well today i came home was geting ready to shut the truck and it started shacking pretty bad so i shut it down really quick. started it back up and it did the same then and now there is a little taping sound comeing from the passager side of the truck.i check the oil it was low like just on the dipstick. so i added some but it still dose the same thing anyone got any ideas?

 

Cylinder missing. (as in not firing, I am sure it is still there....) Check plug wire routing. If that ain't it, the tapping sound could be a loose rocker arm, or a valve problem....

 

i checked all the plugs they are all good the truck dosn't sound like its missing
and i guess the only way to see if its a loose rocker arm would be to take the vavle covers off oh goody

 

Is the engine still shaking while making that "little tapping sound", or is it just the tapping you're asking about?

If it's still shaking and if the exhaust note has changed, you may have a collapsed lifter, and maybe a bent pushrod because of it. It's easy enough to spot if you pull the valve cover on the affected bank -- if it all seems tight and straight enough, start it up and listen to the rockers with a stethoscope (or a cut-off broom handle) to find the one that's noisy. Just be sure to keep both yourself and those plug wires out of harm's way.

Another neat trick, one that's not so common now that timing lights are going the way of the dinosaur, is to hang the inductive pickup on the coil wire and use the light to strobe the trouble spot so you can see what's happening. The light won't strobe reliably or usefully if you go much above idle, though. An adjustable timing light is handy for this because you can change the firing time of the light this way and that to see things more clearly. Usually, if there's much slop you'll see one rocker stuttering or wobbling unlike the others.

If it's a collapsed lifter you might just as well do them all if they're the factory originals. Running the engine with too little (or too much) oil, and especially if the oil is thin (too hot or too old) is tough as hell on lifters so the others will have seen the same abuse that broke that one. If you have a collapsed lifter, give it a new pushrod in the same hole, too.

It could be something else, so rule out ignition and fuel delivery problems before you start wrenching.

 

Failing/failed harmonic balancer?

 

harmonic balancer was replaced less than 6 months ago its not that i thinck im gonna have to pull the covers off and take a look at her

 

if its a collasped lifter im not shore but i probley would have to take the heads off? and same gose for a bent push rod?

 

anyone else have any ideas ?

 

well i pulled the valve covers off to not find anything abnormal everything was tight nothing was loose. still need some help pretty shore one cylinder is not fireing

 

Figure out which one and test for compression, fuel, and spark...

You might try pulling plug wires one at a time to see which one when pulled doesn't make it run even worse. That would be the cylinder to focus testing on.