Help With a Noise

[1987 GMC Jimmy]

I've got a noise that I've never heard before that has me concerned. I took a video of it. It only does it the first thirty seconds after startup and only when it's cold. My belts are all properly tightened. My alternator pulley doesn't spin true, but it works and doesn't make noise with the belt off. I have a little engine tick that goes away after a few seconds only when it's cold, too. The thing that worries me the most is a failing oil pump, but I don't know if they make a noise.
The video quality sucks, but you can hear it just fine.

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[crazy4offroad]

Sounds like a bearing, waterpump or power steering pump

 

[1987 GMC Jimmy]

The water pump's new, and it was making the noise before I installed a new one. I've got some kind of pump whine, but it really only shows up when it's warm. It sounds a little like power steering, but it's not the full on groan, plus the pitch changes depending whether it's in park or gear. The fluid in the reservoir's good, but it wouldn't surprise me if it's on it's way out. I do notice that the assist cuts in and out the first few seconds you steer, but then it's fine. By bearing, are you talking about a connecting rod bearing or a bearing in an accessory?

 

[Charlie]

You could try removing one belt at a time and pinpoint where noise is coming from. I know that is a pain to do, but would tell you where it is.

 

[1987 GMC Jimmy]

Yeah, you're right. I may wait on that diagnostic a little. I just replaced the balancer and water pump so I had all that apart a few days ago. Ha, I gotta let the bruises, cuts, and punctures heal first.

 

[Honky Kong jr]

Spray some silicone spray on the belts immediately after start up. Did you replace the belts or just retention the old ones?

 

[1987 GMC Jimmy]

I retensioned the old ones. I just went and double checked them. The alternator belt is really twangy, but I cranked that alternator as far as it would go because it doing that same stuff before I fixed the balancer. When I started it, though, it didn't make the noise. It had probably sat for a six hours. The V belts look good, though. I'll do the silicone for the alternator belt for sure.

 

[Charlie]

Another old school test is to have someone start truck, use a wooden yardstick or similar stick of wood and place it on each component and put your ear to other end to hear where the noise is coming from. You will have to be quick and keep it away from belts, fan, etc. and that should locate noise only if you are quick enough since it only lasts about 30 seconds or so. It may sound weird, but it works. Good luck.

 

[1987 GMC Jimmy]

I'll definitely give that one a go, too. Thanks.

 

[rt66paul]

Good video with a yardstick in your ear or it didn't happen.

 

[CSFJ]

Or spend the 2 or 3 dollars and get a mechanics stethoscope from china freight.

 

[Snoots]

Take the belt off of the ac compressor. If squeak is still there, I'd bet on the alternator bearing. Just my 2 cents.

 

[78C10BigTen]

Sounds to me like the ac compressor

 

[89Suburban]

Torque converter or pump?

 

[1987 GMC Jimmy]

I got a mechanic's stethoscope to do it. The wood trick was a start, but I couldn't hear what I needed to. The noise that always hangs around (wah-wah-wah) is coming from the power steering. It was best heard at the bracket not the reservoir, though. I guess it makes sense due to dissipation through the fluid. I'm almost certain the initial noise is belt related either with the PS or with the alternator. With the belt off, the alternator pulley and fan has a lot of play in it, kind of like a top that's about to quit spinning. The belt flops a good bit even if it's really tight. It charges well and doesn't make any noise, though. Even with the stethoscope it sounds good. I might try again to race to hear the noise at cold startup. Thanks for the replies up to this point, especially @89Suburban who we don't see much these days. I tried using a turkey baster to flush the PS pump in the past, but it's not a good tool for that. I'm going to try again with a bulb siphoner from Walmart.