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Valve noise on start-up

What causes a valve tap noise upon start-up of a cold engine--Chevy 7.4 liter Vortec?

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  • 142 Answers

Sticky lifters... I had a similar problem on my chevy 350. One quart of Marvel Mystery oil took care of the problem (2 weeks after use).

if that doesn't help, perhaps try some slick-50. The object is to make the lifters free themselves a bit.

Good luck.

Posted on Apr 16, 2008

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Engine got a knocking cold start, silint when hot


It has developed a clicking engine noise on a cold start. After the car has warmed up, the sound goes away. ... Clicking or a sharp tapping from the valve cover on top of the engine would point to a valve train noise. A dull tapping or slapping sound from the side of the engine block would point more toward piston slap.4 Nov 2011

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Most engines now use hydraulic lifters and they can leak a little, this causes space between then lifter and the push rod. This results in a tapping noise that goes away when they get warm or fill back up.

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I have a 1998 chevy 1500 with a 4.3 liter engine,after it sits overnight it takes a while to start. After it is warm it starts fine and runs good,it happens after its cooled down


I would start by checking fuel pressure via the schrader valve on the fuel line (near the rear of the intake manifold). The vortec engines needed considerably higher fuel pressure than most to start cold, and it is quite common for a weak fuel pump to cause a cold only no start condition with that engine. You should see around 50-60 psi with the key on / engine off for about 3 seconds. Also, if the pressure drops very quickly after a few seconds, the fuel pressure regulator could be to blame.

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Lost compression and now there is a loud knocking noise in my 454 vortec engine


Bent valves would be number one cause. Check the timing. If you lost time, your valves are tapping the pistons causing the knock. When the valves tap the pistons they bend and don't close all the way, so the cylinders cant make compression.

Oct 17, 2012 | Chevrolet Chevy Cars & Trucks

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How do i adjust valves on a 4.3 vortec tbi motor


The 4.3 liter vortex uses a hydraulic lifter. There is no valve adjustment. If you hear a lifter tick than there is either a bad lifter or something broken in the valve train. Something yo can try for a sticky lifter is add 1/2 a can of seafoam motor tune the oil. Start the engine and let it run until the noise goes away. Then change the oil. If the noise doesn't go away than you have bigger issues. I have yet for the seafoam to not fix a sticky lifter especial in the 4.3 liter which we see quite often.

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Lifter


It could be lifters but its more likely that your not getting oil to the top right away. Probably plugged oil passages in the cylinder head. Remove the valve covers and clean it out. Change your oil and see if it helps. The damage may alreay be done though

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I have a 96 chevy blazer with a 4.3 vortec rough


Do a compression test on all of your cylinders when it is cold. Backfiring is a sign of a worn valve seat allowing mixed fuel and air (lit by spark) to be forced back into the intake. You will probably see compression loss on one or more cylinders.

Also... there is a chance that the EGR valve is not totally seated when the engine is cold with just a small blow by. The EGR valve seats coke up over time with black gunk.

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Replacing pcv valve on 2002 Chevy Silverado 2500 HD Vortec 6 Liter engine


driver side valve cover in the back of the cover. if it even has one, sometimes the cover has been replaced with a later style that uses a baffle instead of a pcv

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2001 Chevy Metro


Check Utube for lifter tap, valve tap, and rod bearing noise. If you pull each spark plug one at a time, plugging it back in after each one, the tapping will go away if it's a rod bearing. At any rate, on your next oil change add some valve-medic or similar additive for valve noise. Make sure you follow direction or you will get massive lifter tap if you pour it into a cold engine.

Oct 29, 2008 | 2001 Chevrolet Metro

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