I think my car's alternator is going out

[thomas-dash]

My car engine started whining recently and it seems to match the same sound as some of the YouTube videos I watched online that said it was the alternator causing the noise. My car has around 150,000 miles on it, so it was probably time to replace it.

I'm thinking about installing a high output alternator that is a drop in replacement for my car. The stock alternator is a 100A alternator. I found one online that says it has an Idle Output of 125+ Amps and a Full output of 250+ Amps @ 1200 Engine RPM. I think the higher output alternator might be a good idea since I have that DC/DC charger in the trunk pulling an extra 20 amps when the LiFePO4 battery is in the bulk charging phase. Even at idle, it seems like it would have more than enough power while the charger is pulling 20 amps.

What do you think?

 

[Nigel]

What sort of vehicle is it?

I think 100A is sufficient for most vehicles, but a 100A alternator isn't necessarily designed to produce 100A continuously, so a bit more maybe a good idea if you are actually using much of the other 80A regularly. 250A sounds like overkill to me, but if it doesn't cost too much more...

The other thing to consider is if you need to upgrade the car wiring to cope with the extra power, it is unlikely that the standard wiring was designed with that much spare capacity, and very unlikely that the fuses were...

 

[thomas-dash]

It's a 2007 Scion tC. I'm not too sure how much of it gets used regularly. I was looking at the major auto parts store and it seems they have the following 100A alternators: re-manufactured one for $100, premium remanufactured one for $140, a remanufactured one for $214, and a 100% new one for $240. All of these have $40 -$50 refundable core charge. The high output I mentioned above is $395 and they don't require a core charge. I'm looking at about $150 extra if I go for the higher output one.

That's a good point about the wiring and the fuses. I think I'm good with my current setup. However, if I wanted to go crazy and add more LiFePO4 batteries in the trunk, in addition to the 100Ah one already installed, then I would definitely look at upgrading the wire and fuses. My LiFePO4 battery does have a max continuous charge current of 100A, so that would be pretty interesting, but I would definitely have to upgrade the wiring and fuses if I tried something like that.

 

[Nigel]

I think I would just go for a re-manufactured one, I don't like the idea of a 100A charge rate, you would need some seriously expensive wires and fuses for that, but on the other hand, if you are spending a lot on a battery, it is a pity not to make full use of it!

It might be worth looking into the cause of the whine a little more, it may just need a new belt (would probably be more a clicking type noise), a new belt tensioner (I would think quite likely at that age), or new alternator brushes (would probably cause poor charging issues as well). On my car I have a slight whine, but that is from the aircon which is driven by the same belt. I wouldn't expect bearings to go on a Toyota, so I wouldn't expect a new alternator to be needed, an owners group should have the best ideas on that though.

 

[thomas-dash]

I took my car to AutoZone and they ran a free test on my alternator and said it's bad. Some of the videos I saw on YouTube mentioned the bearings go bad on the pulley shaft for this type of vehicle.

I'm going to go ahead and order a high output alternator and install it. I've always taken my car to the dealership for maintenance, but at this point I don't think it's worth it to continue doing so, except for things that aren't feasible to do at home, considering the age of the vehicle.

Even though the high output alternators are more expensive than the stock 100A alternators for my car, it'll probably be about the same or possibly cheaper than if I had the dealership install a new stock alternator. Of course I could just install a stock alternator myself, but I feel better about having a beefier alternator with the 18A DC/DC charger in the back. I would even feel comfortable with upgrading with my Victron charger to a 30A one, but I might need to upgrade the 6AWG cabling to 4AWG. I guess I could run an entirely new 4AWG cable down the passenger side and this would give me the option of running the 18A and 30A DC/DC chargers in tandem for a potential of 48A during bulk charging. This seems a little bit more achievable than getting the full 100A bulk charge rate.

I found a YouTube video online of guy who installed a high output alternator in the same model vehicle and he said the manufacturer of his alternator had instructions to run a 0AWG power cable from the alternator to the battery(and bigger fuses) and two 0AWG ground cables from the negative terminal of the battery to chassis grounds. He did have to install a slightly different belt because the pulley that came with his high output alternator was smaller than the OEM pulley.

 

[thomas-dash]

The new alternator arrived today. I think I’ll try to install it tomorrow. The pulley measured the same size as the existing one, so nothing to worry about there. Hopefully, everything goes smooth.

 

[LateralNW]

The new alternator arrived today. I think I’ll try to install it tomorrow. The pulley measured the same size as the existing one, so nothing to worry about there. Hopefully, everything goes smooth.


View attachment 60313

You'll find out soon enough but I would also check the plug is the same.

 

[kamkar]

Yeah check plug too before you pull old one, if thats good too, then it is only the offset of the pulley that might be wrong,,,,, i have no ides never tried to swap something like this out, but i assume belt placement can vary in between car brand / models.

 

[thomas-dash]

Yeah, it has the same plugs.

I was about to get started, but the floor jack I just bought doesn’t seem to have any hydraulic oil in it.

I saw some oil soaked into the carboard in the bottom of the box and the manual said to check the oil level as well.

I pulled the oil plug and it didn’t seem like there was any in it. The manual says it should be up to the bottom of the plug.

I suppose it could have leaked out due to the way as I was carrying it. However, when I pulled the oil plug there was a rush of air that left. You would think there would be a rush of air leaving if the oil leaked out due to the plug. Unless oil can leak out without letting the air out?

I might not need it, but I decided to change the serpentine belt as well and I’m not sure if I have enough space to put the belt on without taking the front passenger-side tire off.


Back to AutoZone to get some hydraulic oil.

 

[thomas-dash]

I spoke to an AutoZone employee yesterday and he said that the oil in the box was indicative of a jack failure. They didn't have another floor jack the same size in stock, so they told me to take the one I bought to another AutoZone close by.

On a separate note, it seems there's a recall on Duralast 2-ton jack stands. I try to buy a kit with a floor jack, jack stands, and a mechanic's creeper, but a recall notice popped up on the screen and said they couldn't sell it. Today I tried to buy 2-ton jack stands by themselves and the same thing happened. This explains why I couldn't find them listed on the AutoZone website when I knew I saw them on the shelf in the store. If you know anyone with Duralast 2-ton jack stands, then they might want to see if the jack stands are part of the recall.

I took the failed floor jack to the other store and had a funny discussion with the manager. He said the store I bought the floor jack from always sends the returns to his store. Anyways they said the same thing about it being failed and gave me the one they had in inventory. I didn't even have to ask them to open up the floor jack box from their store to make sure it hadn't failed as well they did it on their own.

I have the new alternator in place, but the new serpentine belt was going on no matter what I tried. There's a hydraulic tension that you pull towards you which gives you extra room length to slide the belt on and off. The belt I bought from AutoZone was 75.5 inches and it was listed as compatible with my car. I found some websites saying the OEM belt is a Bando 7PK1920. 1920 is the belt length in mm which is 75.5 inches.

I looked at the old belt and it had 7PK1935 on it which means it's 15mm longer than the belt I was trying to install. I can't remember if I've had the belt changed on my car or not, but I've always had the dealership repair it/ I'll assume the 7PK1935 belt is the right one and buy it. Hopefully it goes a lot smoother when I try to put it on.

 

[thomas-dash]

AutoZone refunded the shorter belt and I bought a 7PK1935 belt. It ended up being six dollars cheaper. The extra 15mm made a world of difference in getting the belt on. The car started up and I took it out for a 30 minute test drive without any issues. The whining noise is gone thankfully.

The pulley for the new alternator was slightly different than the pulley from the old alternator. The very outside of it seemed to have a wider diameter, but when I looked closer the inside grooves seemed to be the same diameter. I figured the inside grooves were what mattered since that's where the belt sits. On the old alternator the outside of it is kind of angled and flares out while the new one is mostly flat.



I still need to upgrade the engine wiring and fuses before I start pulling any serious amps from it. I'll probably hold off on that for now as I really want to get cameras installed on my side mirrors. Maybe at some point I'll tear apart the old alternator and see if I can determine what was going out on it. Based on my research it seems like the bearing is the most likely culprit. I might even try to rebuild it for fun.

Here's a pic of it installed with a new belt:

 

[kamkar]

Sweet.

But might i add,,,,,,, DAMN engineers repairing just about anything these days involve so much problems.

I have worked on house sized ship engines, and still if you had to do something simple, you had to loosen or take off 7 other things to be able to do it.
And then you have nothing but unused space on the rest of the huge engine.

In my little car, you have to be made of rubber and be a contortionist just to replace a bulb in the headlight, actually in the one side, taking out the battery make it a bit more easy.