Fresh Rebuild 427/490 - Annoying Noise....

[Keith B.]

500 miles on fresh L-36 engine rebuild including new LUK Clutch. At certain intervals upon warm-up and when engine is very warm, there is a annoying sound that I have determined up on my hoist with car running coming from the Bell housing ( clankedy,clank, clank). It sound like a bunch of loose marbles running around in the bell housing -inspection plate area. When I assisted my mechanic last summer re/re the engine install, I recall that he seemed hesitant when installing the throw-out bearing onto the clutch fork. Could it be installed incorrectly ?? The Throw-out bearing is brand new and was the best of the best machined part made in the USA.

I'm going to take off the inspection plate tomorrow and listen closely. It appears I may have to loosten the M-21, pull it back and take off the bell housing to see what is going on. The clutch fork arm, spring ,etc vibrates at time violently outside the rubber boot.

Again, any advice is sinverely appreciate.

[James H.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

I wonder if you blew your throwout bearing..

[Keith B.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

That is my worry, not keen in removing that transmission........I just have a gut feeling that the fork is not properly seated in the throwout bearing flange..........waiting for other comments.......

[James H.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

I also know that the throwout bearing has to be installed correctly on the fork. I saw an article about this and was concerned I did it wrong.. fortunately I had taken a picture of it looking into the bellhousing during assembly and I lucked out. Good luck..

[James H.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

This may help you.

[Stuart F.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

I really don't want to say this, but you may be lucky if it is just the throwout bearing. I've heard three big block engines sound that way when they broke a crankshaft. Sorry. I will say no more unless asked.

Stu Fox

[John H.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

Keith -

Do you know which bolts were used to secure the flywheel to the crankshaft? I can verify that ARP flywheel bolts are just enough longer than the GM bolts that the threaded ends can lightly contact the sheet metal lower inspection cover, much more noticeable with the clutch pedal depressed. Sounds like a tin outhouse in a hailstorm.

Diagram below shows the correct/incorrect installation of the throwout bearing to the fork; bad design - allows it to be installed wrong.

[Keith B.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

John: Thank-you for this, I searched in the archives last night and found that you had commented on the correct/incorrect TO bearing install. I sure wish I had taken a picture before we installed it.

Yes, I used ARP bolts thru the Flywheel and I will check this also.

I went out today though warmed it up, ran it moderatly hard up the freeway and nothing, invited my Dad over to have a listen and thru it up on the hoist in my garage. Ofcourse - No noise. Nothing.

It was really the loudest and most pronounced after a 30 mile trip yesterday at speeds of 60-70 miles per hour and then pulled into a Gas station and the sound is like a , "Chatter". Like balls running around loose.

When I had it running up on the hoist yesterday the "Chatter", was loudest from the Bell housing. I placed my hand on the inspection cover and no vibration or "tin-tin" sound, and the cover appears straight.

I'm going to monitor it closely, but my gut tells me it could be the ARP bolts or likely improper install of the TO bearing on the fork.

John: What is the easiest way to pull my M-21 out, if the sound re-appears. I have a hoist in my garage.

Thank-you Sir..........

[John H.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

John: What is the easiest way to pull my M-21 out, if the sound re-appears. I have a hoist in my garage.

Thank-you Sir..........

Keith -

There's no "easy" way - the step-by-step procedure is detailed in section 7 in the Chassis Service Manual.

[Wayne W.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

More likely the inspection plate is not installed correctly and hitting the flywheel.

[Duke W.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

You didn't say what speed/load conditions it occurs at, but if at idle in neutral it could be the clutch fork vibrating or "gear rattle" - a torsional vibration in the transmission.

More information might help the Board offer a better diagnosis - especially the engine speed/load conditions when you hear it, and whehter clutch in or out makes a difference.

Duke

[Keith B.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

Duke: The "chatter or vibration noise occurs intermittently and always when the car is idling in Neutral upon warm up or when the car has been run 40-50 miles down the freeway at 60-70 mile per hr speeds. Usually always occurrs with the clutch NOT engaged (out).

Yes, the clutch fork vibrates intermittently also, but not always.

Is there any fix to the clutch fork vibrating or "gear rattle" , it does not happen all the time as you can see in my last post.....

[William P.]

Re: Fresh Rebuild 427/490 - Annoying Noise....

I would think that it could be the pilot bushing in the end of the crank if it only does it idling in neutral.
Bill Purdy and don't ask how I might have found out