The Ford Barn

1crosscut · 08-19-2021, 07:14 PM

Did you check to see if the timing gear is loose?
Have you used a mechanics stethoscope to try to locate where the sound is coming from?

mass A man · 08-19-2021, 09:37 PM

I could hear it in your video--this may sound inane to some, but could it be a harmonic vibration of something else loose on the truck? Seems you really know the A engine and inspected it fairly thoroughly. I'm at a loss-sorry.

john charlton · 08-20-2021, 01:41 AM

Pleased you changed the oil pump although it was a good repair I could not have put that back in the engine . The video does show your problem with clarity actually the scenery looks very English except you are on the wrong side of the road !!! A very unlikely longshot exhaust pipe harmonic rattle in the rear clamp . I would remove the spark plugs and spin the engine over on 12 volts to see if you can locate the knock location .You wont harm the starter motor they are a very rugged unit as long you do not use for extended periods . My gut feeling is that is a top end noise but did not show up when you shorted out the plugs . We are all baffled I think this is a job for Sherlock Holmes ( and Dr Watson) !!! Keep us updated please .

John in Suffolk County England .

katy · 08-20-2021, 11:10 AM

Drive at 25-30 MPH, decelerate a bit and then accelerate a bit. If it knocks when decelerating and goes away when accelerating you have a loose rod.

old ugly · 08-21-2021, 09:27 AM

does the noise change when you press on the clutch?
ou
tom

nkaminar · 08-21-2021, 10:07 AM

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Definitely linked to the engine. Not a rod bearing or main bearing. If you play back the video at 1/4 speed you can hear a gear noise associated with the knock, so I would look at the gear on the crankshaft and the camshaft. Check the plunger and spring at the front of the cam gear and as Crosscut said, check to see if the cam gear nut is tight and that the fiber gear has not come loose from the steel hub.

It is knocking all the time and not the clatter when low torque on the motor that would be indicative of a rod bearing. Nor is it the deep thud of a main bearing when accelerating.

Another possibility is the oil pump drive gear on the camshaft or on the shaft that is vertical to drive the pump and distributor. Since the oil pump was cracked that may indicate a problem there.

But at 1/4 playback speed you can hear the gear noise.

If the screw holding the distributor is too tight or if there is something tight in the distributor that may be causing this knock. Take the distributor out to check for excessive drag and don't over tighten the screw when putting it back in.

I would advise not to drive the car until you find and fix the knock.

08-19-2021, 07:14 PM	#21
1crosscut Senior Member Join Date: Feb 2011 Location: Lincoln, Nebraska Posts: 1,918	Re: 1931 Pickup Engine Knock Did you check to see if the timing gear is loose? Have you used a mechanics stethoscope to try to locate where the sound is coming from? __________________ Dave / Lincoln Nebraska

08-19-2021, 09:37 PM	#22
mass A man Senior Member Join Date: Jun 2010 Location: Danvers, Ma. Posts: 714	Re: 1931 Pickup Engine Knock I could hear it in your video--this may sound inane to some, but could it be a harmonic vibration of something else loose on the truck? Seems you really know the A engine and inspected it fairly thoroughly. I'm at a loss-sorry.

08-20-2021, 01:41 AM	#23
john charlton Senior Member Join Date: May 2010 Posts: 1,304	Re: 1931 Pickup Engine Knock Pleased you changed the oil pump although it was a good repair I could not have put that back in the engine . The video does show your problem with clarity actually the scenery looks very English except you are on the wrong side of the road !!! A very unlikely longshot exhaust pipe harmonic rattle in the rear clamp . I would remove the spark plugs and spin the engine over on 12 volts to see if you can locate the knock location .You wont harm the starter motor they are a very rugged unit as long you do not use for extended periods . My gut feeling is that is a top end noise but did not show up when you shorted out the plugs . We are all baffled I think this is a job for Sherlock Holmes ( and Dr Watson) !!! Keep us updated please . John in Suffolk County England .

08-20-2021, 11:10 AM	#24
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,074	Re: 1931 Pickup Engine Knock Drive at 25-30 MPH, decelerate a bit and then accelerate a bit. If it knocks when decelerating and goes away when accelerating you have a loose rod. __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

08-21-2021, 09:27 AM	#25
old ugly Senior Member Join Date: Aug 2021 Location: alberta canada Posts: 585	Re: 1931 Pickup Engine Knock does the noise change when you press on the clutch? ou tom

08-21-2021, 10:07 AM	#26
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 4,006	Re: 1931 Pickup Engine Knock Sponsored Links (Register now to hide all advertisements) Definitely linked to the engine. Not a rod bearing or main bearing. If you play back the video at 1/4 speed you can hear a gear noise associated with the knock, so I would look at the gear on the crankshaft and the camshaft. Check the plunger and spring at the front of the cam gear and as Crosscut said, check to see if the cam gear nut is tight and that the fiber gear has not come loose from the steel hub. It is knocking all the time and not the clatter when low torque on the motor that would be indicative of a rod bearing. Nor is it the deep thud of a main bearing when accelerating. Another possibility is the oil pump drive gear on the camshaft or on the shaft that is vertical to drive the pump and distributor. Since the oil pump was cracked that may indicate a problem there. But at 1/4 playback speed you can hear the gear noise. If the screw holding the distributor is too tight or if there is something tight in the distributor that may be causing this knock. Take the distributor out to check for excessive drag and don't over tighten the screw when putting it back in. I would advise not to drive the car until you find and fix the knock. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 08-21-2021 at 03:45 PM.