Valve train picture - bad lifter?
03-27-2011, 02:08 PM
#1
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Valve train picture - bad lifter? We are getting ready to pull the heads on my son's car in an attempt to troubleshoot what we think is a bad lifter and we were looking at the valve train and noticed only one rocker was lower than the rest on both sides of the engine.
Is this a dead giveaway to a bad lifter?
I have labeled it in the pic below. Sorry for the noob question, but we are new to the whole internal motor stuff and feeling our way in the dark..
Is this a dead giveaway to a bad lifter?
I have labeled it in the pic below. Sorry for the noob question, but we are new to the whole internal motor stuff and feeling our way in the dark..
03-27-2011, 02:46 PM
#3
If the lifter was bad (collapsed) then the lifter would NOT be pushing up on the pushrod and causing the rocker arm to rock downward to open the valve.
You got it backwards.
Looks like just that specific valve that you have marked is just opening because the lobe of the cam is upward against the lifter like it is suppose to be.
What syptoms are you having?
Usually when a lifter fails it will (collapse) which will cause the valve that it operates via the pushrod and rocker arm to not open at all or not as much as it should. Usually its not at all.
A lifter is nothing more than a hydraulic (oil) pump that becomes almost solid with respect to the pushod and its travel. The lifter is pushed upward as the cam lobe spins around and contacts it. When this happens the lifter pushes upward on the pushrod and on the other end of the pushrod it is against a rocker arm and it is caused to rock upward. The opposite end of that rocker arm rocks downward which pushes down on the end of valve stem and opens the valve in the cylinder head.
You got it backwards.
Looks like just that specific valve that you have marked is just opening because the lobe of the cam is upward against the lifter like it is suppose to be.
What syptoms are you having?
Usually when a lifter fails it will (collapse) which will cause the valve that it operates via the pushrod and rocker arm to not open at all or not as much as it should. Usually its not at all.
A lifter is nothing more than a hydraulic (oil) pump that becomes almost solid with respect to the pushod and its travel. The lifter is pushed upward as the cam lobe spins around and contacts it. When this happens the lifter pushes upward on the pushrod and on the other end of the pushrod it is against a rocker arm and it is caused to rock upward. The opposite end of that rocker arm rocks downward which pushes down on the end of valve stem and opens the valve in the cylinder head.
03-27-2011, 03:12 PM
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03-27-2011, 05:19 PM
#5
Could be rod knocking, valvetrain problem or exhaust leak. (remote possibility a cracked flywheel or backed out torque converter bolt)
I need to hear it revved up about 300-400rpm more off idle. Then let the throttle snap shut and hear it wind down. You will hear a distinct rat tat tat sound as the rpm drops back toward idle speed if its a rod bearing getting ready to poop on you.
Valvetrain noise you should be able to tell with the valve covers off and engine idling. Get your ear down close and see if its at the top near the rockers or if the noise is deep down inside the motor.
I need to hear it revved up about 300-400rpm more off idle. Then let the throttle snap shut and hear it wind down. You will hear a distinct rat tat tat sound as the rpm drops back toward idle speed if its a rod bearing getting ready to poop on you.
Valvetrain noise you should be able to tell with the valve covers off and engine idling. Get your ear down close and see if its at the top near the rockers or if the noise is deep down inside the motor.
