99 K3500 Squeal/whine/rattle/whir

dogsrme · August 9, 2008

About a month ago, I started my 1999 K3500 7.4l at 6am (which I never do), and the belt started squealing like crazy. Restarted a couple times, and drove it anyway, thinking it was the dew (and it's not a morning person, like me) and would dry out. It just got louder and sounded like a high-pitched metal grinding noise. So I hit the belt with wd40 to see if it would shut it up. It did for a while, then came back....so I took it to the car wash (since there's alot of dust where I live and I usually go every week, but hadn't for 3 weeks, so figured maybe that's why it was acting up out of the blue). Then it's quiet for almost a month. Then I start it in the am again the other day, and it's back! I used belt dressing this time, which lasted one trip, then back to the wd40 and carwash trick to shut it up. Only this time it was worse after the car wash and sounded like a pop can was stuck in the fan (nothing's there). It's a scary screeching metal noise, but wd40 makes it purr like a kitten. Last time, there was no effect on my battery or temp gauges or steering, so I figured my water pump, alternator, and power steering pump were fine. Turning the ac off and on made no difference. This time, the battery gauge drops down when you first spray it (and in the car wash), which it's never done before--so I figured the belt is slipping from the belt dressing/wd40 combo. Now running the ac drags the battery down as well. Now what do I do? Do alternators make this noise when they are dying? Or ac compressors? Or????? Makes sense that something was going out in the first place, because why else would a quiet, perfectly good belt start shrieking out of the blue? But why did the alternator work fine last time and it stayed quiet for a month, and now it sounds like a train wreck and can't keep up? Is my belt going to snap off any minute? They say not to use wd40 cuz it dries out the bearings, well what bearings are these and is there a way to relube them? I live in CA, so any trip to a shop is $1000.00 just to say hello to them, much less "help!" So any ideas would be appreciated. If the power steering/water pump were going out, wouldn't I have steering/temp. problems? Also, my service engine soon light came on last week too--is that just emissions or could it be related to this? Thanks, please help me!

minibike132 · August 13, 2008

It's been a few days since this post went up and no one is answering so I'll shoot one at ya. You may have even moved on and found a fix. I know somone will argue with me here but putting any lubricant on the belt is a bad idea. It only masks the problem and creates more as you can see. The noise is a belt minorly slipping to a audible point. Adding WD40 or dressing or whatever just makes it slip fast enough to not be audible...for a while. Then that lube heats up and bakes into the pulleys and it is a bitch to get out. I have a little trick that usually works but not always. First I spray the crap out of the belt with something to clean up and dry out the belt and pulleys, usually brake cleaner. Then I get some valve grinding compound and coat as much of the belts and pulleys that I can get at. If your not familliar with it (nobody is who grinds valves anymore) most parts stores will carry it in a tube or tub. It kind of looks like antisieze with sand in it. That is not the what it is, do not go spreading antisieze on your belts, that's just what it looks like. It was a trick an old guy taught me for when they start squeeking, usually if the belt is not bad and none of the bearings are bad the culprit is a little surface rust on the pulleys. The valve grinding compound cleans that up without adversly reacting with the rubber. In that case we only put a little on both sides of the belt. I find it works for cleaning the dressing crap out of the pulleys.

Any way spread that crap all around on the belt and pulleys then start the engine and let it run for a bit. Rev the engine and wear that crap in. Depending on how everything looks I might do it again. After that remove the belt and run a rag over all the pulleys to remove any excess compound and install a NEW belt. The old one is junk don't even bother trying to save it.

If this doesn't work and it sometimes does not I take the time to access all of the pulleys and clean them off with a wire brush then install a new belt. This is the right way to do it and you may just want to go this route but I find the other way works alot of the time.

Do alternators make this noise when they are dying? Or ac compressors?

Yep any bearing in the pulley system will make this noise when dying but if it goes away when you spray the belt it isn't a bearing, they are all sealed.

Also, my service engine soon light came on last week too--is that just emissions or could it be related to this? Thanks, please help me!

Might be related might not, I would wait to address the light till you are mechanically sound.

Good luck, let us know what happens.

dogsrme · August 14, 2008

Thanks!!!

pennzoil29 · August 14, 2008

I was told to never put any kind of dressing on a serp belt. It could cause it to slip off of the idler pully's. I had an annoying sqeak a couple years back that would just not go away. I took the old belt off and cleaned the pully's real good, and then installed a Gatorback belt. The noise went away, and I haven't heard it since.

95Sierra2500 · August 14, 2008

You know, my dad had a squeal at start up on his '94, and one day it just wouldn't go away. The volt gage also didn't want to come up. Finally the squeal stopped and everything came up just fine. We got home and I had him re-start the truck, and I'll be damned if the belt wasn't moving with the crank pulley. Turns out when he'd had it serviced the last time he had issues returning from a hunting trip out west (pulley locked up and fell off - never made a sound until the clunk), the idiots at the shop completely ignored the belt routing diagram RIGHT THERE ON THE FAN SHROUD and routed it wrong so that only 5-10* of belt were touching the crank pulley. Got him the right belt (they'd gotten a longer one because the right one 'wouldn't fit') and he hasn't had a problem since.