sampling of how-to's from others. I was actually going to do one on the Nissan alternator, but hadn't gotten around to it yet. But when I saw your post, I didn't want a single Carpokean thinking they had to go elsewhere so summarized it in my post above.

I would absolutely love to see Carpokes become the leading repository of 944/951 how-to's -- I've been working on it -- so by all means I'd love to have you (and others) start contributing. Clarks is an awesome reference, but it's been static since Clarks passing (and my inquiries to link up with them have all gone unanswered), so think there is benefit in building a new and dynamic library. I also value DIY's with a little more detail and real-world tips, which hopefully you can see in the DIY's I've posted to date.