Knocking sound coming from the head once shut off.

[Beach_Jeep]

My 81 CJ7 has the 258 inline 6. After running it even for a minute or so the motor will knock. Is this normal with a plastic valve cover? If not, what are your thoughts?
Thanks guys,

Beach Jeep

 

[84_CJ7]

The term "knock" can be very subjective. A hard knocking sound could be a broken main bearing which is allowing your crankshaft to move up and down - not good. But a knock that is more like a ticking sound could be a stuck lifter which could be cured with an oil change. If you're not sure I'd take it to someone trustworthy and let them have a listen.

Scott

 

[Snitty]

where does this "knock" sound like it is coming from... upper, lower?

 

[Deerhunter30]

My motor has a "knock" once the motor is turned off. It is not a real loud knock and continues for about a minute or so once the motor is off. It sounds like it is coming from the head area.

 

[84_CJ7]

My motor has a "knock" once the motor is turned off. It is not a real loud knock and continues for about a minute or so once the motor is off. It sounds like it is coming from the head area.

Thats all of the hot metal in your motor cooling down.

 

[Beach_Jeep]

Yep, thats what mine is doing also. Its sounds like its coming from the valve cover. Knocks for about 1-2minutes and then stops.

 

[Snitty]

oh ok ok... so it is AFTER it is turned off?? that is normal