The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 What's going wrong inside my 350?

1project2many · 01-01-2019, 11:14 PM

That's an interesting sound. Does it do it as soon as the engine is started? Is it louder toward the front or rear of the engine? Can you hear it during cranking if the coil is disabled? Is cranking speed normal?

It sounds like a bearing and it could be on the crank. If a rod bearing has spun slightly and is wedged against the crank the oil hole from crank to bearing can become restricted which keeps the oil pressure from dropping.

It's also possible a timing cover is touching the balancer or that there's something wedged against the oil pump drive but those sounds are usually different. The balancer noise is a bit tinnier and the oil pump drive isn't as loud. But the problem with a video is it's hard to get relative sound levels.

But I have heard a strange squealing before that can sound very bad but is actually easy to cure. If the PCV valve is doing its job and drawing air out of the crankcase but there is no way for air to enter the crankcase, air will begin to flow past the main seals. It is very loud. This happened in one case because a set of cheap chrome valve covers came with grommets that weren't actually opened so the breather could not pass air into the engine. In another case an individual installed a PCV vavle in each valve cover not knowing one needed to be vented. In both cases the noise started several seconds after engine start. If you suspect this may be a problem, the easiest check is to ensure the crankcase is vented, possibly by pulling the PCV valve while the engine is running.

Also, mild cam plus 3000 stall converter??? That may not give you the performance you want. But it may not be an issue...

01-01-2019, 11:14 PM	#8
1project2many Registered User Join Date: Mar 2012 Location: Lakes Region NH Posts: 3,158	Re: What's going wrong inside my 350? That's an interesting sound. Does it do it as soon as the engine is started? Is it louder toward the front or rear of the engine? Can you hear it during cranking if the coil is disabled? Is cranking speed normal? It sounds like a bearing and it could be on the crank. If a rod bearing has spun slightly and is wedged against the crank the oil hole from crank to bearing can become restricted which keeps the oil pressure from dropping. It's also possible a timing cover is touching the balancer or that there's something wedged against the oil pump drive but those sounds are usually different. The balancer noise is a bit tinnier and the oil pump drive isn't as loud. But the problem with a video is it's hard to get relative sound levels. But I have heard a strange squealing before that can sound very bad but is actually easy to cure. If the PCV valve is doing its job and drawing air out of the crankcase but there is no way for air to enter the crankcase, air will begin to flow past the main seals. It is very loud. This happened in one case because a set of cheap chrome valve covers came with grommets that weren't actually opened so the breather could not pass air into the engine. In another case an individual installed a PCV vavle in each valve cover not knowing one needed to be vented. In both cases the noise started several seconds after engine start. If you suspect this may be a problem, the easiest check is to ensure the crankcase is vented, possibly by pulling the PCV valve while the engine is running. Also, mild cam plus 3000 stall converter??? That may not give you the performance you want. But it may not be an issue...