Knock, knock, knock sound

i would pull the pan , not run it more . check exhaust for leak . could a piston be hitting a valve or the head ? .............. good luck .
 
I have only 100 miles on the engine since I rebuilt her.
Click to expand...

What exactly was done to rebuild the engine? The term "rebuilt" means different things to different people.
 
It is not a main. It sounds like it is missing also. A main would knock worse under load. You sure it does not change when you short it out. To me it sounds like a broken piston. But it is real hard to tell with out being there.

To me when some one says rebuilt I get real worried.
 
I recently developed a knock on the 31 AA, fearing the center main was gone I started with the simple first. Pulled the belt still knocked. Checked with a stethoscope and found the noise throbbing in around the cam gear. Pulled the side cover a found the cam gear real loose, like a half inch wobble. This engine still ran!? Pulled the front cover and inspected the plunger and spring, all good there. Took the cam nut off the last four threads and washed the nut and cam off with Brake clean. Air dried them up and applied a little Blue Loc-tite. Screwed it back on and tightened it up. I hand cranked it over to find no missing or ruined teeth, so I just buttoned her up and took it for a lap. She's happy again!
 
machineman64 said:
Another possibility could be a collapsed spring behind the cam plunger allowing the cam to move back and forth. This happened to me on a 29 model a I owned about 62 years ago.
Click to expand...

This also happened to me once but the knock came and went with changes in engine speed. It would also change timing as the cam moved back and forth in the block. I had to retime the car every few miles to keep it running and later discovered the broken cam plunger spring as the culprit.
 
SINCE IT WAS JUST REBUILT.


I wonder if the Dipper tray pan has popped loose and the rods are striking it!
MAYBE dipper tray was loose and not snapped all of the way into the grooves.

At least it sounds that way to me!!
 
Last edited:
Glen in Hillman MI said:
With engine turn off pry gently on the crank pulley to see if moves back and forth
Click to expand...

Well, I removed inspection cover for the timing gear and she still looks good for an original gear. Not loose at all. So then I used a bar to see if the crank moved back and forth and yup she does. About 1/8 of an inch. Video below.

https://vimeo.com/222254828

I guess Tomorrow the pan comes off as Im fearing the worst.
As for rebuild. I was the one who basically took it all apart, cleaned everything and but her back together years ago in 2003.

If it's time to do the ol girl right, it's time is now. Anyone want to come help?

Michael
 
Our Vicky developed a similar sound. It is. Model A Engine with a Miller Overhead Valve Head.
The sound was more of a clicking sound, not a deep thud like a rod or main. I first thought it was the rockers not properly adjusted, that didn't work. Removed fan belt, no change, shorted out spark plugs, no change in the sound. I also used a stethoscope, but couldn't locate the source. It did seem noisier under the car, pan area. Lighter metal of the pan might have amplified the noise.

I removed the engine, checking everything I could think of along the way.

I found the problem to be a lose Timing Gear. The nut was backed off a couple of threads, and there was significant movement in all directions, as well as very worn. It was a fiber gear, being replaced with an aluminum gear.

It is not back together yet, doing some other things while it is apart, but I'm sure this was the problem.
 
Tom Wesenberg said:
Hopefully all the rod scoops have the opening facing the camshaft.

Guess we'll learn more tomorrow.
Click to expand...

Hi Tom, all scoops are facing the cam.

Well I think I found the issue.

20170620_175212_zpsovserfof.jpg


20170620_175312_zpsvdcgyoh9.jpg
 
I'm wondering how that engine ran with 2+ teeth missing.

Is that the clicking sound heard in the video?

Is the broken cam gear "the issue" or is it a result of the issue?
 
With a all of fiber inside oil pan ... Do Not forget to clean out the oil pump filter screen inside the "cover" of oil pump!
 
Dick Steinkamp said:
I'm wondering how that engine ran with 2+ teeth missing.

Is that the clicking sound heard in the video?

Is the broken cam gear "the issue" or is it a result of the issue?
Click to expand...

Hi Dick, yes this was the thumping sound. I am not 100% sure what caused this. Can anyone shed light if excessive end play on the crankshaft would cause failure or was it just the gears time to go ?

Michael
 
You must log in or register to reply here.
Back
Top