bwill03z

Going to pull my pass valve cover to attempt pinpointing where this "tapping" is coming from on a cold start. I assume it is not a problem to start the car with the valve cover removed, right? Also, using a stethoscope where is the best location to put the metal tip to try and locate which cylinder the sound is coming from?

Pounder

you might have a bunch of oil spraying around !!

bwill03z

Hmm ok so sounds like a bad idea.... how about how to identify which cylinder the tapingp is coming from then?

Vetteman Jack

Sometimes diagnosis can be messy. Hope you can find the source of the tapping noise.

Dirty Dog

People have been running engines with the valve covers off, without damage, forever. It can be messy, but not damaging.
One old trick... if you have a spare set of valve covers, cut the top out of one set so they basically form a wall around the head. Helps contain the mess a little.

Bill Curlee

Just do it. Yes, it gets a little messy but, nothing that going to hurt anything. I've done it several times.

Hell, I've even run the engine with the front timing chain cover off.

Better yet, I've run the engine in the car with the transmission/ differential and TT removed to make sure that I didn't have any vibrations after I installed a new clutch.

BC

grantv

Beat me to it... pretty common in the old days (easier when there was one coil and it wasn't on a valve cover). Helps contain the mess a lot.

bwill03z

Ok thanks guys. I will do it and try to make some sort of splash gaurd with some cardboard.

c4cruiser

Used to be that parts stores would stock a set of rocker arm clips that fit over the pushrod end of the stamped-style rockers. The clip simply fit over the end of the rocker and around the pushrod. That would keep the oil from spurting thru the hole in the pushrod and going everywhere They didn't affect oiling, just stopped the squirting.


Starting the engine cold would most likely increase the flow of oil from the pushrod/rocker so make sure you have a way to collect oil. With the engine running, try pushing down on the pushrod side of each rocker. If the tapping noise quiets down, it may be a lifter that has drained after sitting. Does the noise go away once the engine runs for a minute or two?

bwill03z

After cranking on a cold motor it takes about 1 min for the noise to show up with is progressively getting louder. Sound completely disappears after 5-10 mins at idle. It does not return until motor is cold again.

4XLR8N

I use an engine stethoscope, similar to what a doctor uses to listen to your heart except the end of it is a metal rod. You would be amazed what you can hear. Found many valve train issues thru the years with it.

bwill03z

I have one and used it the other day but still could not pinpoint the tapping. Im surprised though because that thing is very sensitive. The only place I could really hear tapping is when I put the rod at the front of the block just behind the throttle body

4XLR8N

That suggests something deeper in the engine than upper valve train to me. But I understand why you want to be sure before tearing into it. Like others have posted, I too have run engines without a valve cove to try to find a problem. Never done it with an LS engine though, so not sure how messy it would be...

4XLR8N

One other thought - did you put the stethoscope on the fuel injectors? Sometimes a bad injector can make a noise that sounds a lot like valve train issues...

heavymetals

The noise can be caused by the cold thick oil pumping up the lifter.
I have a similar problem, but have adjustable rockers.
I have a pretty good feeling one is adjusted just a little too tight (my problem) as the ticking goes away after the engine gets warmed up.
I am just to lazy at the moment to pull off all the stuff to get at them for an adjustment session.

aaronc7

I have a tapping at idle when the engine is cold too. I haven't dug deep yet, but mine sounds like it may be more the front of the engine-- one of the pulley tensioners or idlers im hoping.

Something else you can do to help isolate thing before you go too deep is take a quick 10 second video or so of the engine running in its tapping state. Slow the video down to 1/8 speed and count the taps and convert to taps / min. A lot of valvestrain events only happen at 1/2 engine rpm so you'd expect ~400 taps/min. When I had a cracked piston and completely dead cylinder, I got a tapping noise at exactly 400 times/minute (800 rpm idle).

Potent68

Sounds like it could be the wrist pin knock that LS1's are sometimes plagued with.

bwill03z

I did put the stethoscope around the injectors but maybe not right on them. Here is a pic showing the only area that I could really notice the tapping through the stethoscope, it was really pronounced but kind of faint.

4XLR8N

Did you pull the belts and run it to eliminate any noise from accessories, tensioners, etc? Just trying to eliminate the easy stuff first before you dig too deep. Another idea, sometimes a bad plug wire will allow the spark to jump to ground without firing the plug. This also makes a ticking noise at valve train speed. Run it in the dark and see if you can see a spark jumping to ground...

bwill03z

Thanks I will check the plugs. I haven't pulled the belts yet but I will before removing the valve covers again. I removed the pass valve cover awhile back and found nothing but haven't done the driver's side yet. The reason I only pulled the pass cover was because the tap was pretty obvious to be louder on the pass side but I will pull the drivers side soon too.