new noise in my engine!

I have a new noise in my truck now. It’s hard to describe but it sounds kind of like a high pitch humming noise. When I start my truck it’s really loud and as I drive and warm the engine up is dies down but doesn’t go away. I’m think it might be the alternator, I could be wrong. It seemed to start as it got colder out. Any idea???

The best way that I've found to trace noises like that is take a spray bottle of wd40 with the straw fitting on, and when you hear the noise pop the hood, and carefully spray all the exposed bearings like your alternator.

The noise will stop almost instantly.

Never wear loose clothing while doing this, but you knew that already.

Another thing that it might be is the engine it's self if your running thick engine oil. You should be running 5/30 for the winter.

its a 98 4.3 engine just incase you needed to know :D


the oil is fine. wont wd40 mess up the alternator? The reason behind me thinking its the alternator is because I run a system off it probably puts alot of stress on it, its still the factory one from 98 when I got the truck.

:screwy: You said that you had an audio system. Does your headlights dim when your bass hits hard? If so you may want to invest in a farad capacator and this will relieve the stress on your altenator. I've put one on my s-10 and i have a few left over from when i used to manage an audio store.

just a quick squirt of wd40 on the alternators bearings shouldn't hurt the bearings, and if it's instantly quiet you know to save up for a re-built one.

Some people use WD40 as electrical contact cleaner, although I prefer something less oily like methol hydrate, or ether (when there is no chance of any spark)

You can run a fairly powerful sound system off a stock alternator. If your worried about it not having enough juice it's inexpensive to have the charging system's output with your stereo blasting.

I agree with autohelper about the farad capacator plus A second battery is a good idea too, if you can fit it somewhere

Before you go putting wd40 on your alternator I would check the idler and tensioner pulleys. These tend to go bad on these trucks and are easy to replace. Just take the belt off, squirt some wd40 on their bearings while spinning the pulley. Put the belt back on and start-r-up. If that doesn't work then you can go to the alternator. Good luck man.

There is no dimming of the lights any where, the battery indicator moves slighty but very little.

I did try putting wd40 on the alternator and the noise went away, so i believe the bearings are starting to go.

Wd 40 is not a lub! dont be using it as one, if you want to lube the alt berrings get lub, soo many people mistake wd 40 as a lube and its just a degreaser... but yet the hum could be alt, it also could be your cat, mine hums, if you notice a sulfar smell with it then your cat has cloggged up and needs replaced/a stright pipe and an 02 sencor cheater from jegs.com

its the alternator in this case, once i through wd40 on it the noise stopped.. haha after that i just throw some regular oil on it.. for 6 years that puppy has been making my system pound i wouldnt be surprised if its time for a new one

That whirring noise is usally the alternator.

Mine did that in the start of the winter last year.

Wd 40 is not a lub! dont be using it as one, if you want to lube the alt berrings get lub, soo many people mistake wd 40 as a lube and its just a degreaser... but yet the hum could be alt, it also could be your cat, mine hums, if you notice a sulfar smell with it then your cat has cloggged up and needs replaced/a stright pipe and an 02 sencor cheater from jegs.com

Wd40 isn't a degreaser either is is simply a rust prevention liquid wd stands for water dispersment and 40 is the amount of times it took to prefect the formula. but it does work good as a lube just not for a long periods of time.

Wd40 isn't a degreaser either is is simply a rust prevention liquid wd stands for water dispersment and 40 is the amount of times it took to prefect the formula. but it does work good as a lube just not for a long periods of time.

WD40 isn't a lube either.

Wd40 isn't a degreaser either is is simply a rust prevention liquid wd stands for water dispersment and 40 is the amount of times it took to prefect the formula. but it does work good as a lube just not for a long periods of time.

It isn't a lube either.

Nor should it even be considered a lube for short periods.

any liqued has less friction then surface to surface, its called Fluid friction, but i have no intention of useing water in my crank case over oil, nor should wd 40 be used as a lube for any amount of time

i'm not telling you to lube the alternator bearing with it because i agree you should do it right but, i use it to lube pretty much anything that isn't engine related i haven't found a deference between it and white lithium on my door hinges and when i was a kid i used it on my bike chain every time i oiled it so even though like i said it isn't a lube it works as one

i'm not telling you to lube the alternator bearing with it because i agree you should do it right but, i use it to lube pretty much anything that isn't engine related i haven't found a deference between it and white lithium on my door hinges and when i was a kid i used it on my bike chain every time i oiled it so even though like i said it isn't a lube it works as one

That is all in your head because IT ISN"T A LUBE.

It has no lubricational properties.

It is used as a penetrating fluid or a water displacer.

It is WAY to thin to lubricate anything.

http://www.wd40.com/Brands/wd40_big_blast.html i beg to differ

http://www.wd40.com/Brands/wd40_big_blast.html i beg to differ

TI cannot be considered a serious lubricant.

Please stop bucking my advice.

For christ sakes, it is more of a solvent than a lubricant.

Use it if you want, it will be gone in a week or so, I will use my lubricating oil which will stay for months.