synergy58

We have a loud, strange noise that comes and goes, pretty frequently now. It started out only happening once in a while, but now it's happening every time we drive it and it seams to be getting louder. It sounds like a loud whistling noise like a freight train now; before it almost sounded like a vacuum type of noise. It doesn't sound mechanical, like metal rubbing or grinding, more like a hum whistle squalling sound, loud. Gets everyone's attention.

I just ran it by a mechanic and he said he had no clue, would have to get into it, but not till next week, Thursday at the earliest. I can't wait. HELP!

We had the AC on. I shut it off completely when the noise started, but it had no impact; turning the fan speed up and down and off made no impact. I idled the engine up during the noise and that made no difference; the noise still remained constant and steady, with the same pitch. I looked everywhere and can see nothing out of the norm.

Anyone have any idea, have ever had this happen to you before?

Thanks!

synergy58

I found a loose bolt at the bottom of the power steering pump, but can't figure out how to get to it. Obviously I need to tighten this. I'm not sure it this is the cause of the noise though.

I know chasing noises is like the worst thing to do, just about, but...
Anyone with ideas?

1976gmc20

That is really strange.

synergy58

Yes, strange.

If the belt is bad, would it make this constant noise, intermittently, and not change pitch, while increasing and decreasing the rpm's? or turning the ac on and off?

Could it be a pulley? I'm not sure because the noise remains constant.

Eisenschwein

Odd. A couple of things that I've had make horrible, hard to trace noises are, 1) Idler Pulley. It is in the belt system and if the bearing starts to go out, it will make a horrible racket. 2) Power Steering Pump... pretty obvious because it gets loud when you turn your steering wheel. 3) Loose Flywheel... Not too common, and probably not your problem but it makes a horrible racket and changes with RPM. But my money would be on the Idler Pulley.

1976gmc20

From my 40++ years of working with various engines (but mostly GM), I can't think of any non-driveline noise that wouldn't change with engine rpm, except for the radio. You've already ruled out the heater fan, unless it's stuck in one speed regardless of the switch.


What about your electric cooling fan ??? It should be Off unless AC is on or the engine is pretty warm.

synergy58

Sooooo, yup, noise pitch doesn't change with rpm increase or decrease, and I believe it's gotten louder just in the last few days, and its occurring more often as I drive. I'm talking about short drives too, like less than 10 miles total. It does seam to happen once the engine reaches operating temp, as it gets warmer. When I first start up and drive the first few miles, I don't hear anything. I shut it off, wait about 15-20 minutes, then start up and drive off, and then after about 2-3 miles, it gives its first vocal cry...then after 30 seconds or so, it stops. I drive for a few more miles, nothing. I stop, shut it off, no noise. After another 20-30 minutes, I take off, about a mile down the road, it sounds off, stops after a couple of miles. Then I go a block down the road, right as I'm going through a secure check point, it sounds off louder than ever as I approach the gate security force Airman. He says "your Jeep must not like me". It's freaking embarrassing to me!

My wife says she's not driving it until I get it fixed, for real!

Man, what a PITA! Makes me want to just shoot it!
LOL!

I will check the electric fan first thing in the am. Thanks!

synergy58

As I mentioned, the power steering pump has a loose bolt. I can't reach it unless I take the whole damn thing off, which I WILL do in the AM. I'm going to replace the belt, and I guess the Idler pulley while I'm doing all this, what do you think? Yes?

We bought this jeep used, from a second owner. He didn't describe it accurately when on the phone and over email. I traveled 535 miles oneway to get it. I didn't check EVERYTHING as well as I should have. Of course, he was a pretty smooth talker, a bit on the forceful side, but hey...I bought it.

Wife and I do enjoy driving it, WHEN ITS NOT SOUNDING OFF! LOL!

Geeze, I gotta get this fixed!

1976gmc20

You should be able to start/stop the electric cooling fan with a cold engine by switching to/from AC or defroster, assuming it's working properly.


Also, there is a connector about six inches from the fan that you could unplug just to see if the screeching stops when the engine is hot, which is probably better than shooting it.


My electric fan wasn't working at all until I cleaned that connector. Now it roars when the AC is on. I'm thinking about getting another fan and mounting it on the tailgate as a pusher prop to see if it helps the gas mileage

El_Guapo

Sounds like a bearing to me - One that hasn't made it all the way to frozen yet, but is undergoing one of those poorly thought out engineering terms, "ball skid". Mine did something similar when the A/C clutch bearing started going out.

Here's where down and dirty diagnostics come into play - get one of those foot and a half long screwdrivers, put the blade up to components and your ear to the handle and listen for a grinding sound. Remove your serpentine belt and run it for a few minutes. See if the noise goes away. If it does, start manually turning components and feel for roughness. I'd put money on either the A/C clutch or the idler/tensioner pulley.

Another trick if you've got one is to run an IR temp gun across the various bearings and look for a change in heat signature. Typically if a bearing has reached 250 degrees, it's done for.

synergy58

Cool idea, the screwdriver bit! I'll do that this AM. I'm going to change the belt, because its worn, and I'll do the idler pulley, because I'm doing the belt, so might as well. As for the AC clutch, well I guess I'll check that before getting too carried away with replacing everything.

The problem is, the noise doesn't always start up when I want it to; it comes and goes.

Thanks for the help!

Jeep Driver

Harmonic balancer is slipping.

synergy58

AC compressor. Now, I have to learn how to fix that. Hmmm?

El_Guapo

Odds are that it is just the clutch bearing - easy as pie without much in the way of specialty tools. You can use a regular 3 jaw in place of the specialized plate puller, but the puller is cheap if you are so inclined. I think Autozone and Oreilly even rent them for those unlike me that don't reside in the middle of nowhere.

Here is the manual (For most XJ's - I've never seen one that wasn't a Sanden): http://www.sanden.com/productlibrary...uide_Rev_2.pdf If you've got one of the other variants, you can get the manual off of www.sanden.com

Just remove the belt and the 4 mounting bolts and you can stand it on the back end without worrying about refrigerant loss or introducing air to the system. Sometimes the bearing is staked to the housing, so you'll have to use a die grinder or Dremel to get rid of the staking. On mine I was able to carefully cut the race with a stone on the die grinder and pop it right out. Put the new one in the coldest freezer you can find overnight before installing it and it will shrink a mil or so.

You can find just the bearing through a lot of sources, or if you want to go for the whole hog on the clutch there is a guy on EBay that sells the whole kit for around $80 (bearing, shims and plate). Goes by "allforauto".

As an aside, try and make sure the bearing you get is from a reputable manufacturer, such as Timken, SKF, *** or NSK.

El_Guapo

I'll look and see if I can find the bearing P/N for you - I usually write them down in case something like this comes along.