Should I proactively replace my stock alternator at 200K miles?

CBR.worm

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'06 Infiniti G35 w/ 200K miles. I am resealing the timing cover and replacing the water pump and associated parts for the first time, due to a small oil leak at the bottom edge - it's not dripping yet, but it is getting the front of the motor grimy and I'm sure it will get worse. While I have the alternator off, should I replace it with a new OEM one?

While the alternator is off the car, it would be very easy to replace. This car isn't worth much, but it is fun and in good shape. I plan to drive it until something catastrophic happens, or until it becomes unreliable. I'm replacing the idler pulleys, the radiator, and other pieces that I had to remove to get the timing cover off, also the primary timing chain, chain guides, crank sprocket, tensioner, and gallery gaskets. I read so many horror stories on the internet about the VQ35 tensioner and guide issues and gallery gaskets, but I have no visible wear on anything other than the crank sprocket. No signs of impending doom. I've got the new OEM parts, so I'm going to put them on.

I expect to do a couple of cross-country trips this summer, and while I don't want the car to ever leave me stranded, it would be worse if I was thousands of miles from home. I don't expect the OEM alternator to fail in the next 10 or 20K miles, but it might and I would prefer to not have to touch the serp. belt-driven components again for a long time.

I don't know what the lifespan on these is. It is a Mitsubishi branded alternator. I would think that I have probably used up most of its life, but I really don't know. The mechanical parts on this car seem to last forever.
 

Astro14

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Take your alternator to a good rebuild shop and have new brushes and bearings installed. At least you will know what you have.
This.

If you get an alternator that is rebuilt, you're trading in your good alternator for one of unknown quality that may not last nearly as long. Your OEM alternator is far better than any rebuilt junk from an auto parts store.

Get a shop to do the brushes, and perhaps the rectifier/VR and bushings.
 
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Normally I would say no just leave it until it fails but this one is a bit of PITA to do in a parking lot and then trying to find one on the spare of the moment. 200k in my experience is a good run for an alternator, taking one on a cross country trip would be like buying a plane ticket for next year for a 94 year old.
There is no new OE, they are a reman albeit a higher quality one not some Cardone autozone crap and about $315, not bad if don't have a local rebuilder.




This^^^

I haven't had many Alternator's fail on me, Did have a Denso fail on my 2010 Corolla around 100,000.

Late Nissans aren't known for easy Alternator access!
 
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When my old Rav4 had 300k miles, I proactively replaced the thermostat and radiator hoses, and cap. Also had to replace the radiator because the plastic nipples deteriorated and cracked when I removed the old hoses. I had to remove the alternator to remove the thermostat housing. I put the old alternator back on. In hindsight, I shouldn't have done anything proactively. Old age is hitting me and I'm thinking your 18 year old part is better quality than a new one.
 
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'06 Infiniti G35 w/ 200K miles. I am resealing the timing cover and replacing the water pump and associated parts for the first time, due to a small oil leak at the bottom edge - it's not dripping yet, but it is getting the front of the motor grimy and I'm sure it will get worse. While I have the alternator off, should I replace it with a new OEM one?

While the alternator is off the car, it would be very easy to replace. This car isn't worth much, but it is fun and in good shape. I plan to drive it until something catastrophic happens, or until it becomes unreliable. I'm replacing the idler pulleys, the radiator, and other pieces that I had to remove to get the timing cover off, also the primary timing chain, chain guides, crank sprocket, tensioner, and gallery gaskets. I read so many horror stories on the internet about the VQ35 tensioner and guide issues and gallery gaskets, but I have no visible wear on anything other than the crank sprocket. No signs of impending doom. I've got the new OEM parts, so I'm going to put them on.

I expect to do a couple of cross-country trips this summer, and while I don't want the car to ever leave me stranded, it would be worse if I was thousands of miles from home. I don't expect the OEM alternator to fail in the next 10 or 20K miles, but it might and I would prefer to not have to touch the serp. belt-driven components again for a long time.

I don't know what the lifespan on these is. It is a Mitsubishi branded alternator. I would think that I have probably used up most of its life, but I really don't know. The mechanical parts on this car seem to last forever.
Given how much work you're doing to it now, some needed and some preventive, I would think peace of mind would be paramount in addition to the fun it provides you. Since you're there, yes, do it. OEM. And enjoy your cross-country trips!
 
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I view an alternator like a wear item, not a maintenance item. I replace it if/when it goes out.

Story of a friend of mine who replaced his stock alternator and fuel pump (plus a couple other things) at 150k miles to "ensure no future problems." The replacement alternator went out and left him on the side of the highway after just 15k miles. Just 10k miles later, his replacement fuel pump did the same.

If it's not broken, don't fix it!
 
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I change belt and tensioner every 100k. The Alternator gets a change at the first note of noticable decline. Change the water pump at 300k. I did this regiment on my Civic and it served me well. CVT fluid changed every 10-20k miles and brake fluid exchange Everytime I do plugs and valve adjustment.
 
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My alternator bearings gave out at 250k in my TDi.
No warning, no noise, no shake, wobble or hint of disorder. Just an FYI.
High desert in NE New Mexico. Made some new friends, Great place America.
 

Kestas

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I have been stranded during an out of state travel by an alternator that went out. I think it's a good idea to be concerned how long your alternator will last. I rebuilt the one in my '01 Sable because they are known to last only 100K at times. When I rebuilt it, the old copper contacts were at least half worn.
 
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The 3.5L VQ engine has been excellent for me also. If you buy true OEM from a dealer, it would have to be about $500. I would not buy any remanufactured alternator, and if the box says A-1 or Cardone anywhere, I'd run away.
 
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I always replace with lifetime rebuilds, have good luck with these. ;)
Pretty much all rebuilt alternators have a lifetime warranty. And on average, mine go out anywhere from 70-100k. But I do a lot of city driving/high traffic too where you might average 15-20 mph on a tank of gas so it's doing about 2-3x running hours as opposed to a car that runs on the highway all the time. Which is why I'd say even with highway miles, it's probably on the way out. I always got aftermarket alternators and never had one go bad out of the box although there are many stories of bad ones out there. As others said, probably the best is a shop that rebuilds them for you, but there aren't any shops like that around me.
 
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