Wondering if anyone has had long term success with overhauling rolls Royce KRG engines or any engines for that matter with aftermarket parts?

I work on a DP class 2 Korean built shuttle tanker. We have been experiencing problems with our LT pressure dropping off. It seems we are getting air in our system and cannot trace where it is comming from. We have to bleed the air from the suction side of the pump which dont make any sense. Please ...