horunner1x

My alternator is intermittently not charging. When it’s real cold in the morning my gauge says 12v and the lights are dim, blower fan barely turns, then after I drive for a bit and the engine gets up to temp the belt will squeal real bad and it’ll start charging again. Should I swap in a new one? Also occasionally does it when warm, idle will drop and the belt will squeal and the volt gauge will bounce around, then go back up to where it’s supposed to be. Belts are old, but that shouldn’t cause intermittent charging without also producing some kind of squeal right?

Blueman

Here's what I'd do, in order:
- Make sure your cables to the battery & alternator aren't frayed or loose. Fix as req'd.
- Make sure the belts are tight. Adjust as req'd.
- Replace belts that show any cracks (but that won't fix your issue)
- Make sure you don't have a coolant leak onto the alternator -- that'll interfere with its operation

If after that you still have issues, if the alternator is old (please, always tell us what truck model/year/engine/transmission you have), then likely it needs brushes. You can replace them (it's fairly easy), or just swap alternators.

87-4runner

O'Reilly autozone Napa
all should be able to test your alternator. For free.

scope103

Make sure your alternator belt is tight enough to turn the alternator. This is trivial to check; on a cold day when your voltage gauge reads less than 13v, pop the hood and look. If the belt is loose, it might not turn the alternator until it warms up, then it will squeal as it's trying to get a grip. Also, your alternator could then check out fine at the store.

87-4runner

It's kinda ironic to me that one of the most fluid sensitive, and vulnerable components in the engine bay is placed DOWN where almost any fluid leak goes right into the vents on the alternator...I wonder sometimes if engineers own stock in replacement part companies.
I've fried about 4 of them, alternators not engineers lol... Fortunately the rebuilt replacement has a lifetime warranty... ok I'm I'll get off my soap box lol.

Jimkola

We often commented about the wisdom of the cup holders right above or in front of the radio. Took them way too long to redesign.

if you do replace the alternator I’d hang onto the core if it’s a Denso unit. At least for a few months.

horunner1x

went through all the wires, checked everything with a volt meter, and everything pointed to the alternator so I just swapped it for a Napa unit. Fired right up this morning, no squeal, no bouncy volt meter, and I even got to have heat on my drive to work this morning. I do have the original denso alternator with 300k miles on it. Why hang onto the core?

old87yota

To be fair though, there should be NO fluids leaking...

87-4runner

Lol true a couple weren't my fault...
blown radiator hose...
front seal went out and covered it with oil
The PS pump leaking is on me...
Carwash and not covering the alternator was on me too...drrrr.

Jimkola

I’d hang on to the core just in case there’s issues with the reman. If you feel good already than go ahead and return.

horunner1x

ah, I get you. It was fine this morning, gauge read fine and lights were all bright and my heater worked. I noticed the gauge dancing a tiny bit on my drive home, barely moving but it was moving, never noticed it before with the old alternator. This is a 70amp as opposed to the oem manual trans 60amp, don’t know if that makes a difference. Should help a tiny bit when I put the three 100watt hella 4000s for desert trips. I’ll hang on to it for a bit, thanks for letting me know. Was going to get a denso reman from Napa but it would have taken a couple days to get here so I just got their house brand, didn’t wanna even try riding my motorcycle to work in this cold. When this goes I’ll get a denso reman.

RAD4Runner

Because, typically, when you buy a rebuilt alternator, you will be charged for "core" which and refunded when you turn in your old alternator. Did you buy brand-new NAPA and did it not have a core charge?

87-4runner

I don't think "brand new" is an option
but they do have a lifetime warranty...
Don't know how they do that on a piece of electronic equipment, but hey.

horunner1x

no they don’t offer a “brand new” at my local napa. I got their house brand that’s is the updated version of raylock. Not as good as a denso reman, but half the cost and has a lifetime warrantee. It seems to be fine the past couple days when it’s been low 30s-high 20s which is when the old one was failing. Now I’m getting a weird “zing” noise directly after I let off the key on cold startups so I think the starter is going out now too lol. Original Toyota with 300k miles on it.

RAD4Runner

I would take out and inspect for binding and excessive wear on gear. Also good time to replace the contact points.

ToyoDerp

Seriously, one should always go with Denso Reman for the extra price. Anything else is going to likely waste time having to pull it out and take it back to the store. It's not the most difficult alternator to get to, but still, how much is one's time worth? Anything non-oem with alternators these days is usually a losing gamble that it will last a long time. I have a Denso reman in my 1993 22re that's over 100,000 miles on the alt and runs perfect.

If you can send back the core for refund on the core charge, McGeorge has reman toyota alternators for much cheaper than NAPA. Not sure if this is the exact part number for your rig, but still gives an idea of price of $170.

https://toyotaparts.mcgeorgetoyota.c...bC1sNC1nYXM%3D

horunner1x

I would have done the denso reman if it were in stock. My local Napa has them for the same $180 with core charge so not much of a difference in price.

87-4runner

I'm really spoiled... we have a starter/ alternator shop in my home town that's awesome at rebuilding OEM parts... when he can, sometimes it just isn't possible though or cheaper to just get a reman with a lifetime warranty.

horunner1x

same here, I think I’m gonna take my denso to him instead of returning it for the $50.

Blueman

Most of the time it's brushes, and that's a fairly easy fix if you're handy enough to have removed the alternator in the first place.