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Car will run but with loud knock top end rockers seem to operate normally oil is

(1999 Ford Escort)
in Croydon, PA on April 06, 2015
fine was running fine then began knocking at start up 1/2 hour later is it possibly the timing belt and how much damage would driving after that cause. car can still run rough and loud knocking
Displaying 1 answer & 8 comments
Popular Answer
on April 06, 2015
Very possible exhaust valve seat has dropped out of cylinder head holding valve open and piston is contacting valve face... Compression test will quickly confirm!... It's usually on # 4 cylinder for some funny reason... Bore scope is a must before engine disassembly to determine if beyond reasonable repair!!
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on April 06, 2015
wouldn't this leave slop in between rocker, valve stem, and pushrod with motor cranking?
on April 06, 2015
YES!.. Valve is being held down by dislodged seat, it can't come back to correct height.. Thus slack in rocker arm .. Over head cam so no pushrods.. > valve lifter... Which cylinder is this on? Closer to drivers side??
on April 06, 2015
there appears to be no slack in any cylinder valve cover off and engine cranking
on April 06, 2015
Bump engine over slowly and check each rocker arm..You should have determined which cylinder before removing any parts... By unhooking one plug wire at a time to see which cylinder made NO change in rough idle!.. Remove plugs to see if any are wet with gas.
on April 06, 2015
car knocks so badly and runs so rough did not want to keep doing any more damage only valve cover is off easy to replace but it almost sounds if it is multple or all cylinders with engine running no noise was heard while cranking motor with ignition unplugged
on April 06, 2015
Damage is already done!... Hope you have good luck with it!
on April 06, 2015
would the timing belt cause this and is it worth trying to replace timing belt
on April 06, 2015
NO.. Read first answer again.
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