Mystery Engine Noise - 65 L79

[Donald T.]

Okay, I'm hoping the brain trust can help me out with this one. I have an engine rattle/vibration that I can't seem to track down. Sounds like it is coming from the valve train, but from under the car sounds like it might be from the bell housing area. Touching the clutch changes the pitch slightly, so I replaced the throw out bearing - no effect.

I have also adjusted the lifters and shimmed the starter with no effect. I'm out of ideas. I uploaded a video clip with audio at the link below. Any suggestions?

http://www.youtube.com/watch?v=-8cj60UruZ4

[Joe C.]

Re: Mystery Engine Noise - 65 L79

Sounds "tinny".
Did you do anything to the car before then noise started?
Could it be the bellhousing inspection cover? Could it be one of your pulleys? How about the timing cover?

[Donald T.]

Re: Mystery Engine Noise - 65 L79

Sounds "tinny".
Did you do anything to the car before then noise started?
Could it be the bellhousing inspection cover? Could it be one of your pulleys? How about the timing cover?

Joe,

The engine was rebuilt before I owned it, and the noise has always been there. It is just more noticeable since I replaced the side pipes with standard exhaust. I have replaced the pulleys and the timing cover. I never considered the inspection cover, so I have not checked that yet.

[Stuart F.]

Re: Mystery Engine Noise - 65 L79

Don;

For what it's worth, I listened to your video and I can state from experience it's not a broken crank. That would be an intermittent rattle like there was some loose ball bearings in the bell housing.

Stu Fox

[Joel T.]

Re: Mystery Engine Noise - 65 L79

Don;

I agree with the "tinny" sound that someone else called out... That inspection cover is certainly worth a look. If you can arrange it, get the car up in the air, running, and see what you can hear from the underside and try to pinpoint the source. Since you have recently removed your side exhaust, that would rule out the exhaust pretty much... and also explain why you are hearing it more now than before... underside exhaust being quieter overall.

When you swapped out the throw out bearing, did you make sure that all the flywheel and pressure plate bolts were in there tight? How about the pressure plate springs.... did you see if there were all in place, and none were broken or appeared to be of incorrect height??

I remember from the "old days" that loose flex plate bolts would result in pronounced "tick" with the engine running once you stepped on the gas or decelerated for that matter.....

Hope this helps...

Joel

[Joe C.]

Re: Mystery Engine Noise - 65 L79

I just listened again. Did you rev the engine once or twice in the video? If you did, then it sounds like the pitch of the noise did not change. If so, that makes it tougher for me, to come up with a culprit. Does the pitch change when you rev the engine, or is it just my tired eardrums?

Joe

[Ray G.]

Re: Mystery Engine Noise - 65 L79

Hello Donald;

Sounds to me like Joe got it right on his first response.

We joke about "put the telephone near it so I can hear it" diagnosis.

But it sounds like the technology of the day has improved to the point of actually being able to do diagnosis from a distance.

Hope this helps
Ray

[Paul J.]

Re: Mystery Engine Noise - 65 L79

Don;

That's a tough one. It certainly sounds initially like valvetrain. By "adjusting the lifters" I assume that you mean that you adjusted the valve lash at the rocker arms. That would be my first choice as to the root of the problem.

If you're convinced that it is coming from the rear of the engine, the flywheel may be touching something. I know you shimmed the starter, but how does the drive gear and the casing look? I assume that this is the right starter.

Finally, the noise sounds remarkably like a stretched timing chain. However, you said that it comes more from the rear of the engine.

I'm going to have to do a little research on whether or not it could be the distributor.

My assistant mechanic just walked in. I'll have him listen to the video.

Good luck with this. I don't blame you for trying to chase it down. It would drive me nuts.

Paul

[Paul J.]

Re: Mystery Engine Noise - 65 L79

Don,

The only other thinkg that we can come up with is that you could have a cracked flywheel. This is very possible if the starter was not shimmed correctly.

Paul

[Donald T.]

Mystery Solved!

Well, looks like Joe nailed it. I removed the inspection cover and started the car without the cover. The offending noise was gone. You can see that the flywheel was hitting the inspection cover at the bottom of the pic. I'll just order a replacement. Surprising that a little rub like that could make so much racket!

Thanks!

[Donald T.]

Re: Mystery Engine Noise - 65 L79

Just an update. I ordered a new inspection cover and installed it today. No more noise! Now the engine purrs like a kitten... er, uh, maybe maybe more like a mouse.

Thanks to Joe and the others that pointed me in the right direction. Thanks!

[Stuart F.]

Re: Mystery Engine Noise - 65 L79

Donald;

I like your choice of words. Would you say it sounded more like a "Rat" before (apologies to the BB guys)?

Seriously, I'm glad to hear you have your problem solved. It's a good feeling.

This old man had to drain oil out of my engine this morning. I over filled it as I'm not used to using gallon jugs and filling the filter. I am now. Going on a jaunt later this afternoon to our cruise-in at Old Town. Requires about 20+ minutes on the Greenway @ 65 mph+ and I thought it unwise to run with a half quart over.

Stu Fox

[Joe L.]

Re: Mystery Engine Noise - 65 L79

Just an update. I ordered a new inspection cover and installed it today. No more noise! Now the engine purrs like a kitten... er, uh, maybe maybe more like a mouse.

Thanks to Joe and the others that pointed me in the right direction. Thanks!

Donald-----


You might not have actually needed a new cover. Note that the cover has small "ears" at the ends of the semi-circular area. These are designed to clip under the rear oil pan seal lip. Sometimes, when folks install these covers they fail to get the "ears" behind the oil pan lip. When this occurs, the ears actually "work to create the problem that they're designed to prevent" and help distort the cover inwards so that it contacts the flywheel.

By the way, I don't think that the original 1965 inspection cover had the "ears" but later SERVICE replacements definitely did, so I think your existing cover is a previous replacement.

The problem of the inspection cover contacting the flywheel is VERY common, especially on cars not equipped with the "eared" covers.

[Donald T.]

Re: Mystery Engine Noise - 65 L79

Donald-----


You might not have actually needed a new cover. Note that the cover has small "ears" at the ends of the semi-circular area. These are designed to clip under the rear oil pan seal lip. Sometimes, when folks install these covers they fail to get the "ears" behind the oil pan lip. When this occurs, the ears actually "work to create the problem that they're designed to prevent" and help distort the cover inwards so that it contacts the flywheel.

By the way, I don't think that the original 1965 inspection cover had the "ears" but later SERVICE replacements definitely did, so I think your existing cover is a previous replacement.

The problem of the inspection cover contacting the flywheel is VERY common, especially on cars not equipped with the "eared" covers.

Thanks Joe. You are correct as usual. I noticed that one of the ears was bent as you suspected. The old inspection cover had a couple of cracks in the metal from contacting the flywheel, so I thought it best just to replace it. Good to know it was just a service replacement, so I'll just toss it.

[Patrick H.]

Re: Mystery Engine Noise - 65 L79

Did you paint the new cover orange so that it now also appears "correct?"