Engine Noise - Base 350 (1969 Vette)

[E. Jacobson]

I seem to be having a loud knocking/clicking sound coming from my engine when I accelerate. The sound appears to be coming from beneath the valve covers on the passenger side of the car. At idle, you can not hear the noise. However, as te RPMs increase, the knocking/clicking gets worse. The noise is similar to what you would hear if you were to take a hammer and tap on metal.

Before I start to troubleshoot the problem, I was wondering if anyone could give me some ideas as to what might be causing the noise.

Thanks in advance for your help.

EJ

[Roy B.]

Re: Engine Noise - Base 350 (1969 Vette)

First thing I would try is to pull off one at a time, a plug wire and see if it stops or decreases to locate which cylinder is knocking, if it works you could have a collapse bad piston, or wrist pin.
If it don't change may be a lifter, rocker or piston rod. Hopefully it's CARBON on top of the piston and if so running water down the Carb as you run the engine at about 2K it will remove it.

[E. Jacobson]

Re: Engine Noise - Base 350 (1969 Vette)

Good information. I am also having an issue with my carberator. It seems to be running rich. I replaced the sparkplugs several weeks back and when I pulled one of them last night, it was pitch black. Lots of carbon build up. Hopefully, the problem is carbon on the top fo the piston.

When you say run water down the carb. I assume that you mean to run water down the throat of the carberator while it is running? Is that correct?

Thanks,

EJ

[John Chesher]

Re: Engine Noise - Base 350 (1969 Vette)

I'm sure Roy will respond, but I thought I would in the mean time. The procedure as previously given to me (and I used on my car) is to have someone hold the throttle at 2000 RPM. Then pour a small stream of water into the carb throat, as much as you can pour in without causing the engine to die. It will supposedly break-up the carbon. If carbon is present and breaking up, I think you get a black smoke out the tail pipes. You continue running water through the carb until the smoke clears to more of a clear/white steam look.

[William V.]

[Mike McKown]

The water will work

I'd get an empty dishwashing liquid bottle with the squirt top on it. You can get a little or a lot by how hard you squeeze. You don't want to use a garden hose!

I haven't seen this happen much since leaded gas went away unless there was a mechanical deficiency with the engine.

If carbon buil-up isn't the problem, I'd pull the pan and start checking rod bearings. Hard to say without listening to yoor engine.

[E. Jacobson]

Re: The water will work

In your opinion, would the carberator running too rich cause carbon build up on the pistons?

Thanks,

EJ

[Joe L.]

Re: Engine Noise - Base 350 (1969 Vette)

EJ------

I think that the most likely cause is a bad valve lifter or bad rocker arm. It could be more serious than that, but I think these are the things I'd check first.

[Roy B.]

Re: The water will work

In the real oooold days we used trans fluid which gave out a lot of white smoke and worked much faster breaking up the Carbon. And yes you can still get carbon build up, it's also great to free up the oil rings being stuck.But only old farts know any of this stuff and many other solutions and will do it.

[Mike McKown]

Don't forget!

Marvel Mystery oil will do the same on the rings. I'm not as old as you but I'm old enough!

[John O.]

Re: Engine Noise - Base 350 (1969 Vette)

Hi EJ
One thing you may want to try is to use a auto stethoscope or long screw driver to listen to which rockerarm is making the noise.Take off valve cover and check for looseness on rocker arm.May only need adjusting or You might have a stuck lifter or plugged lifter rod keeping oil from getting to rockerarm. Just my 2 cents for you to check this.

John

[Roy B.]

Re: Don't forget!

The Mystery of the Marvel is that it's a water base oil?????????

[Christopher R.]

Re: Don't forget! - Marvel Mystery Oil

You wanna see smoke? Pour Marvel Mystery Oil in a running engine. It'll make enough smoke in a few minutes to fill a city block. Neighbor almost called the Fire Department on that one too.

[mike cobine]

Be careful to avoid hydrostatic lock

You need to be sure the water going in is turning to steam completely or you could get hydrostatic lock.

If the engine is running fast enough, you can have a very bad day if you get too much water in a cylinder. Remember there can be as little as 56 cc of room in some cylinders.

Be sure the engine is hot, and the water stream slow, controllable, and not too much.

And even if you don't get enough water for hydrostatic lock, having water in there that doesn't compress means your compression ratio gets much higher, so cylinder pressure during this can be very high.