Knock, knock, knock sound

[ford-m]

On Friday afternoon I drove the Roadster a mile into town and she preformed flawlessly. When I was coming home I stopped at a set of lights and suddenly this now sound emerged. No difference in power or response, just a noticible knocking noise. When reving engine it also increases
Went away for weekend and now home troubleshooting the issue.
Took belt off so it's not fan or alternator.
Sound is louder on the exhaust side.

I have only 100 miles on the engine since I rebuilt her.
What do you thinks it is and where do I start? The video is below.

http://http://vid1291.photobucket.com/albums/b558/Ford-m/20170618_140851_zpst12kgeu2.mp4

[JDupuis]

Ford-m, is it possible that it may be an exhaust leak? I did not watch the video as it had too many pop-ups telling me I am a winner. So I didn't see video, sorry. Jeff

[ford-m]

Hi Jeff,
Definitely not exhaust.
Try this video.

http://vid1291.photobucket.com/album...ps40btt7fp.mp4

[ford-m]

Here is a much better video.
I'm thinking it's time for a new can gear perhaps ?

https://vimeo.com/222119113

[DJ S]

Oh man, that sounds like a bad bearing.

[JDupuis]

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Sorry Ford-m, sounds bad. Ground out one spark plug at a time. This might narrow down where the noise is coming from.

[Marshall V. Daut]

Yes, short out each spark plug in turn until you find the offending cylinder. It sounds like a rod bearing to me. If it stops when that cylinder is shorted out, odds are it's the rod Babbitt gone South.
Marshall

[stewwolfe]

That sounds deep, like a main bearing, but not being there in person, I could be wrong. I would drop the pan and check clearances, just to be sure.

[ford-m]

Originally Posted by JDupuis

Sorry Ford-m, sounds bad. Ground out one spark plug at a time. This might narrow down where the noise is coming from.

Hi Jeff,
Just tried grounding each plug with NO difference in sound. Knock was still there. Might be time to drop the pan ?
Regards,
Michael

[Marshall V. Daut]

Well, that's GOOD news! That means it may not be a bearing after all. Before you drop the oil pan, pull off the side timing gear cover and pry behind the timing gear in a couple places. If the timing gear nut has worked loose or some gear teeth have stripped, you should feel a wobble. That would be the best of all worlds if all you need to do is change the timing gear. Not fun while still in the car, but a heck of a lot better than dealing with bad bearings!
Marshall

[DJ S]

Originally Posted by ford-m

Hi Jeff,
Just tried grounding each plug with NO difference in sound. Knock was still there. Might be time to drop the pan ?
Regards,
Michael

Yup, drop the pan. It's most likely the center main bearing as they're usually the first to go.

[Marshall V. Daut]

Does the sound change at full retard and then at full advance? If the sound lessens at full retard (but doesn't go completely away), "DJ S" may be right about the center main. The knock sounded higher pitched to me in your video than a main bearing, but if a main bearing is going to go, it's usually the center one first.
Marshall

[jg61hawk]

I'm probably way off BUT a video is hard to say exactly what...but I had what I thought was a rod knock and it was only a head gasket. Does the sound change with the timing changing and also spray soap around the head and see if you see bubbles. What do you have lose...go simple first.

[Ian in Mississauga]

Michael, 3 summers ago I had a freshly rebuilt motor develop a knock after less than 100 mi. The rebuilder took care of it promptly. Turned out to be a center main that had a partially blocked oil supply line.
Good luck, Ian

[Ed H.]

Take a long screw driver to see if you can isolate the noise. If it is the timing gear you will hear it through the screw driver shaft. Or if you have a mechanic's stethoscope that will do the same.

[TerryH]

I had a knocking sound in my engine, and it turned out to be a bad fiber timing gear. Prior to that, several Model A friend's were not able to diagnose it accurately. Had a new gear installed and all is better now!

[Big hammer]

Check for oil flow, thats a nasty noise!

[Tom Wesenberg]

Originally Posted by Marshall V. Daut

Does the sound change at full retard and then at full advance? If the sound lessens at full retard (but doesn't go completely away), "DJ S" may be right about the center main. The knock sounded higher pitched to me in your video than a main bearing, but if a main bearing is going to go, it's usually the center one first.
Marshall

X2, that was my thoughts exactly.

It'll be interesting to find out what it is.

[Dick Steinkamp]

Super hard to diagnose from a video, but to me it sounds more like something from the valve train than a main or rod bearing. Broken valve spring, valve seat insert came loose, adjustable lifter loosened up?

[machineman64]

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.

[BILL WILLIAMSON]

"POSSIBLY" loose flywheel bolts??? Pry on flywheel teeth & see if flywheel rotates back & forth about 1/8 Inch.
Bill Loose

[V4F]

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 .

[Glen in Hillman MI]

With engine turn off pry gently on the crank pulley to see if moves back and forth

[Ray in La Mesa]

Please let us know what you find.

[katy]

I have only 100 miles on the engine since I rebuilt her.

What exactly was done to rebuild the engine? The term "rebuilt" means different things to different people.

[George Miller]

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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.

[Farrell In Vancouver]

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!

[ursus]

Originally Posted by machineman64

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.

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.

[Benson]

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!!

[Kohnke Rebabbitting]

Sounds like first, or second rod to me.

Herm.

[Kahuna]

I'm with the loose flywheel crowd

[ford-m]

Originally Posted by Glen in Hillman MI

With engine turn off pry gently on the crank pulley to see if moves back and forth

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

[Willie Krash]

The first video hurts to listen too.

[Tom Wesenberg]

Hopefully all the rod scoops have the opening facing the camshaft.

Guess we'll learn more tomorrow.

[BILL WILLIAMSON]

NOTE: A Model A piston can NOT hit a VALVE!
Bill Clearance

[Vicky]

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.

[ford-m]

Originally Posted by Tom Wesenberg

Hopefully all the rod scoops have the opening facing the camshaft.

Guess we'll learn more tomorrow.

Hi Tom, all scoops are facing the cam.

Well I think I found the issue.

[Dick Steinkamp]

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?

[Benson]

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!

[ford-m]

Originally Posted by Dick Steinkamp

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?

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

[1930 coupe]

I have seen people put 50 or 60 year old used fiber gears in a engine because the gear looked good. Most of these old used gears only lasted for 100 to 300 miles before the teeth broke off. My theory is that when the gear soaks in oil for 50 or 60 years it gets soft and the teeth break off when you try to run it.

[Tom Wesenberg]

My 31 also had a timing gear that looked like that when I bought the car. It had 1957 plates on the car, and I don't know if the car was parked for that reason, or If the engine had a stuck valve that tore the teeth off when I tried to start it. Anyway I installed a new gear, and the engine runs like a Swiss watch.

Your gear has the aluminum center, so it needs to be changed anyway before the center works loose.

I see signs of rust inside your engine, so be sure to polish it all off the crank gear before installing a new cam gear.

[Ed Saniewski]

Could the main crank moving back and forth that much be the cause the timing gear was damaged?

[Big hammer]

What may have caused the teeth to break off, some people used a rag between the gears to torqe the cam nut!

[BILL WILLIAMSON]

Originally Posted by Big hammer

What may have caused the teeth to break off, some people used a rag between the gears to torqe the cam nut!

Dave had a NEW respect for his WIFE, after she held the engine with the CRANK, while he tightened the CAM nut to 105 Ft. Lbs (DON'T CROSS THAT WOMAN!!!)
Bill W.

[Tom Wesenberg]

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Good time to install an aluminum gear.

[denniskliesen]

Originally Posted by ford-m

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

Ha! When I got my A home after it had sat in a carport since 1980 the first thing I did was drain the oil and the cam gear teeth. Yeah all the teeth were broke of the cam gear and it was still in time with the crank gear. While rebuilding it got an aluminum gear.

[katy]

Seeing as you're going to be replacing the cam gear, unless the crankshaft gear is pristine I would suggest that you replace it at the same time. It's always best to replace gears as a set.

[Tom Wesenberg]

Originally Posted by katy

Seeing as you're going to be replacing the cam gear, unless the crankshaft gear is pristine I would suggest that you replace it at the same time. It's always best to replace gears as a set.

I would likely do the same thing if the crank was out of the engine, but since the gear is so hard to remove, I sanded the rust on my crank gear. I used a rag under the gear to catch any rust or grit.
The cam gear had a crack in one tooth, so it needed to be replaced.

You can also see all the wear on the aluminum sleeve of the two piece pulley. I replaced it with an original one piece pulley I had.

[Fred K-OR]

Ford-M, did you get your rig fixed? Have you eliminated the knock with a new timing gear? Just wondering in that I am in the process of thinking I have the same problem but have not torn anything apart yet.