Sbc 350 engine noise - Chevelle Tech
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post #1 of 12 (permalink) Old Jul 8th, 19, 9:12 AM Thread Starter
 
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Sbc 350 engine noise

Hey guys I know this isn’t a Chevelle related question but I’m desperate for answers. I’m pretty sure the engine is ruined but let me know what you guys think. Quick run down of what happened was I snapped my v-belt on my 350 small block and the car was overheating so I pulled over to let the fans run and cool down and replace belt. On the way home it was making a nasty scoring sound, similar to a belt squeal and didn’t think much about it and figured I’d take a look when I got it home just to find that this noise was coming internally from in the motor. Like piston rings scoring the cylinder wall? Here’s a link to the video on YouTube. Any one have any ideas???? https://m.youtube.com/watch?v=REltK6uqYVI
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post #2 of 12 (permalink) Old Jul 8th, 19, 10:11 AM
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Ed
 
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Re: Sbc 350 engine noise

Just a W.A.G. doesn't sound internal.
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post #3 of 12 (permalink) Old Jul 8th, 19, 10:24 AM
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Hank
 
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Re: Sbc 350 engine noise

It still sounds like a belt. With the car off try and turn the alternator pulley by hand. If it turns the belt is too loose. It's hard to tell but the belt looks like it rides low in the water pump pulley. Check the PS belt too.
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post #4 of 12 (permalink) Old Jul 8th, 19, 11:12 AM
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Harry
 
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Re: Sbc 350 engine noise

It does not sound like an internal noise to me. It sounds like squealing, like a belt. Check for a new vacuum leak, belt squeaking, or a bad bearing in one of your accessory pulleys. Also, make sure you did not blow a head gasket and that noise is air or water moving where it should not. How is your oil and coolant ? Look under that breather in the valve cover and check your PCV. Does it have milky white stuff around it ?

also, check your intake manifold bolts. If they are loose, that could be a sucking noise interacting with a gasket to make it sound like squealing.

Also, check how hard it is to turn your accessory pulleys by hand, and jiggle your pulleys to see if the bearing is moving excessively. Check the water pump carefully.

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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post #5 of 12 (permalink) Old Jul 8th, 19, 12:08 PM
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Re: Sbc 350 engine noise

Wrong size belt on water pump and alt. Too narrow. Running bottomed out in the wp pulley.

Make sure no belt got trapped back behind the wp pulley when the old one broke. Usually that will make noise all the time though.
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post #6 of 12 (permalink) Old Jul 8th, 19, 1:26 PM
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Dan
 
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Re: Sbc 350 engine noise

my guess is that squealing has something to do with why the belt went missing in the first place.
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post #7 of 12 (permalink) Old Jul 8th, 19, 2:07 PM
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Re: Sbc 350 engine noise

Water pump might be tightening up. Spin it by hand and check for excessive resistance. The belt is running fine by appearance on the alt pulley but seems to deep on the water pump pulley. Where does it ride on the harmonic balancer pulley? If it looks good might be time to source a new waterpump pulley. Preferably not a chromed ChiCom model.

Belt appears to be adjusted tight enough.

Is your battery charged? Low battery can put extra resistance on the belt causing slipping.
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post #8 of 12 (permalink) Old Jul 8th, 19, 4:19 PM
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Eric
 
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Re: Sbc 350 engine noise

IMHO the power steering belt needs to go around the water pump also.

Your just jealous because you can't hear the voices!

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post #9 of 12 (permalink) Old Jul 8th, 19, 5:11 PM
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Re: Sbc 350 engine noise

Quote:
Originally Posted by oldcutlass View Post
IMHO the power steering belt needs to go around the water pump also.
I can only speak from a 70 standpoint as it's all I have proof of, the aim p 159 & p473 and my car here. The alt/water pump/crank pulley is on one belt. The power steering belt has its own belt connected solely to the crank pulley. An a/c car would have a double pulley on the power steering and an addition belt from the a/c, power steering, crank pulley. All V8 options in 70 ran a single pulley water pump with a single belt shared with the alt. Other years or models may differ.

Chevalier, what model and year is your car? Do your belts appear to be aligned and the belts running true in the grooves? I couldn't pick it out in the video.
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post #10 of 12 (permalink) Old Jul 8th, 19, 5:41 PM
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Al
 
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Re: Sbc 350 engine noise

If you want to find the noise, get a 3-4 foot piece of pvc pipe and hold it to your ear. Have someone rev the engine and listen through the pipe for the noise as you move it around. Be careful not to get sucked in to moving parts. It sounds like the belt to me, but you never really know through a video.
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post #11 of 12 (permalink) Old Jul 8th, 19, 8:18 PM Thread Starter
 
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Hey guys thank you everyone for the help, I feel like a idiot and should prob get my hearing checked out cause I could of sworn it was an internal noise. I took the belt off and hand turned the alternator and it seemed good, put the belt back on and ran it till it warmed up and and then the noise came back. Took the belt back off and turn again by hand and sure as **** it was binding up so took it off and took off the pulley and fan blade and there was serious bearing movement. So replaced the alternator and just had it up to temp again and no noise thank god! But as far as the belts alignment it doesn’t look correct I’ll upload a photo so you can see what I’m saying. but honestly not worried cause planning on converting to serpentine belt set up I’m just so relieved my motor is fine haha.

Car is a 1971 chevelle with just a 350 small block and no AC. So have the one v-belt around alt, water pump, crank. And the other belt just around the crank and power steering pump. Everything looks straight and properly aligned except the alternator.
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post #12 of 12 (permalink) Old Jul 8th, 19, 8:47 PM
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Dan
 
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^^^* i used to think the same about the alt on my Monte Carlo....Visually looked way off. A straight edge proved i needed glasses.
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