james250

Alternator on IS250 Replace it or wait until it fails?

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My IS250 is just over 190k miles and i've been reading a lot on the american forums of the alternators failing. Seems like people there report it as a common problem with the IS250. I haven't seen as many reports here in UK forums but there have been a few recent incidents on here of failing alternators. It got me thinking, should I replace my alternator as a safe measure or should I wait until mine dies? I tested the alternator with a multimeter, on start-up with lights and AC off it pumps out over 14volts. I also used one of those cheap alternator and Battery testers and the LED reports alternator as good. My alternator could be on its way out or could have lots more life left in it, there's no way of really knowing. What would you all do? The thought of a failing alternator on the middle of a motorway just sounds scary, eventually you'd have no lights and stuff to even have hazards on for people to see you.

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take out brilliant RAC full breakdown etc cover

happened to me last Friday at 227k miles .......... paid for taxi and car recovery to my indy mechanic, collecting the car fixed today

My Honda Legend, a couple of months ago the alternator failed at about 119k miles, but bang outside the house in daylight

RAC recovered the car to my indy likewise, some 50 miles away

You cannot predict alternator failure ( I think ??? ) so just take precautions to protect yourself for when it does just go ' pop '

Malc

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My cars not on 70,000 miles yet let go coming home 1 am. Car started run for 6 minutes to defrost drove 100 foot, no lights on dash board at all. No headlights or sidelights,

no power steering a knight mare. Shorted out fitting new alternator main fuse box . I would not wish this on anyone, fault Vsc and traction control when car got running.

Fixed using the paper clip methord, every thing alright at the moment. I am thinking of doing starter and water pump, as all original as far as i know.

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I forgot to mention, I do have RAC full cover

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That is good i hope it does not fail on a motorway, my bearing was alright no warning at all just packed up.

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The thought of changing a fully functioning part ( I know at the moment!) I think is ridiculous, will you consider changing Starter motor also? As this could leave you stranded ( but with lights still working)

I do read the US owners site and yes they seem to have a lot of Alternator failures but then understand that there are considerable more IS models on the road over there than here and also some of the states concerned are very much hotter than here and heat is the enemy of any electrical component!

paul m

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17 minutes ago, Texas said:

The thought of changing a fully functioning part ( I know at the moment!) I think is ridiculous, will you consider changing Starter motor also? As this could leave you stranded ( but with lights still working)

I do read the US owners site and yes they seem to have a lot of Alternator failures but then understand that there are considerable more IS models on the road over there than here and also some of the states concerned are very much hotter than here and heat is the enemy of any electrical component!

paul m

Thank you Paul, I was thinking the climate might have something to do with it too. I don't like the idea of replacing it either seeing as it's working but the thought of just losing power sounds a bit scary. Other things like if starter was to fail, at least i'm parked already somewhere and can get RAC. Worth changing the drive-belt? i changed it as a preventative measure at about 100k last. How often are drive belts to be changed?

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100k is as good a point as any to change the aux drive belt seeing that there is no actual set time/mileage in the Lexus schedule! It first makes mention to a visual inspection at 72 Mths/60,000 Miles then every 18 Months/15,000 Miles ( obviously replace if deteriorated in any way )but no actual periodical replace point!

paul m.

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Mine was well worn looked ok on visual inspection. No cracks or chunks missing, but had less than a quarter left was not far from the cord. Nice easy fix and was done as a

matter of coarse with new alternator.

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My alternator failed.

Before it did, I had the following symptoms which lasted for approx 500 miles.

After a long enough journey (up to temp), there was a distinct smell of electrical burning coming off the front end once I had parked up on the drive. Then came the whining on a cold start. If you have looked after your IS250 and your engine is silky smooth and quiet like mine usually was (and is once again), then you will know about the whine as soon as it starts to happen. Annoying as hell!

When you get either of these symptoms, get it replaced.

When the Battery light came on, I went straight home. Left it on the drive until it was booked in for a replacement and then drove it once approx 2 miles to the garage with no problems. I guess I had enough juice in the Battery.....

I wouldn't replace it until you get sure signs its on its way out......no point.

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On 1/10/2020 at 9:10 AM, Malc said:

You cannot predict alternator failure ( I think ??? ) so just take precautions to protect yourself for when it does just go ' pop '

Yes you can do protective maintenance like changing brushes and cleaning (usually dust is the main cause of electrical failure) same for motor starter  

However for 190k and 14 years it lasted long anyway.

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my alternator packed up a year ago (2006 model) so 12 years.  If it is on your mind, I would look now for replacement ones and how much they cost, who will install it etc. a good mechanic and/or auto electrician could do this for you. salvage yards maybe a good idea. im really impressed with your mileage. how does the car run? mines hit 122k. no issues! smooth as anything!

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