996 - Think I ruined the 1-3 top end my motor?

[miscou]

I've been getting a loud tap that sounds like it's coming from the the top end of 1-3. I dropped the motor this weekend to investigate. I realized that I put the 1-3 oil pump cover in upside down the last time I had the engine out. I've driving that way for about 4500 Miles. The the tap leads me to believe I've worn a lifter, or worse. Anyone ever made this error before and figured out what gets destroyed? I'm surpised I didn't get any warning lights or indications of poor oil flow from the car. Hoping maybe someone can shed some light on the results of this blunder.

[Dharn55]

Do you have a 3.4 or 3.6 engine? Are you talking about the 1-3 scavenger oil pump?

I can tell you that back in 2009 when I was in the process of fixing my intermix I had my engine in and out several times. During one of the drops/cam cover/cam removals I put both scavenger pumps in reversed. I had on-going low and erratic oil pressure problems that I could not figure out. I even replaced the main oil pump, still had erratic pressure problems. I finally ordered new scavenger pumps. When I went to install them I found out that I had reversed the pumps. I changed the old pumps to the proper orientation (ended up returning the new pumps) and the problem was gone.

I am guessing that I put on a couple of thousand miles with them reversed. If you do some searches here you will find some posts on the oil pressure problems I was having. In any case I have almost 20,000 miles since then and the engine is running strong. I did replace the lifters, but I think that was before the pump reversal.

If you have a tapping from a lifter you may need to replace it. And if you are replacing one you may want to do all of them.

Does the tapping go away after the car warms up?

[Dharn55]

Remember that the function of the scavenger pumps is to take oil from the heads and return it to the sump. This is also done by gravitational flow. This should have no specific effect on the lifters.

[miscou]

Thanks, that makes me feel a bit better, and explains why I never got any oil pressure warning lights. I've replaced all 12 of the lifters on the 1-3 bank, and I'm still getting the tapping. My fear is that I have a block in one of the small oil passages that provide oil to the lifter sleeve.