I have a 2000 ssei with 150k yesterday as i was driving i notice a miss then by the time i made it home it was tapping too. i pulled the front plugs and #3 cylinder plugs gap was completly closed but showed no sign of damage. i replaced it the miss went away but i still have the tapping sound that seems as though its coming from the top front or middle of the engine. its a loudest at idle. I pulled all the push rods to see if i had one bent but they were all straight. any help would be appreciated

Does it sound like lifter noise? I'd be very concerned about the gap being closed up on the spark plug. Other than that, how did it look? Any coolant on it? Have the lower intake manifold gaskets been replaced? Losing any coolant?

No their were no other signs of damage other than the gap being closed. it was however wet but i believe it was fuel. No the intake gasket have not been changed and yes it loses antifreeze a very little at a time never the less it loses it.

I'm concerned that you may have a lower intake manifold failure. Here'* a recent thread on one.

http://www.bonnevilleclub.com/forum/...369&highlight=

I suggest that you also read the techinfo article.

http://www.bonnevilleclub.com/forum/...e=article&k=38

That deals mostly with the upper intake for the L36, but the symptoms and resulting damage would be the same if you're getting coolant into your oil. Pay special attention to the information on the aluminum lower intake gasket. Getting oil in the coolant could cause bearing problems, as well as lifter problems which may be what you are experiencing. Check under the oil cap. Any chocolate milk coloring there of the oil? Anything on the dipstick? That plug got damaged somehow, and I'm wondering if maybe from compressing coolant in that cylinder.

Ya know, I have a similar problem. I would say mine sounds more like a "flapping" kind of noise. And I only hear occasionally while idleing. I DO NEED a tune up but there is no coolant loss. I'm gonna take my digital camera down tomorrow and see if I can't record it. I wonder if its like what your experiencing.

I have the same issue on mine sorta...but its hardly able to hear it..I think its actually coming off one of the pullies. a little clicking sound.

How about you take the belts off to see if the problem still exists..it could also be a supercharger coupler noise your hearing.

AMENDED:

Typically when I hear my noise it accompanies a rougher than normal idel as well.

Sapphire, could it be the harmonic balancer slapping? They say to grab the belt and tug it both directions to see if there'* rotary motion of the balancer pulley relative to the crank, and there would be if its bad.

Let'* address the pinched spark plug anode. The only thing I can think of that would cause that is debris getting caught between the piston and the spark plug. That could be nothing more than a large chunk of fire-hardened carbon breaking off the piston top.

Obviously once the gap is pinched off you will have a MAJOR misfire (like no fire man!).

I can't really tie this into the noise you are hearing...... unless the piston experienced some catastrophic event which allowed a piece of piston to let go, damaging the plug, while at the same time causing piston slap. That'* a pretty lame scenario though. Piston slap may be caused by a broken piston skirt, but if the skirt broke I don't see how the piece that broke off could work its way up the side wall to the top of the combustion chamber. If a cornner of the piston top let go that could certainly cause plug damage but I doubt it would result in noise unless the piece of piston were banging around in the combustion chamber. The sound would be like shaking a steel pipe can with nail inside.

Sooooooooooooo.... I'm freakin' stumped on this one.

.........a steel pipe can??? Did I write that? I meant a "steel pipe". Man, when am I going to remember to pruuf reeeed?