What causes an engine to knock?

Answer by  6ixk (1156)

A piston hitting, or a valve spring out of alignment. Either of them can cause the engine internals to come upward in the engine hitting it against the head, or the valve cover. Depending on which is causing it.

Answer by  Mark87 (33)

An engine can knock if the engine has been run low of oil at any time and the mechanical parts have not been lubricated properly. Also over revving an engine can cause damage to the internals making it knock, when metal comes into contact with other parts of metal and the pistons do not run truw

Answer by  bigdaddy (150)

usually a knock comes from spun rod bearings or main bearings. the knock should be the same speed as the engine to know its from bottom end not twice the speed that would be valvetrain. Change your oil and catch into something with a fine screen on top. When done draining check screen for metal particles.

Answer by  jkareckygmailcom (85)

An internal knocking sound from an engine usually means one or more of the bearings have failed or one or more or the pistons are not operating properly. Low oil pressure can also cause an engine to make noise.

Answer by  vicki94 (477)

Engines knocks when the fuel ignites before it suppose to. It can damage the pistons as well as the engine. Let your car warm up before you put it in gear and use more expensive gas for a while. The engine can get too hot so watch the temperature gage.

Answer by  Amber40 (24961)

Typically engine knock can be caused by two things. Either their has been a mechanically failure and the rods has been damaged to the point it physically knock against the block. The other from of knock is detonation. This is caused by using bad quality or low octane gas leading to a premature detonation in the cylinder.

Answer by  Allstar (2071)

A fuel/air mixture can spontaneously explode if compressed too much. If you use too low a grade of gasoline, it can cause this detonation, or knock.

Answer by  Amber40 (24961)

One reason is that you are running to low an octane fuel. This causes detonation and a knock. Another reason is that the engine's internals have gotten damaged causing interference.

Answer by  jay34 (250)

The causes for an engine to knock are mostly in on cylynder not enough or too much bustion problems. It could be a rod went out causing a knock.

Answer by  jon40 (440)

The wrong grade of gas could cause your car engine to "knock". Use high octane for high compression because the higher the octane the more it resists ignition knocking ispredetonation

Answer by  N31J (148)

Sunny boy this is very serious stop driving your car immediatly and take it to your local mechanic, the most likely problem is to little oil.