knocking from valve covers

[homerojr]

While I was cruising and making some runs (not overrevving), after a stop I noticed the car idled terribly and there was a knocking sound from apparently the driver side valve cover. Pretending it wasn´t anything serious, I turned off the car and checked for spark plugs wires disconected, or vacuum leaks, as the symptoms are pretty much alike, but a quick inspection didn´t show any failures. The sound is like a bolt or metal pieces (oh god...) being shaked inside a cup. Maybe a loose rocker arm or a bolt or valve springs? Or in the worst scenario, a dropped valve, or broken puhrods? Any clues?
Thanks for any info

P.S. What a way to begin the weekend....

 

[302fordracer]

heaven forbid....valve lifter tapping???

 

[302fordracer]

I had the same thing happen to me in an older import car and it was valve lifter tapping...the idle would go to hell and this metal tapping sound could be heard

 

[281pony]

pull your covers and tighten the rockers. i had the same problem before, loose bolts.

another problem, unlikely, but it would be a blown head gasket. my car did it when the water started mixing with the oil.

should be a simple or plain obvious fix.

 

[homerojr]

God bless you guys...maybe not that bad uh? If valve lifter tapping, what´s the fix?

 

[Stangfreak95]

I had a bad luck last summer and I got that sound not too long after a run. It was a broken rocker stud so the roller rocker had fallen, and the pushrod was hitting the valve cover. It actually cracked the valve cover and had to get it welded

 

[302fordracer]

if it were valve lifting tapping the fix would be to replace pull the lifters and replce the ones with holes because they usually tap cause there is no oil in them as there should be on startup however this is not likely the case cause you said that it was after doing some runs so the lifters should have been full of oil regardless of whether they have holes in them..

 

[liv2ride]

I have a '90 GT with 44k original miles. Since I have owned the car I noticed that when the car has been at running temp for 15+ minutes there is an obvious tapping type noise that appears to be coming from the left bank (driver side). You can hear like a slight valve tap but there appears to be a more solid type of tapping comes from deeper down - my guess a collapsed lifter. I know that our cars have roller lifters but are they hydraulic rollers? What is the possibility that one has collapsed or is sticking? I have had the car for about 2k miles or 6 months. The oil is semi synthetic 10w-40 and I changed it when I first got the car. I am thinking about changing it to full synthetic to see if that helps.

What is the chance the noise can just be a loose rocker bolt? I don't run the car hard and it does not appear to have had a rough life. I got the car and it was completely stock with the exception of the spark plugs and tires. I have gone through the entire car and everything that I replaced had to be done because of age and nothing else.

Thanks in advance.

 

[95 Snake]

Pull those vc's and check the lifters and rods. I wouldnt run the engine until you check it out, snapped a push rod once and it was the demise of that engine.

 

[281pony]

i agree. dont drive it without pulling the covers.

like i said on a couple different ocassions. mine were tapping, one was a loose rocker bolt and one was a blown head gasket and water mixing with the oil.

 

[Slow5.0]

In last April '04 ,righ after track when I got home I find out my Stang is fu**** up, took me 3 weeks to find out whats wrong, it was broken intake valve retainer ,but i was lucky valve was stuck in midle and didn't him piston (I drive 200 miles like that) I got rebuild kit, and after 4 months I put new heads BUT now I have taping from all rockers

 

[95Cobra302]

I kinda have the same problem with my 96 V6. When you accelerate at full throttle and the rpm's reach almost redline I hear the same sound. but it doesn't do it any other time. What do yall think?? Sorry to interupt thread

 

[MysteryMachine]

i had a tapping and I replaced the lifters. Sound went away for a while then came back sounded like it was coming from the pass side then i noticed my driver side valve cover was loose i tightened it up no more tapping. I was very suprised. But I will say if you decide to change the lifters do them all at once its a good amount of work to change them. Would be a big pain to get in there change 1 or 2 put it back together then have to tear it apart again to change more. Good Luck hope its nothing big

 

[OutLawSE]

I recently had a similar problem. Had a bad knocking from the passenger valve cover, car idled horrilbe, and lost all power. Ended up being a broken valve spring on the #1 cylinder.

Thank God I didn't drop that valve.
Check the valve springs on that side.

 

[homerojr]

Thanks guys. Just to let you know the problem was a worn harmonic balancer. As in medicine, sometimes the complaint doesn´t relate very well to the real disease. I´ve ordered a precision products new one and spacer. Any tips on install?