HELP me figure out what this sound is (video)

[94FSblazer]

vehicle: 1994 Chevy Blazer 350 TBI

Hey guys,
First post on here, but I've been reading posts on here for a long time. Figured it was time I actually join.

Ive had this sound coming from my engine for awhile now. It seems to have gotten louder recently. Any idea where I should start to look for the problem?

Sometimes it sounds like its coming from under the intake, other times it sounds like its coming from around the belt. all my pulleys are tight tho.

The knocking is sometimes constant, and other times its like in the video where its off and on. The video starts with me starting up the warm engine, but you start to hear the noise about 22 seconds in then off and on after that. Another good clip of it is around 55sec or so.

Let me know what you think and where I should start. Its driving me crazy, but I haven't been able to tear anything down for awhile due to a shattered arm.

Thanks for any input!

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[89RCLB]

Really hard to tell from the video...maybe try removing the belt and see if the noise goes away.

 

[Hipster]

Get a mechanics stethoscope, a piece of heater hose, a long screwdriver with your ear up to it and try to pin point it a little better. I would pull the belt and run it for a minute and see if it eliminates itself. Spin everything by hand if you haven't. When it first started sounded like a rod knock. Other things, loose impeller in the water pump alt bearings. Steering pump bearings. Does the oil look metallic on the dipstick?

 

[94FSblazer]

Get a mechanics stethoscope, a piece of heater hose, a long screwdriver with your ear up to it and try to pin point it a little better. I would pull the belt and run it for a minute and see if it eliminates itself. Spin everything by hand if you haven't. When it first started sounded like a rod knock. Other things, loose impeller in the water pump alt bearings. Steering pump bearings. Does the oil look metallic on the dipstick?

Ill try to use something to pin point a little better. Its pretty loud when it really gets going. But it isn't constantly making this sound? Ill take off the belt when I have my other arm available to help. When I had it off about 6 months ago, everything spun fine. But I do not remember starting it up and noticing anything. Ill have to do that. Hoping it isn't something too bad

 

[kennythewelder]

Get a mechanics stethoscope, a piece of heater hose, a long screwdriver with your ear up to it and try to pin point it a little better. I would pull the belt and run it for a minute and see if it eliminates itself. Spin everything by hand if you haven't. When it first started sounded like a rod knock. Other things, loose impeller in the water pump alt bearings. Steering pump bearings. Does the oil look metallic on the dipstick?

X2,,, welcome to the forum

 

[94FSblazer]

O yeah, no metallic on the dipstick. oil looks good. It is only 600 miles old tho

 

[Hipster]

This a warm start, does it make hella racket starting cold?

 

[yeehoo]

I have a similar sound,4.3 tbi, 217k, except, its at the back of the engine on the passenger side and it's only when getting on it. Guy on youtube claims to have filtered glitter from the oil in a 305 7 years ago and ever since with no sound and engine is still running fine. I popped the valve covers on mine today. They looked good pretty much like they had just been put in, nothing anywhere near clogged. I took it out and tried to break it or get it to spin today. Still running fine. Idles good with 20 psi of pressure at warm idle. Intake, valve covers, oil pan, oil cooler all look like new gaskets. It is leaking from rear main. Recent purchase truck. I have fixed rust rotted muffler and chattering belt tensioner. Plan now is to just keep driving it until it blows and then get a cme performance motor.

 

[94FSblazer]

Good news!

Got a mechanics stethoscope, and figured out that it is just the tensioner pulley making the noise. put the stethoscope on the bolt and could hear it very clearly. put it other areas and could not hear anything. so time to get a new pulley. Should I just go ahead and replace them all?

Also, I want to get a new tensioner bolt, but can't seem to find it anywhere. Any advice on that?

Side note, really glad I picked up that stethoscope! Great tool, never thought of getting it, but it pinpoints sounds great!

Thanks for the help! Now time to replace, and move onto the next problem. hmm find leaking oil? replace intake gasket? fix leaking power steering? and the list goes on. So many choices!

 

[kennythewelder]

If all that is bad, is the bearings inside of the pulley, this is all you need to change, but it is easier to just change out the whole pulley. As for the bolt, as long as it is still in good shape, there is no need to replace it. One of the things we do where I work, is press bearings. From little bearings, to bearings that you need a crane to lift. As long as the part that you are replacing the bearings on, is good, then you can just replace the bearings.