Pontiac Repair: Main Bearings 3.1, blown head gasket, main bearing cap

Question
About a year ago a blown head gasket dumped coolant into the pan of my 95 Grand Am 3.1. I replaced the head gaskets, put in fresh oil and coolant and drove the car for a month til the oil pump screen loaded up with crud and starved the rod bearings til one began knocking. I replaced the rod bearings and oil pump and everything has been ok, except for lower than normal oil pressure, but still adequate. Today, 10,000 miles later I noticed the mains are beginning to knock so now they have to be replaced too. My question is, can the mains be replaced by merely dropping the pan again like I did the rod bearings or does the engine have to come out? Thanks for your help. By the way, the car has about 100,000 miles on it but is in super good condition except for this issue. Thanks again

Answer
Hey Jim:

To do the job right the engine should be pulled you cna replace the rod and main bearings in the car all but the rear one. The rear one has the read main seal in it. In order to replace that bearing the seal has to be removed and the only wayto do that is to either take out the transmission and remove the fly wheel or take the engine out. The rear main seal is in the back of the block and the main bearing cap is 1/2 of the sealing surface for the seal the block is the other half. Also if have had issues with low oil pressure and "crud" in the engine have the cam bearings relaced as well. My guess is they are wiped out to. That has to be done in a machine shop. You more than likley looking at having to replace the crankshaft or have it machined and if the cam bearings are shot the cam may need to be replaced as well. This is not a cheap simple repair.. Good luck :)