car help, high pitched noise

[hybridxx]

alright, so a 2 days ago my car started making this high pitched noise.
i drive a nissan 240sx.
almost sounds like a semi truck.
so i figured the alternator was going bad. my lights would go bright whenever i revved my car etc..
at first it wasn't to bad, it would only get really loud when i got to the higher rpms.
then it started doing it right when i would turn on the car. would do it for a few seconds then just go down, but continue to do it at high speeds.

so i went and switched out the alternator(the pulley on the old one seemed to be super loose)

started up fine and everything, the sound wouldnt happen anymore..but when i drove away the noise comes back at around 2500, the same semi truck sound noise i was mention, then at about 3500, it gets really high pitched. i dunno wtf it is..thought it was the alternator for sure. its quite aggravating. the water pump is less then a month old, maybe thinking it could be the power steering pump? or one of the things connected to the stupid belts..

could it be one of the pulleys or anything?
thanks in advanced.

[DEXSPEED]

try prestone belt dressing to condition your belts or change it.

[Apex]

I was thinking a loose belt or the belts going bad too.

May be worth investing in one of those cheap automotive stethoscope's. It makes pinpointing issues much easier. I used one to find a bad lifter on my old mustang. They work well. Get one and start moving around the car. I also found a bad idler pulley on my wife's mustang with it. Well worth the 10 or so bucks it costs to get one.

[Sailariel]

I'm thinking a glazed belt and/or glazed pulleys. Certainly, some belt dressing directed at the pulleys and the belt would not hurt. If that doesn't solve the problem, a stethoscope like Mark suggested, would go a long way in diagnosing the problem. Back in the 60s, when a lot of us were riding Brit bikes, we would use a stethoscope and listen to the valves after they were properly adjusted to get a baseline as to how they should sound. Then, periodically we would give a listen, and if they sounded different, we would adjust them. Life was so much simpler then.

[hybridxx]

ive heard nothing but horror stories about belt dressing :[.
u guys have any experiences with it?

and how exactly does a stethoscope work?

[austexjg]

ive heard nothing but horror stories about belt dressing :[.

+1

[Sailariel]

I don't use belt dressings as a rule. On the older cars with V Belts, they worked OK. I do use them on the V belts on my sailboat auxiliary and genset. On the newer serpentine belts, it is a diagnostic tool. If after the dressing is applied, the squealing stops. Replace the belt.

[00NissanNinja]

What year 240sx? I think it may be the belt as well make sure they are on tight(did you mark the alternator adjustment bolts?). If this is the 240sx with the ka24de engine try checking the upper (I think upper) timing chain guide, I heard that makes a lot of noise on the ka when it comes lose (haven't experienced that myself but I've seen others with the issue). It doesn't need to be on the car supposedly though I would keep it.

[hybridxx]

yeah, its a ka24de engine.
and what do u mean by marking the alternator adjustment bolt?
ill check the riming chain tho. thanks.

[Apex]

I also have a long screwdriver I use as a stethoscope when I don't feel like digging the real one out. Stethoscope works better though.

Well some people mark where the bolts are on the alternator because it would sometimes loosen up over time. My old mustang used to do that. I'd mark it as a reference, if it went and moved, I'd know it immediately.

[00NissanNinja]

Originally Posted by Apex

Well some people mark where the bolts are on the alternator because it would sometimes loosen up over time. My old mustang used to do that. I'd mark it as a reference, if it went and moved, I'd know it immediately.

That is what I meant. Its a good practice to mark the adjusting bolt first to make sure you are near where you need the tightness of the belt to be. Thats what I do with my U13 which has the same engine. So check the belt tightness first and see if the noise is near the timing chain or not using the methods others said(cause getting to the timing chain may be a bit of a pain) then check the timing chain guide since it sometimes gets lose and rattles or lays on the timing chain.

[rockNroll]

Hold on there hoss! Start by removing your belts, one atta time. You need to determine if the noise is a belt driven item or not. Drive the car down the street and back after each belt removal to see if the noise was being driven by the last belt removed. Remove the first belt, road test. If the noise is still present, remove the next belt and road test... git it? If removing a belt rids you of the noise, then we're half way there! Now, what does said belt run? Make sure your road test without a water pump belt is short

Report back with your findings

[CThunder-blue]

Originally Posted by rockNroll

Hold on there hoss! Start by removing your belts, one atta time. You need to determine if the noise is a belt driven item or not. Drive the car down the street and back after each belt removal to see if the noise was being driven by the last belt removed. Remove the first belt, road test. If the noise is still present, remove the next belt and road test... git it? If removing a belt rids you of the noise, then we're half way there! Now, what does said belt run? Make sure your road test without a water pump belt is short

Report back with your findings

This is the scariest advice I've seen. Please don't attempt to drive the car like this.

First off, does the high pitched sound like metal on metal or more like a squeal? If the alternator pulley was wobbling, there might be a chance your crank pulley is also wobbling. Check around it to see if it's making contact with your motor when you rev. Just have someone rev the engine while you listen for it.

There's nothing wrong with belt dressing. I've used it and with no ill effects. you just need to follow the directions. IE, don't spray it on your alternator and don't wash the belt with it. If you spray a little and the sound goes away, it's most likely a belt problem. You either need to retention the belt or replace it if you reused the old one.

[Nemesis]

Originally Posted by CThunder-blue

This is the scariest advice I've seen. Please don't attempt to drive the car like this.

First off, does the high pitched sound like metal on metal or more like a squeal? If the alternator pulley was wobbling, there might be a chance your crank pulley is also wobbling. Check around it to see if it's making contact with your motor when you rev. Just have someone rev the engine while you listen for it.

There's nothing wrong with belt dressing. I've used it and with no ill effects. you just need to follow the directions. IE, don't spray it on your alternator and don't wash the belt with it. If you spray a little and the sound goes away, it's most likely a belt problem. You either need to retention the belt or replace it if you reused the old one.

Nope, not the scariest and he is on the track but I would tweak his suggestion.

I wouldn't recommend driving it. Just take off the drive belts (alternator, A/C, Power Steering belts) and then put one belt at a time and turn the car on. You'll immediately be able to tell which belt is making the squeaking/high pitched noise.

[rockNroll]

Originally Posted by CThunder-blue

This is the scariest advice I've seen. Please don't attempt to drive the car like this.

First off, does the high pitched sound like metal on metal or more like a squeal? If the alternator pulley was wobbling, there might be a chance your crank pulley is also wobbling. Check around it to see if it's making contact with your motor when you rev. Just have someone rev the engine while you listen for it.

There's nothing wrong with belt dressing. I've used it and with no ill effects. you just need to follow the directions. IE, don't spray it on your alternator and don't wash the belt with it. If you spray a little and the sound goes away, it's most likely a belt problem. You either need to retention the belt or replace it if you reused the old one.

This isn't scary at all. This is the proper way to diagnose his noise.

However the car needs to be operated in order to recreate his symptom... that's how it needs to be operated after removing each belt. If it will make the noise while not driving, that's fine, but if the car has to be driven, then that's what is needed. He only mentions the 2500rpm and 3500rpm and he's driving it. He didn't say wether or not it will make the noise while sitting still.

Belt dressing is total crap and fixes nothing. It only masks a symptom caused by a problem that isn't being addressed. If his noise isn't the actual belt, he may now have to run a "too tight" belt tension to keep his belt from making noise now that it has that crap on it. Now we wear out things like alternator bearing, power steering pump bearings, water pump bearings... etc.

If the noise was a belt, he most likely would hear is upon acceleration (slapping the gas pedal) ... belt noises don't typically come on at a higher rpm... that's usually a belt driven component... or something not even related to his belts/pullies etc.

[HKr1]

Originally Posted by rockNroll

This isn't scary at all. This is the proper way to diagnose his noise.

It's scary For being the proper way of doing things, its the first I ever heard of it

If its the belt squealing on a pulley, you can see that pulley not spinning up to the speed of the belt when its making noise. <atleast everytime time I ever seen/heard one squealing

[rockNroll]

Originally Posted by HKr1

It's scary For being the proper way of doing things, its the first I ever heard of it

If its the belt squealing on a pulley, you can see that pulley not spinning up to the speed of the belt when its making noise. <atleast everytime time I ever seen/heard one squealing

Why are you scared? As long as his runs are brief, he doesn't run the engine long enough without a water pump belt to over heat it.. why be scared? Do you even know why this scares you? What's gonna happen? I have used this method for better than 20 years and off the top of my head, I'll say that most of the other master techs I know do this too. None of us are very scared while doin it. It's easy and efficient.

[Nemesis]

I'd have to agree...I wouldn't run it under load. I'd do it the way I suggested it. You can put the car on jacks and rev it to 2500-3500 rpms.

My personal experience & with others on car forums is that they suggested the same thing I did. But I'm sure that's going to vary from forum to forum, people to people.

I'd rather have the car break down in my lot than on the road.

[rockNroll]

Originally Posted by Nemesis

I'd have to agree...I wouldn't run it under load. I'd do it the way I suggested it. You can put the car on jacks and rev it to 2500-3500 rpms.

My personal experience & with others on car forums is that they suggested the same thing I did. But I'm sure that's going to vary from forum to forum, people to people.

I'd rather have the car break down in my lot than on the road.

That depends... if his symptom only occurs under load, then it needs to be run under load. This is simple every day stuff.

[tjkamper]

Yes, There is nothing wrong with driving without belts as a diagnostic measure. I have done it many times. Just remember, your not taking a road trip. Just drive around the block.

[Nemesis]

Originally Posted by rockNroll

That depends... if his symptom only occurs under load, then it needs to be run under load. This is simple every day stuff.

Well, that's good to know. Although, last time I tried this (not to diagnose issues with belts) around my block the car broke down and I had to push the damn thing back to my house and I swore never again.

Correct me if I'm wrong but putting it in "P" or "N" is not under load. Placing it in "D" & "R" is under load per the service manual. Is this not correct?

[HKr1]

Originally Posted by rockNroll

Why are you scared? As long as his runs are brief, he doesn't run the engine long enough without a water pump belt to over heat it.. why be scared? Do you even know why this scares you? What's gonna happen? I have used this method for better than 20 years and off the top of my head, I'll say that most of the other master techs I know do this too. None of us are very scared while doin it. It's easy and efficient.

Now days, one belt runs everything.... so its just a waste of time.
Was flipping thu the channels this past weekend, two guys garage had an episode on removing the belt. I just had to laugh, talking about it.... and heres a show. At the end of the street, the temp gauge was pegged. They kept driving it, steering it the best he could

http://www.twoguysgarage.com/index.p...on-9&Itemid=77

[rockNroll]

Originally Posted by HKr1

Now days, one belt runs everything.... so its just a waste of time.
Was flipping thu the channels this past weekend, two guys garage had an episode on removing the belt. I just had to laugh, talking about it.... and heres a show. At the end of the street, the temp gauge was pegged. They kept driving it, steering it the best he could

http://www.twoguysgarage.com/index.p...on-9&Itemid=77

Many Asians have two belts. Many GM trucks have two belts. Some domestic have two belts, but mostly one unless supercharged.