just bought a 96 blazer 4x4 with 177,000 miles for 1200 bucks has nice leather and all....everything was fine when i was looking at it and purchased it and drove it home.... i didnt drive it for a couple days cause had to wait to get my tag legal.... well went to leave to day and everything was good got a little down the road and noticed at stoplight my oil pressure guage goes almost to 0 close enough to make the check gauge light flicker on and off but when im driving down the road the gauge reads about 30psi sometimes will get right at 40 but doesnt really go any higher...... also looked and noticed that the oil pressure switch has been replaced so am i looking at putting an oil pump in it or has anyone else had this problem.....also when at idle does sound like it has a slight knock but when i rev it up it goes away

 

A knock at 177k isnt abnormal. Was the oil level good? If so the pump might be bad, but if the pressure is changing when you throttle up, it might be the oil pump screen is plugged. Also, the oil pressure sensor could be the culprit. Thats what I had to change in mine a few months ago.

 

yea i was thinkin the oil pressure sensor also but looked at it and it looks like it has already been replaced does anyone have good advice or a write up for dropping the oil pan what all new parts and gaskets will i need when doing this it is a cast oil pan i heard that the cast past serve some sort of strucutral purpose between the engine and tranny any help would be great..... it is 4x4 by the way