1986 K10 Engine Noise - Help Needed! What could it be?

[Hiker3309]

Hey everyone, after tons of useful reads on here, Im finally writing my first post. I have a 86 K10 with a 305, Which i think is original, and its not sounding too healthy. I have this noise i cant diagnose. Can anyone tell me what this could be? Where is this noise coming from? I just replaced the fan clutch, thinking that was the issue, but no dice. Still awful noise. Stethoscoped everything I could and didn't find the cause. Any help would be amazing. Thanks!

Here are links to some videos of the noise...
https://youtu.be/OTk8F-2MmPQ

https://youtu.be/W2-TXK704Ko

[68gmsee]

Sounds like a dry bearing to me. Most likely the water pump.

[68gmsee]

Forgot to mention... Welcome to the site.

One other thing re. the noise. I usually look for the synchronized sound to a pulley movement. In other words the beat or rhythm of the sound in relation to the revolution of the pulley. Some pulleys turn faster than others and you can isolate it somewhat like that.

[truckdude239]

Pull the belts off one bu one and that will help you track it down

[Hiker3309]

Cool. Thanks so much guys! Went and got a new water pump today. Will hopefully be able to put it on tomorrow, if it's not raining. When doing, I'll remove belts one by one too and start in between to listen. Will update. Thanks again

[storm9c1]

If it isn't the water pump, try the alternator next.

[toolboxchev]

Originally Posted by storm9c1

If it isn't the water pump, try the alternator next.

X2we bluebloods make life easy

[Hiker3309]

Okay, so here's the update. I took the belts off one by one and started the truck to listen after removing each belt. First the belt to alternator, still noise, so not the alternator. Next the ac compressor, still heard it. Last belt is both water pump and power steering, sounds much better, but still something. I replaced the water pump anyways. I put a link to videos below of it running with no belts and running after I replaced the water pump. Damn it....the stupid noise is still there. I got out my stethoscope again...checked power steering pump, nothing. Then wedged it down behind the water pump and put it on the timing chain cover...could something in there be the culprit? It definitely how the most commotion and noise going on.

Any thoughts? Also, seems the truck has to warm up to start making this ruckis...And not sure if this is relevant, but I also hear a sound around 40-50 that sounds like grinding or metal on metal rubbing. It seems that when I step on the gas and the truck down shifts, it goes away, but as soon as I let off its back. Could be a completely different issue, but figured I mention it.

No belts
https://youtu.be/ooV2jywgCXw
Post new water pump, all belts
https://youtu.be/QJFwrg3QV7M

Thanks again for all the input! I really hope I can get this thing healthy again. This is the first time I've been so stumped with it.

[storm9c1]

OK, now that we've eliminated accessories, we need to dig deeper. That's a weird sound, I was sure it was an accessory. Dang.

The next thing I would suggest is to crawl under and see if it gets louder at the bellhousing area. The flexplate could have debris caught in it. If it is louder there, pull off the inspection cover. See if you see anything rubbing. Or even see if the cover itself is bent and rubbing. Seen that happen multiple times. And flexplate noises tend to transmit through the crank and sound like they are coming from different areas.

If it's not that, then yes, it could be the timing chain. The thrust bearing could be shot and your crank could be walking. Or the cam could be walking. Or something could have worked its way under the timing cover. If you are sure it's not coming from the flexplate or transmission area, then I guess you'll have to pull the timing cover...

[Hiker3309]

Dang is right!! Such a weird noise. So I have crawled under the truck 3 times over the last few days and listened to everything including the bellhousing and flexplate area. Everything sounds quite normal. The only place I here a louder sound is the timing chain cover. I guess I will try to remove everything and take the timing chain cover off this weekend.

Is there much I can do once in there...or is it sounding more and more like I am going to need an engine shop?

Thanks again!

[cadillac_al]

Grinding and metal on metal sound from timing chain cover eh? I had a 81 C10 305 and the timing chain wore a hole clean through the timing cover. I didn't hear any grinding but once it started leaking lots of oil I found the problem. I was surprised the timing chain didn't jump before that. It was wicked loose.