There's a couple possibilities there.... You might still have something in the cylinder from the plug that was giving you trouble. Or, you may have a marginal lifter, that finally gave up while it was waiting for oil pressure after the oil change. If your bud has access to a bore scope, might not hurt to poke it in there, and have a peak around. If you don't find anything fairly obvious when you pull the valve covers..... something to consider.

 

It's certainly possible something is still there. Last night we pulled the plug and let run again for 30 seconds or so to give it another try at blowing anything out that might be in there. The lifter is a possibility. The thing that confuses us is that I had it at my house, drained the oil, then refilled it after I couldn't get the old filter off. Then it got driven a good 30 or 40 miles. After that we parked it and did the plugs. The tapping didn't appear till after we finished the plugs. In between driving it and doing the plugs the oil didn't get touched.

I'll ask him if he has a bore scope. If he doesn't, I'm sure one of his co-workers has one we could borrow for an evening.

 

Something else you may want to try...

Run number four up to TDC, firing position. (valves closed) Pull the plug, and blow some high pressure air in there. If you hear something rattling around, keep up with the air until it blows out.

 

Yeah, definitely worth trying before we start pulling valve covers.

 

I pulled head on a nearly new Pontiac once because I couldn't find the tapping noise, got it checked and re-installed. Still tapping, finally I found a plug wire that was broken internally and the hei was strong enough to arc the gap and fire the plug but it raised hell doing it. That would also explain the check engine light.

 

I forgot to mention that we scanned the codes with a code reader. One was an O2 sensor code, the other was a problem with the fuel injector on cylinder 4. We don't know where the O2 code came from, but the fuel injector we caused when we were messing with it trying to figure out what was going on. We cleared them and no codes came back while we were running it last night, at least none that we didn't cause. Not saying it couldn't be an issue with the plug wire though. Although I would think in that case the tap would have gone away when we pulled the wiring to the fuel injectors one at a time because there would be no fuel to fire.

 

The plug would still fire though.

A spark arcing to nearby metal can be pretty loud...... an easy test is to wait until dark.... start the engine, and then spray a fine mist of water on the plug wires. If any of them are marginal, you will see the light show.

 

Ok, we'll give that a try next chance we get. The plug wires are all brand new Mopar wires, but that doesn't mean one can't have an issue.

 

If the wire is broken internally like the one on my Pontiac you won't see a thing because it's inside the insulation not arcing to metal. Not saying yours is, could be either way.

 

It was definitely a sticky lifter. We put half a pint of Seafoam in the oil (bottle called for 1 pint per 10 quarts) and started it up. At first the tapping got quieter, but was still noticeable. We let it idle until everything was up to temperature. Then I took it and drove it for about a mile, then came back, parked it, and turned it off. Started it back up around 30-45 minutes later, and the tapping was gone completely. Drove it back to my house (about a 15 minute trip) and along the way the tap would show up under load during the beginning of the trip, but by the time I reached my house it was gone under all conditions. Drove it to the dump and into town on saturday, and the same thing occurred. During the first 10 minutes or so of the drive the tap would be there under load, but not during idle, then it went away completely and didn't show up for the rest of the day. I plan to leave this oil in it for 600-800 miles, unless I check it and it looked really dirty, then I'm going to change it, and also put in a bottle of Rislone with the new oil.