MTFCA Forum

Back in the past there has been a list posted on this forum of possible causes of specific engine noises (knocks, taps, rattles, etc) that we hear from a Model T engine. Example: a tap that is heard at moderate speed, with no load. this list would be a starting point- not a sure fix.

This list detailed the most common noises and the "possible" cause of the noise. Can someone re-post the list? I want to save it this time!

Thanks, Scott. That was quick. The manual that you have is different from the 2 that I have. Mine don't have those pages.

Here's one that was sent to me by email. I don't know the source.

What would be very helpful is a HD audio recording of a properly running engine; eventually audio of all of these knocks would be great to have too.

They all make some unusual noises, and the firewall and floorboards are not insulated as in modern cars, so the noises are more audible in a Model T. Some of the noises are just vibrations. Such noises as brake rods under the car as you go over a bump or the vibration of the choke or carburetor adjustment rod where it goes through the firewall or dash.
Some noises are in the transmission and others pass forward through the driveshaft from the rear axle. So one must become familiar with his/her own car and notice if the noises are new, or increasing. Then address those.

Engine knocks. A constant clicking is caused by the valves. Sometimes a little play or loose clearances with the tappets. Those are not harmful. A sharp tapping noise in one or more cylinder noticeable especially when pulling hard, such as on a hill or first starting out. This can be decreased by slightly retarding the spark. Usually caused by piston slap from loose pistons which slap against the cylinder wall. Once in a while, it happens on an engine which has been bored oversize and the top edge of the piston hits the head.
More serious knocks would be loose rod bearing or wrist pin. These are most noticeable when going along at a steady speed or very slightly decelerating. It is a rapping noise. Goes away when slowing down on compression or hard acceleration. This is also a serious knock and should be tended to soon or danger of "throwing" a rod damaging the crankshaft.
Carbon knock or compression knock is almost unknown these days with higher octane fuel. It is caused by pre-ignition where the fuel ignites before the spark occurs. This knock causes a "pinging" noise. Excess carbon in a hot engine can also lead to this type knock or extremely advanced spark can also cause it.
Norm

From Norman Kling's post on 9/21/22 at 10:04 am:
"Once in a while, it happens on an engine which has been bored oversize and the top edge of the piston hits the head. "
This once happened to me with a "Z" head. Those heads don't have a lot of clearance between the piston and the head and can knock especially on acceleration. My solution was to grind a little off the head at the interference point and the problem was solved. Grinding a little off the head did not cause any other problems.
Keith

Steve Jelf wrote: ↑

Wed Sep 21, 2022 11:50 am

I don't know why pinging is called pinging. It sounds like a knock to me.

Point well taken. Verbs used to describe a sound can be interpreted differently by different people. Compare Steve's response a to quote from a response further up "This knock causes a "pinging" noise." Saying that the engine is making a knocking sound is very ambiguous, and generates numerous solutions to endless possibilities. Along with sound there is the possibility of vibration - something loose. Various noises knocks, pinging, taps, rattles, grinding, sputtering, coughs, etc need to be described.

Does this work - if not...
The term "Engine knocking" is used to describe two basic sounds both consistent to tapping rapidly on something. The "knock" sound is more like knocking on a hard surface, while the "pinging" sound is more subtle harder to hear.

"Pinging" or "spark knock" can sound like a knock, a rattle, like a pebble hitting a window, or a little like glass breaking. Backing off the throttle will stop it. Opening the throttle will bring it back. It does not occur at idle or light throttle running. It can be caused by overheating, lean mixture, too much spark advance, a valve running hot due to poor seating, excess carbon in the combustion chamber, excess oil burning, and hot spots caused by a poor fitting head gasket, clogged cooling system, bad or wrong type spark plugs, or cylinder firing out of time. Modern gasoline will prevent most pinging, even if there are issues. Very low octane gasoline will ping in a Model A or Model T under some conditions, even if everthing is working as it should. Such gasoline is not sold in the USA and has not been for a long time.