Rebuilt 3.4 With Poss Noisy Lifter

I just had my 97 Venture with 3.4L rebuilt by local machine shop. When putting engine back together, we had a prob with the head and coolant dumped into the crankcase. The engine was ran without knowing that coolant was in the crankcase. Drove the van for approx 10 miles during break-in process. Also idled the engine quite a bit to bring the coolant up to appropriate level (of course, the coolant was dumping into the oil).

During the whole process, the red oil light (idiot light) on the dashboard has been on (sometimes it will fade and go away, but still comes back). The amber-colored 'Low Oil' light is not coming on. It's possible that the idiot light is coming on due to improper ground, but not sure.

Now that we have the head problem corrected and the coolant removed from the crankcase, there is a loud tapping noise which we believe is coming from the top of the engine. Sounds like a bad lifter, but unsure. This noise developed during the 10-mile trip to break-in the engine mentioned above (keep in mind, coolant was unknowingly in the oil during this trip). The engine is actually running good and does not seem to have a miss. I have drove the van a couple of times for approx 10 miles to see if it is a lifter and that it would prime itself under driving conditions and begin to operate properly. During these trips, the noise will go away during certain rpm's, but always returns when I take my foot off the accelerator. Between trips, I changed the oil to attempt to remove any coolant still remaining in the crankcase. During the 2nd trip, the range of rpm's where the noise went away increased (less noise than on the first trip), but it is still there during idling. Also, on the second trip, the idiot light went off immediately after start up - got my hopes up that this issue was resolved, but was disappointed when the light returned at the end of my trip.

Any help on this would be so much appreciated. A newly rebuilt engine and all these probs to get going again. Thanks in advance.

I am just taking a guess, and I hope it helps, but could the noise be a fuel injector rather than a lifter? I assume the lifters were replaced during the rebuild, and it would be a lot easier to replace an injector rather than a lifter. I have had cars with "noisy" injectors, and they ran fine for years, the only problem was the noise. If it is a lifter, one of the few oil additives that actually do work are the ones that are for noisy valve-trains, and lifters in particular. Also, fuel injector cleaner actually does work if it is an injector.

I hope this helps, and I hope it is a minor problem!