Knock, knock

[Fred K-OR]

No it is not "knock, knock-whose there?" but rather where does this knock come from.

My 29 coupe has a knock! It seems like it knocks every time a piston fires. It is a kind of "hard" knock. It is there at an idle, still there when the engine speeds up a bit. Has just about the same knock with the spark lever either up or down. Do not seem to notices it when running at normal driving speeds. When I short out each cylinder, it does not change the knock. I have adjustable valves. It seems to be getting louder as time goes on. I run 10-30 oil in it and now days it is around 100 degrees here in good old rainy Oregon.

Questions-could it be a valve that needs adjusting? Is it a rod bearing? Is it a main bearing? Is it the timing gear? Is it the crank going back and forth? Or what??????

Any ideas would be appreciated. Don't have much experience with this type of thing.

[TerryH]

Mine was making a rythemic slight knocking sound that several Model A friends were stumped by. A short while later we found out.....the old fiber timing gear was stripping out and finally gave up the ghost.

[Fred K-OR]

Originally Posted by TerryH

Mine was making a rythemic slight knocking sound that several Model A friends were stumped by. A short while later we found out.....the old fiber timing gear was stripping out and finally gave up the ghost.

I put a new fiber timing gear in the rig a few hundred miles ago. Could be the problem because I did not know what I was doing at the time and maybe messed it up.

[Y-Blockhead]

Originally Posted by Fred K-OR

I put a new fiber timing gear in the rig a few hundred miles ago. Could be the problem because I did not know what I was doing at the time and maybe messed it up.

Fred, easy enough to pull the cover and have a look-see...

[WHN]

Check the timing gear. Also try heavier oil. 20-50 works very well on older engines. 10-30 seems to me to be to light for 100 degrees.

Before you start tearing down the engine, try some inexpensive options.

Marvel Mystery Oil in your gas can help with valve noise. STP in oil will also help with flat tappet noise on engine with some mileage on it.

At this point it does sound like a timing gear. Enjoy.

[700rpm]

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Fred, put your timing pin in like you're timing the car, and turn the engine by hand. If the gear is loose you might feel a wobble. Did you torque that gear nut down tight, I mean really tight, and install that spring and plunger setup correctly in the timing gear cover?

The other suspects would be rods and mains. I hope for your sake that's not it. But it wouldn't be the end of the world. A lot of work to pull the engine, but Bill Barlow could pour new babbitt for you and have your block back to you in a few days.

I run 10-30 year round, and have for over 50 years, and have never had any adverse issues regardless of temps.

[Jacksonlll]

Dont rule out piston slap.

[1931 flamingo]

Take a LONG screwdriver, put the handle to your ear and start "probing" the block, etc. DISCONNECT (loosen) the fan belt FIRST ! ! !
You might be able to isolate the knock this way, FWIW
Paul in CT

[Fred K-OR]

Thanks guys for the ideas. When it cools down a bit around here, will have to try some of these ideas.

[Big hammer]

Shorting out number 2 and 3 at the same time, if knock goes away it's a loose center main

[Fred K-OR]

I tried this just now. Shorting out 2 & 3 makes the knock quieter but it does not go away. Thanks Big Hammer for the idea but doesn't seem to be that problem (I hope).

[CT Jack]

Seeing you changed the cam gear I would run a cam gear test. Take a 1/4" dia. wood dowel approx. 2 " long and round of one end so it looks like the timing pin used to time the distributor. Remove the timing pin and start the engine. Pay attention to the fan. Slowly insert the wood pin into the timing pin hole until it rubs against the turning timing gear. Apply a little inward force on the pin and note if the knock changes with the applied pin force. If it does this means either your timing gear nut is loose or the gear needs replacing. If you replace the gear I like to use a one piece fibre type.

[Fred K-OR]

Originally Posted by CT Jack

Seeing you changed the cam gear I would run a cam gear test. Take a 1/4" dia. wood dowel approx. 2 " long and round of one end so it looks like the timing pin used to time the distributor. Remove the timing pin and start the engine. Pay attention to the fan. Slowly insert the wood pin into the timing pin hole until it rubs against the turning timing gear. Apply a little inward force on the pin and note if the knock changes with the applied pin force. If it does this means either your timing gear nut is loose or the gear needs replacing. If you replace the gear I like to use a one piece fibre type.

Will have to try this in the A.M. It is possible that I did not get the gear nut on tight enough. If I remember, the nut was kind of messed up because someone before used a sharp thing to get it off and I could not get the wrench I bought on the nut.

[TerryH]

Fred....when my timing gear went bad, I had it replaced with an improved laminated type gear that should last much longer than the regular fiber type. For what it's worth, I had friends try and isolate the noise using long screwdrivers and other listening devices, and no one suspected the timing gear.....if your nut is bad, it is possible you did not get it fully tightened.

[CarlG]

Originally Posted by Fred K-OR

... If I remember, the nut was kind of messed up because someone before used a sharp thing to get it off and I could not get the wrench I bought on the nut.

If you buy a new nut, I would suggest getting the new style that uses a regular hex wrench to tighten it.

[WHN]

Originally Posted by Fred K-OR

Will have to try this in the A.M. It is possible that I did not get the gear nut on tight enough. If I remember, the nut was kind of messed up because someone before used a sharp thing to get it off and I could not get the wrench I bought on the nut.

Chisel was used to remove timing gear. I can't think of a Model A timing gear I have changed over the years that has not had chisel marks on it. Enjoy.

[Lona]

Some time ago, I had a similar noise we just could not isolate. Others also advised the likelyhood of a timing gear issue but all was fine when I took the cover off and inspected it. Quite by chance, I noticed a crack in the fan. Ran the engine with the belt off and the noise stopped. Replaced the fan blade, fixed the problem and avoided probable serious damage to myself and the car from a flying blade.

Glen

[jhowes]

I might suggest that if you use CT Jack's suggestion (which is a good one) unhook the fan belt first. Then it is out of the way and you are out of danger. Jack

[700rpm]

I used the nut the CarlG shows in post #15 on my recent engine rebuild, and I believe that for the first time ever I got that nut torqued adequately! I did it by clamping the camshaft in a vise and using a long breaker bar to get full power on the nut before I installed the cam in the block.

[Fred K-OR]

Thanks guys. Now all I need is some time to try some of these things. Will let you know how it works out once I get to it.

[Fred K-OR]

Well guys I tried a couple of things to try to find the knock in my coupe engine.

First of all I took the fan belt off, started it up, still knock.
Second with the fan belt off, I did what CT Jack suggested-that is use a rounded 1/4 inch wooden peg, took the timing pin out, put peg in hole and started engine. Pushed the pin against the timing gear as hard as I could with the engine running. Still the same knock.
Third attempt to try to find knock. My daughter who was a paramedic for a number of years gave me a used stethoscope. Took the metal end off the hoses, put the hoses against various parts of the running engine. Did all these checks on the carb side of engine. First place I tried was along the head-very little knock noise. Second was to run the hoses along the valve cover from front to back. A little knock noise. Third I run the hoses along the pan. Little noise up front be as I got toward the back of the pan, had a good knock noise.

So, does anyone have any other ideas? Am I missing something? What else should I do?
Could it still be the timing gear? Should I pull the cover off it?

Thanks for all your help so far.

[700rpm]

Fred, use a long screwdriver or dowel/broom handle, at least 16" long, to listen to your lower end. With engine running, put one end of the stick next to your ear, the other along the top of the pan at front, middle, and back. Increase and decrease the engine speed at the carb as you do this. Do the same thing along the valve chamber and the head. I think the stick will give you a more accurate indication. It sounds like bearings, or maybe wrist pin or piston slap or even the rear thrust bearing clearance. The stick will talk to you. Your next move might be drop the pan and look at the rod bearings. After that, it gets more complicated, as you undoubtedly know. Call me if you want to talk.

[trailerpark]

Have you had your distributor out lately? Is it over tightened?

[Big hammer]

Going to the other side along the pan, see if the same test is the same results

[40 Deluxe]

Originally Posted by WHN

Check the timing gear. Also try heavier oil. 20-50 works very well on older engines. 10-30 seems to me to be to light for 100 degrees.

Before you start tearing down the engine, try some inexpensive options.

Marvel Mystery Oil in your gas can help with valve noise.

MM Oil in the gas helps with valve noise?? How does it do this? Never heard of such a thing!

[WHN]

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Originally Posted by 40 Deluxe

MM Oil in the gas helps with valve noise?? How does it do this? Never heard of such a thing!

I guess you haven't spent much time reading up on old gas engines.

Some people swear by it. Some people say it's snake oil. I happen to like using it.

I am entitled to my opinion whether you agree or not.

[Tom Wesenberg]

Originally Posted by 40 Deluxe

MM Oil in the gas helps with valve noise?? How does it do this? Never heard of such a thing!

Today's gas isn't like the better gas we had in the 60's and 70's, and MMO helps to lubricate the valve stems. Today's gas doesn't have much lubrication quality, and MMO helps. I started using it a few years ago, and I also think it helps.

[40 Deluxe]

Originally Posted by WHN

I guess you haven't spent much time reading up on old gas engines.

Some people swear by it. Some people say it's snake oil. I happen to like using it.

I am entitled to my opinion whether you agree or not.

I agree that MMO is good stuff. It's just that I don't think a few ounces dissolved in a tank of gas can have any effect on valve noise. Valve noise is caused by excessive tappet clearance or severely worn out valve guides, or maybe a broken spring. MMO is of no value in such cases.

[Dtolson9]

I had a knock with my old motor and I lost the skirting on one of the pistons

[Tom Wesenberg]

The temporary engine in my 28 had a bad knock with the slightest acceleration. After I flushed out the block and radiator I got rid of the hot spot caused by the build up of crud in the rear of the water jacket, and that also got rid of the knock.

I still have a light tick, which I'm sure is a slightly collapsed piston skirt on #3 or #4. Of course this was also caused by the hot spot overheating the piston. Just gotta love all the problems cause by people running straight water.

[BILL WILLIAMSON]

If someone holds the crank, you CAN torque the cam nut to 105 Ft Lbs.
Bill Seenitdonebytheguyswife!

[john in illinois]

Fred, here is a chart to trouble shoot engine noises

http://www.foxvalleymarc.com/Tech_se...ne_noises.html

I chased a clicking knock for a couple of years,thougt it was piston slap. Ended up being a worn rod insert bearing. Thankfully the crank was not damaged and I replaced the insert.

Good luck,John.

[Fred K-OR]

Hi guys again. I still have not pinned the knock down but thought I would give you the sound of it. Maybe this is the way an A should sound.

Hope this may help.

https://drive.google.com/file/d/0B_w...w?usp=drivesdk

[glenn in camino]

Sounds like the timing gear.

[Fred K-OR]

Thanks Glenn. Maybe I had better get the old timing gasket and take off the cover and see what it is doing. Seems like I have gotten a lot of comments saying that is what it is so better give it a try.

[1931 flamingo]

If the knock was worse at the REAR of the engine I doubt it's the timing gear which is at the FRONT. JMO
Keep us updated.
Paul in CT

[WHN]

Originally Posted by 40 Deluxe

I agree that MMO is good stuff. It's just that I don't think a few ounces dissolved in a tank of gas can have any effect on valve noise. Valve noise is caused by excessive tappet clearance or severely worn out valve guides, or maybe a broken spring. MMO is of no value in such cases.

I have first hand experience with engines that had noisy valve trains but were not worn out or in need of a rebuild. Correct oil weight, for engine condition, and additives can help and could extend engine life.

Slow or sticking valves, I believe, can be helped with MMO used in gas.

I fully understand there are a number of people who think of additives as worthless. I can say I have used both STP and MMO in older engines and the difference has been amazing. Not expensive. If it helps, what does someone have to loose?

I'm not talking about oil burning, no compression engines with burned valves.

I am talking about engines that have been sitting around for awhile, or not driven very much.

I learned many years ago that I didn't know everything, and there might be good ideas or other ways of doing things, that I was not aware of. Enjoy.

[Fred K-OR]

Just an update on this situation. Still have not found the knock.

Someone suggested testing the compression. I did it with the engine warm. The following is the test results: #1=79 lbs,#2=73 lbs, #3=79 lbs #4 = 78 lbs. Not knowing much about compression results but these amounts seem to me to be pretty good-better than my Huckster. So doesn't look like any one cylinder has a compression problem tied in to a sticking valve if that is what one would expect to find from this test.

I think the next thing I will do is check the valve lifters to see if they need adjusting. This would be the next easy thing to do at this time. Will keep you posted when I get to doing this job.

[Fred K-OR]

To update, this problem, I did get into adjusting the valves. I found most of the valves were within the expected setting EXCEPT for valve number 6. It showed a setting of .027. Way over the .013 recommenced. So got it reset to about .014 and put the rig back together again. Wow, it looks like it did the job. The old engine sounds like most old Model A engines without the annoying Knock-Knock it had before.

Thanks to all your suggestions it looks like we may have solved this problem. Now all I have to do is figure out where I have an exhaust leak.

Thanks again.

[700rpm]

Glad it was simple, Fred.

[Mikeinnj]

Originally Posted by BILL WILLIAMSON

If someone holds the crank, you CAN torque the cam nut to 105 Ft Lbs.
Bill Seenitdonebytheguyswife!

Bad idea Bill. The pressure put on the cam gear teeth using this method can ruin them. Better to use a c-clamp on the side of the cam gear while torqueing the nut. This puts no strain on the gear teeth. Mike

[Fred K-OR]

Originally Posted by Fred K-OR

To update, this problem, I did get into adjusting the valves. I found most of the valves were within the expected setting EXCEPT for valve number 6. It showed a setting of .027. Way over the .013 recommenced. So got it reset to about .014 and put the rig back together again. Wow, it looks like it did the job. The old engine sounds like most old Model A engines without the annoying Knock-Knock it had before.

Thanks to all your suggestions it looks like we may have solved this problem. Now all I have to do is figure out where I have an exhaust leak.

Thanks again.

Well guys, likes I wrote to soon! The "knock" is still there.

To further report on this "knock" I did take the side cover off the timing gear to check it based on some of the comments. I did find the timing gear is great shape all the way around. Also no play with it's shaft going back and forth.

So at this point, I think I will just see how things develop and go from here until something else turns up. Thanks again for the comments.

[Ed]

Was it knocking before the timing gear was replaced? If not, you may want to check your work. It is pretty easy to remove the front cover compared to getting into other areas of the engine. If you check under the cover, don't overlook the plunger assembly. The spring may have broken, or it may be so full of gunk that it cannot move freely.

[Fred K-OR]

Originally Posted by Ed

Was it knocking before the timing gear was replaced? If not, you may want to check your work. It is pretty easy to remove the front cover compared to getting into other areas of the engine. If you check under the cover, don't overlook the plunger assembly. The spring may have broken, or it may be so full of gunk that it cannot move freely.

The timing gear was replaced about two years ago. Had no problem up until about a couple of months ago.

The problem may still be values that need to be adjusted. But for now I think I will let it go and see what develops. It may be just the "Model A" sound.

[richsfords]

Could not help myself,

"Knock Knock"
who's there
USA
USA who
usa see the U S A in a MODEL A

SORRY? it was only
a matter of time, anyway!!!!!!
(no hijack intended)

[Fred K-OR]

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Originally Posted by richsfords

Could not help myself,

"Knock Knock"
who's there
USA
USA who
usa see the U S A in a MODEL A

SORRY? it was only
a matter of time, anyway!!!!!!
(no hijack intended)

Should have assumed this was coming! Ha,Ha.