Stumped on this one. 1960 original straight 6 223 with original exhaust, carb, intake, everything...

When I drive my truck there is an almost rhythmic clank every few seconds.

It doesn't happen at 50-55 MPH and up. It doesn't happen at low RPM's. Mainly it occurs in 2nd or 3rd gear at 35-45 mph.

And I cannot duplicate it in my driveway by idling and revving engine. Engine is smooth as can be.

If I open the hood and try to figure it out.. I keep going to the exhaust valve on my headers because I can open it and let it go, and it makes the "clank" I am hearing but it isn't as loud as it is in the cab. The exhaust manifold is pretty rusted but this valve does open and close easy.

If I lightly tap my clutch... the noise goes away. Inspecting the clutch nothing appears loose. The only thing that seems odd though is the lever/plate that pushes the clutch back when you press the pedal. There is a bolt on one side (the engine side) but not on the back side. The plate thing has some play but it is pressed snug against that bolt. It seems odd to me though there is no bolt on the other side and therefore I wonder when I am driving to speed if this is where the clank is too.

Any thoughts?

 

Watch your oil pressure gauge (if it has one?) as you are running at steady speed, 1500 RPM or so, with no load. Then give it some gas. If the oil pressure drops, but comes back up when you let up on the gas, I'd bet you have a bad thrust bearing (I think it's the center main bearing), and the rod bearings are likely getting starved. It won't be long til one of them lets go, don't ask how I know.

You can wire the exhaust flapper open to eliminate that as a cause.

 

Those sound like classic syptoms of a dying u-joint to me. It might not hurt to drop the driveshaft and check them out.

 

If you can get a long screw driver and place it in various places on the motor, put your ear to it you will be able to hear all the sounds in your motor. You can also operate the throttle quite easily. Just be REAL DAMN CAREFUL with your hands and clothes around the pulleys and belts, your hair too if you still have any. This will either confirm or tell you to look elsewere for the problem.

 

Oil pressure is fine. I was losing pressure but I had some real bad gaskets that I replaced.

I'll check u-joint.

I'm going force open exhaust valve

 

Okay... albuqf1... Can't rule that out.

Opened exhaust valve, still makes noise.

There is a mile long hill out here so drove up at 40mph. If I rest my toe on the clutch there is no noise. I left off... Noise starts. Every 3 -5 even 10 seconds. clank!!!

 

by saying it goes away with your toe on the clutch pedal, that sounds like a throwout bearing/pressure plate item possibly. or is there something loose somewhere in the pedal assembly maybe?

 

That is what I am thinking.

 

So you follow the line to the clutch. You have the lever that pushes back. There is a threaded nut up tight to that metal that pushes the pressure plate. On the other side there is no nut and it wiggled in that space. Is that supposed to be like that. The spring pushes out and it comes back fine.

 

i think what you are talking about is the arm for the throwout bearing. it goes into the bell housing? and the bolt you are talking abolt is the pivot point for that arm. when you push the clutch,clutch rod pushes on the arm against the ball ended bolt. which, in turn, the arm goes opposite direction to push the bearing against the pressure plate arms, which releases the clutch disc between the pressure plate and the flywheel.

Anyone got a pic of that?

 

its possible that the ball ended stud, pivot, whatever ya want to call it, could be worn or the arm where the two meet. I don't think it should be very loose but if you ride with your toe on the clutch pedal, you will prematurely wear out the throwout bearing. I learned that the hard way when i was a kid! Dad made me replace one! and you learn!

 

No... I wouldn't ride it. . I am about fixing stuff.

This is my "hauling dirt and stuff from Lowe's" truck. Funny... No noise at highway speed. See if I can snap a pic shortly.

 

Most of us aren't familiar with the 57-on hydraulic system for the clutch, can you take a picture of the clutch fork where you think a bolt is missing?

 

Hydraulic clutch on a '57 ??? yeah I didn't know that! i assumed it would be all manual stuff! My '66 bronco was manual...and Ross, thanks for the correct part name! i couldnt spit it out! "clutch FORK"

 

Throw out bearing or bad finger on preasure plate?