Model A Engine Noise and worn timing gear

J

jguedel

New member
Hello

I am a new Model A owner having bought a 29 Tudor at the Hershey RM Auction. This engine has a knocking noise. We pulled the oil pan to discover that all rod bearings appear tight but the timing gear is missing many teeth. The engine ran fine, starts fine, seems to have enough power. The knock comes and go's at different rpm. Would the timing gear cause this noise? would a bad main bearing cause the timing gear to chip and be causing the noise?
Thanks for any help.
John
 
Hello and welcome to the Barn. In answer to the cam, yes it can make the knocking noise you have . Check the spring in front of the timing gear it can let the cam walk forward and backward causing a knock.....Dave
 
If the timing gear is missing teeth, it's gotta go! Otherwise it will leave you stranded somewhere really inconvenient.
 
It is common for the A's timing gears to go bad. You won't know about the bearings until you get it running with a new gear. I recommend an aluminum gear, they don't break. It is a good sign that the rod bearings are in good shape, they usually go before the mains ... but not always. The gear can be replaced without pulling the engine, many have been replaced along side of the road. Have fun!
 
when you replace the cam gear make sure the dimple on the front of it is deep enough so the timing pin will go in deepenough to be felt when your timing the engine to #1 piston at tdc, if its not modify it a little so the pin has a positive feel when inserted
 
Sounds like the cam thrust plunger is either stuck in its bore in the timing cover, and/ or the spring behind it is broken.

Replace Cam gear, Thrust plunger, and spring.

Bet your "bearing knock" goes away.

Went through this on my '28 Coupe last summer. Replaced the ancient & failed Fibre gear with an aluminum cam gear, plunger, and spring from Bratton's. No more "bearing knock".

Also no excessive noise from metal cam gear.
 
Eye ball the crank gear when you get the cam gear off, I've seen alot of worn out crank gears and they will tear up a new cam in no time. Walt
 
Walt Dupont--Me. said:
Eye ball the crank gear when you get the cam gear off, I've seen alot of worn out crank gears and they will tear up a new cam in no time. Walt
Click to expand...
When I replaced my timing gear (with a bronze one) I was advised to replace the crank gear at the same time and to make sure they came from the same place.
 
Also when you get the cam gear, get the socket that fits the cam gear nut so you can tighten it properly, instead of the hammer and chisel method that was probably used to install the one you are taking off. You will need to grind off the burs so the socket will fit properly. Iceman
 
Replacing the crank-gear at the same time as the cam gear is recommended, and the ideal way to do the job; in my case, I was pushed for time to get my car back in service, and I was only looking to extend the working life of an already-tired 87,000 mile engine...

Mine has racked-up another 1500 miles with the new aluminum gear against the factory steel gear, with no seeming adverse effect.

SC Frank
 
Special Coupe Frank said:
Sounds like the cam thrust plunger is either stuck in its bore in the timing cover, and/ or the spring behind it is broken.

Replace Cam gear, Thrust plunger, and spring.

Bet your "bearing knock" goes away.

Went through this on my '28 Coupe last summer. Replaced the ancient & failed Fibre gear with an aluminum cam gear, plunger, and spring from Bratton's. No more "bearing knock".

Also no excessive noise from metal cam gear.
Click to expand...

Frank. You are the man. Took your advise and the noise is gone
 
If you don't have Les Andrew's Red Book', I would recommend getting it. You will need a special tool to remove the nut on the timing gear. Andrew's book gives step by step instructions. Bert's part # camshaft wrench A-6260-T
 
You have to jack the front of the engine up to get good access . When you do this remove a bolt each side from the rear engine mount so the engine can pivot as you lift the front . If you dont do this you can crack the flywheel housing .

John in very freezing Suffolk County England .
 
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