Thread: 327 Chevy v-8 knock/tapping noise

Tweet

Over the past 3-4 months my 327 v8 in my 64' belair has developed a knocking/tapping noise, about a week ago we took the car over to a friends/mechanics garage and took the valve covers off and none of the lifters were broken so we adjusted all the lifters, added a little bit of oil was a little low, but it still has the knock

It will mostly do it at lower rpm's because I haven't hear it at higher rpm's and it will mostly never do it at idle, idk if it may be not heavy enough oil or something else and the motor has 350 heads and a mild cam if that helps...and I still drive this car every day back an forth to work

Would appreciate a quick response because I have a guy who is wanting to trade for my car in the next couple days

If this description isn't clear enough and you have more questions just let me know....

Thanks Alot Guys,
Robert

Robert-You do understand how hard that is over the net.I don't have audio,but maybe some of the other guys do and if you could post that,it might help.

You know you have TWO post with the same question???

put your stethoscope on the timing chain cover and listen....

mike in tucson

Could be carbon build up. Run some cleaner thru it.

Still think it could be flex plate,

Originally Posted by cffisher

You know you have TWO post with the same question???

Maybe that means it knocks twice as much as it used to????

Gonna run a can of sea foam thru it tommorow and gonna take it to a friends place to lift it up so we can take a better look underneath


Thanks guys!!

Wish me the best of luck on a quick diagnosis and hopefully an easy fix lol

Robert,
Seafoam can't hurt, and it's great for cleaning out deposits, especially if you let a vacuum hose (like your brake booster line) suck it straight out of the can into the intake, shut down to let it soak a while and then start it up again to purge. But I can't see how it's going to cure the knock you've described. What's strange to me is that while you say you hear it at lower rpm's, it is not there at idle? That's kind of strange for an internal knock, at least in my mind. I like the idea of getting it in the rpm range where the knock is worst, having someone hold it steady at that rpm, and then use a big screwdriver, metal rod, or even a hardwood dowel as a stethoscope, moving one end around on different parts of the engine (stay clear of belts & fan) with an ear on the other end, trying to pinpoint where the noise is coming from. If it is indeed only happening in a rpm band above idle, but below say 2000rpm then Charlie may have nailed it with a cracked flex plate, or robot's timing chain slap? Whatever, let us know what you find!!

Since I have had literally no time to take a better look at my car due to work I wa able to take a quick video of it do yall can hopefully hear it. So this video is from my Facebook so I hope y'all can view it....I still drive this everyday.

https://fbcdn-video-a.akamaihd.net/c...e0fc3e528a4b86

I think charlie is right it's a cracked flex plate ....ted

You might want to get it on a lift and using a small recording device with an external microphone (or the methods mentioned above) (you can get an automotive stehiscope (sp) at Harbor Freight or somewhere else) and try to diagnose the correct location of the noise before taking anything apart. Just be very carefull around the spinning torque converter of course.

I would also check the torque converter for loose bolts. You are probably going to have to remove the trans to check the flex plate properly.


EDIT:
Ok how do you guys get a space between what you type and the black line at the bottom of your posts?

.

Originally Posted by Bug

EDIT:
Ok how do you guys get a space between what you type and the black line at the bottom of your posts?

What black line? The one above the quote? I usually press the enter key a couple times.

under edit, when it's a post (on my screen) it's a white line!

And pressing enter doesn't change the distance under the final sentence..

again under edit, testing if you press enter a couple times the add a character like the period does it stay with that space?


..

A piston pin will knock at mid rpm's and not at idle.I had one like that.

Originally Posted by 34_40

What black line? The one above the quote? I usually press the enter key a couple times.

under edit, when it's a post (on my screen) it's a white line!

And pressing enter doesn't change the distance under the final sentence..



again under edit, testing if you press enter a couple times the add a character like the period does it stay with that space?


..

I press enter a half a dozen times and still no change. If I put in a "." then it leaves a space because there still is something there on the last line.