Need Help Top End Knock

Shawno

New Member
Jul 30, 2017
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hey guys My 1989 fox has developed a knock which seems to be coming from the top end. It only starts after it's been running for 10-15 min. I've checked the rockers and push rods every thing seems fine there. Just seems weird it only happens after it been running for awhile I figure if it's cam or crank it would happen as soon as it was started. Anyways any help or suggestions would be great
 
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mikestang63

SN Certified Technician
Aug 27, 2012
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top ends don't knock, they tap/tick
if you are hearing a knock then it is mist likely a rod or main bearing

Are you hearing a ticking or knock sound.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Try this, start the engine and let it idle, when the knock starts pull one plug wire at a time to see if the knock stops. Of course all that may tell you is you possibly have a rod bearing problem.
It could be that bad or as simple as a header gasket leaking, you could also take a long funnel and hold the big end to your ear and point the little end around header flange area and valve cover/lower intake area to isolate the tic/knock, sorry can't tell you anymore than that from a post.
 

Shawno

New Member
Jul 30, 2017
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Ok so it seems the knock is coming from cylinder #5. It happens when I rev it up, once I let off it had a knock. It's fine while the rpm climbs but soon as I let off I can hear it for a second or so