Identify engine sound?

[Roald P.]

I started my 68 vette (standard 300 hp 327cui) today to make it ready for spring, but after a few minutes of warmup, the engine started to make a noise which seems to follows the rpm's.

Can any of you identify where the sound originates from? The sound is most audible at the drivers side valve cover, but sounds like it coming from within the engine

http://www.youtube.com/watch?v=9NgAJqss5Qw

regards,

Roald

[Steven B.]

Re: Identify engine sound?

I would first pull the cover and check lifters before going deeper. If loose or not pumping you can hear, see or feel it.

[Roald P.]

Re: Identify engine sound?

I would first pull the cover and check lifters before going deeper. If loose or not pumping you can hear, see or feel it.

I've already done that and did run the engine on the starter with the cover off. Everything seemed normal. I was not able to hear the sound when running the engine on the starter. I'm also dropping the oilpan anyway to correct an oil leak.

[Steven B.]

Re: Identify engine sound?

I've already done that and did run the engine on the starter with the cover off. Everything seemed normal. I was not able to hear the sound when running the engine on the starter. I'm also dropping the oilpan anyway to correct an oil leak.

Sounds like you covered that. If no problem with the valve train, including pushrods when you drop the pan check the rods and caps. From what I could hear it sounded pretty loud.

[Roald P.]

Re: Identify engine sound?

Sounds like you covered that. If no problem with the valve train, including pushrods when you drop the pan check the rods and caps. From what I could hear it sounded pretty loud.

It is clearly audible, but not that loud. I put the microfone directly to the engine which amplifies it a bit. What puzzles me is that there was nothing when I put the car away 3 months ago!

[Patrick H.]

Re: Identify engine sound?

I've heard something "similar" with a loose spark plug.

Patrick

[Roald P.]

Re: Identify engine sound?

I've heard something "similar" with a loose spark plug.

Patrick

Thanks, didnt think about that one.

[Ted S.]

Re: Identify engine sound?

Did you check for an exhaust leak at the manifolds?

[Ted S.]

Re: Identify engine sound?

Also if you rev and let off does it go away on the rev and come back as you let off?

[Richard M.]

Re: Identify engine sound?

Check the bolts holding the drive pulley on the harmonic balancer.

Our '63 327-300 had a very similar noise. It sounded like it was internal to the engine. All 3 bolts were loose.

Rich

[Roald P.]

Re: Identify engine sound?

Did you check for an exhaust leak at the manifolds?

Yep, didnt seem like the sound was coming from there.

Also if you rev and let off does it go away on the rev and come back as you let off?

Its a bit difficult to hear, but I think the sound follows the RPM's up until a point where I cant hear it anymore and comes back when I let off the gas. The fan makes alot of noise when I rev it so Im not 100% sure.

[Roald P.]

Re: Identify engine sound?

Check the bolts holding the drive pulley on the harmonic balancer.

Our '63 327-300 had a very similar noise. It sounded like it was internal to the engine. All 3 bolts were loose.

Rich

Will check that too, but it sounds like the sound is coming from the upper part of the engine, just below the carb. The noise is not that clear when I stand below the oil pan with the engine running.

[Wayne W.]

Re: Identify engine sound?

Most likely a lifter. Common when one has set for a while.

[Jim W.]

Re: Identify engine sound?

Check the bolts holding the drive pulley on the harmonic balancer.

Our '63 327-300 had a very similar noise. It sounded like it was internal to the engine. All 3 bolts were loose.

Rich

I also had a similar noise a few weeks ago on my 64 327/300 that fluctuated with RPM, especially when goosed. Checked everything with a stethoscope and concluded it was coming from the fan area (the only spot I couldn't place it on). Took the belt off and started it,no noise. Then realized the pulley bolt was loose. All better now. I would check that first for a simple fix or to rule it out before pulling my hair out.

[Richard T.]

Re: Identify engine sound?

Sometimes noise will show up after a few months of down time. You said you warmed your engine up; I assume to normal operating temp. Your therm clutch on your fan could be the cause or one or more of your fan belts. I am assuming you checked lose belts, bolts, plugs etc. Try some belt dressing to see if the noise goes away. If not you will have to scope your engine to find the problem; sticking valve, lifter etc. If you are running racing motor oil drain it and go with detergent. My 67 motor made noise when I put in racing oil. You can also remove the belts and restart, to quick check the front of the engine. Hope it is a easy fix.