Are These Engines Known To Tap?

iamvillani · Oct 17, 2012

I recently bought a 99 GT with a 155k on it. Car is in great shape runs great pulls wonderful. However i noticed when its warm there is what sounds like a valve tap from approx 1600 - 2400 rpms. Has anyone encountered this? Oil is good. No leaks. I dont hear any loud knocks. When its cold its sound normal. Also the tapping is barley noticeable when in nuetral. Thanks.

Gearbanger 101 · Oct 17, 2012

4.6L OHC's are generally pretty quiet engines, but a little noise isn’t uncommon. Tap could be any number of things. Could be as serious as a broken piston ring land or rocker arm, or it could be as small as a noisy lifter or an exhaust leak.

I’d first try to diagnose where the noise is coming from. A compression test couldn’t hurt either. If everything checks out, try running a can of seafoam through the engine. What are you running in it for oil? Something a little heavier than the recommended 5W20 will help quiet a noisy valve train down some.

iamvillani · Oct 17, 2012

Gearbanger 101 said:
4.6L OHC's are generally pretty quiet engines, but a little noise isn’t uncommon. Tap could be any number of things. Could be as serious as a broken piston ring land or rocker arm, or it could be as small as a noisy lifter or an exhaust leak.

I’d first try to diagnose where the noise is coming from. A compression test couldn’t hurt either. If everything checks out, try running a can of seafoam through the engine. What are you running in it for oil? Something a little heavier than the recommended 5W20 will help quiet a noisy valve train down some.

I run Valvoline Max Life. I belive 5w30. Whats a good heavier oil but for winter months? Tried to locate noise but like I said in nuetral its hard to locate it as it doesnt do it when i manually raise throttle with hood open. When driving I can hear it better if i lean in towards the middle of the dash more towards the passanger side. Thanks.

Kilgore Trout · Oct 17, 2012

Check spark plugs for tightness.

usaf_branham · Oct 17, 2012

heh, my transmission makes a tapping noise in neutral... it happened after i got pissed at the wife 5 years ago and had the 1st to 2nd grind... instead of backing off and trying to re-seat it into 2nd, i forced it. Ever since, the shifter handle shakes just a tad every time it taps. When it happened I thought I spun a bearing because it was LOUD. Now its pretty quiet and only noticible by me.

trinity_gt · Oct 17, 2012

Sounds are the hardest thing to diagnose over the IntarweBz especially without a sound-clip.

Having said that, no, these engines are not supposed to "tap." High-mileage engines may suffer from timing chain tensioner arm or guide wear and you can get noise from that. If the engine has been run low on oil and been revved all to hell it's possible to hurt a rod bearing. If the engine has seen severe detonation a piston may be damaged and rocking in the bore.

If the noise gets more intense or louder under load you might have a look at the plug torque as Kilgore said. As well, if this is the case (louder under load) it's not a valvetrain noise...

1fun281 · Oct 18, 2012

The injectors make a really loud clicking sound? Almost like an electrical ark sound? but shouldnt hear it while driving

iamvillani · Oct 18, 2012

Yeah I know its hard to tell but still thought I'd ask. Strangest thing is if I accelerate upto say 4500rpms you dont really hear it. Guess a shop will have to diagnose. Never ran low on oil or anthing. Thanks

Are These Engines Known To Tap?

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