How long do third gen alternators last? Anyone replace theirs?

I have a 2017 approaching 140k miles. In my experience alternators last about 7-10 years or 150,000 miles. Anyone have to replace theirs within that timeframe?

 

Use it until it dies! I have never preemptively replaced an alternator. Now batteries are a different story.

 

Fix It Until It Is Broke is my motto.

 

For reference, my 4Runner has its alternator go out at 15 years / 162k miles. Life expectancy will depend on contamination. Being caked in dirt and mud will probably kill it sooner. My 4R was a pavement pounder, but had a timing cover oil leak which may have shortened the alternator's life.

At your mileage you can order a spare to keep on hand. Watch for warehouse closeout deals on Rock Auto (which would not carry a core charge). I wouldn't replace a functioning alternator preemptively though.

 

Alternator is one of those things that may go out at <100k or may go over 300k

One thing you can do to keep it alive as long as possible is keep a good battery in it, weak batteries put alot of stress on alternators and starters and can make them fail prematurely.

 

There are many variables involved so it's hard to determine. Most times just luck of the draw. My 2020 going strong. My truck is stock. Adding lots of electrical draw may shorten life among other factors.

 

If your town has a quality electrical shop, I've found it less expensive for them to do a full rebuild, including R&R, than to get a parts house bit and wrestle with it myself. Especially if you score a bad unit and get to do it again under warranty.

Since you're working now, maybe it's time to see if you can find such a shop, have a convo with them and see if you'd feel good about their services.

 

For potential longer alternator life, after an outing with lots of mud/dirt/dust/etc, after you clean the truck, take some electrical parts cleaner and spray into and around the alternator, into the solenoid through the accessible gaps.