Chasing the knock.

Garagekulture13

Garagekulture13

Senior Member
I just purchased my 2nd Model A title says 1932 but it's a 1931 to me. Any way, it has a knock. It has been sitting in an 80 year old man's house for sometime. I had a previous problem of it not running well after a carb rebuild but it was solved with another carb. The car starts good, runs good, and drives out good but does have a knock. So I started investigating. I am a novice so if you see something in the pics by all means tell me. All the lifters are free. I do see a couple new valves. Pulled the cover to inspect the timing gear and is worn pretty badly. I have a new one on the way. I just tried to drain the oil and when I pulled the plug nothing came out. I had to stick a screwdriver in the hole to get the oil to come out. I then dropped the pan. Other than about a half inch of sludge I didn't find anything in the pan. Video is just for noise reference and was taken when I was trying to figure out the carb problem.

https://youtu.be/3R3eLKlvVmU

https://youtu.be/X1Jxiqp16Xw
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Any way, it has a knock. It has been sitting in an 80 year old man's house for sometime. I had a previous problem of it not running well after a carb rebuild but it was solved with another carb. The car starts good, runs good, and drives out good but does have a knock. So I started investigating. I am a novice so if you see something in the pics by all means tell me. All the lifters are free. I do see a couple new valves. Pulled the cover to inspect the timing gear and is worn pretty badly. I have a new one on the way. I just tried to drain the oil and when I pulled the plug nothing came out. I had to stick a screwdriver in the hole to get the oil to come out. I then dropped the pan. Other than about a half inch of sludge I didn't find anything in the pan.
Click to expand...

Did you not check the oil level on the dipstick when you bought it?
 
Can you tell about where the knock seems to be coming from ?

Have you checked the lash of the timing gears ? Anything more than about .009" and they'll rattle. Yours don't look very good from the picture, but, checking the lash is whats needed.

Running the engine with the timing pin inserted and putting pressure on the gear is sometimes a good way to determine if the gear is bad/worn.
 
That thing needs a bath....before you clean valve chamber block crank and cam oil passages with wood dowels so you dont get debris in them
 
Patrick L. said:
Can you tell about where the knock seems to be coming from ?

Have you checked the lash of the timing gears ? Anything more than about .009" and they'll rattle. Yours don't look very good from the picture, but, checking the lash is whats needed.

Running the engine with the timing pin inserted and putting pressure on the gear is sometimes a good way to determine if the gear is bad/worn.
Click to expand...
I ran with the side cover off and it sounded to me to be coming from the front of the engine. That's what led me to pull the timing gear cover. I will check the lash.

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I've had a couple of motors that looked like this. By the amount of dirt and sludge and the timing gear I'd say the oil wasn't changed often. Look at the scoring on # 2 and 3 cylinders. The Pistons are probley slapping.
 
Your car was likely built in 1932, but is of all 1931 parts. A friend of mine has a wide-bed pickup registered like that. Good luck with finding and fixing you noise.
 
It is really hard to tell by the picture, but it looks like your timing gear teeth are worn real bad.
To find the noise it is best to short out each cylinder one at a time. Do this before you tear it down. This way you can tell if it is a rod, main, or piston. It also tells you which cylinder or which main is knocking. It would not tell you if it is a timing gear.
 
George Miller said:
It is really hard to tell by the picture, but it looks like your timing gear teeth are worn real bad.
To find the noise it is best to short out each cylinder one at a time. Do this before you tear it down. This way you can tell if it is a rod, main, or piston. It also tells you which cylinder or which main is knocking. It would not tell you if it is a timing gear.
Click to expand...
I did this but not really any change in the knock.

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Since the pan is off, you should check the rod and main bearing clearances with plastigage, and check the babbitt condition of the caps. There are lots of threads on this in the search function. I also put 4x4 block of wood under the front wheels--the extra room makes things easier.
 
Just for comparison, here is a laminated fiber gear with about 1500 miles on it.
 

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I did just notice both motor mount bolts are loose and I have not touched either.
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Might be a good time to yank that engine and go through it carefully. The dirt and sludge can't be doing anything but hurting. The car is nice enough to deserve a pretty, quiet engine, and give you a ton of piece of mind while you enjoy it.
 
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