97 C1500 5.7 350 Oil Pump issues

[97Layzboy]

My gauge on the dash keeps dropping pressure when I slow down or just starting up but after a few seconds it jumps up. during the time that it is low it makes a slight knocking sound. From everything I have looked up online trying to figure if its the pump, pickup tube, or the oil pressure sending unit but I am uncertain as to what to replace first.

I called a local mechanic the other day about the issue and first off he doesnt replace internal parts anymore. but mentioned that it could be the crankshaft and bearings having too much wear that its causing the low oil pressure. He also said to have the oil pressure checked with a gauge that would take 3 hours and $80 to do get that reading.

Let me know if this sounds right or if someone could point me in the direction of a good how to video on changing the oil pump out completely as I am not above not doing it myself. Any help is appreciated.

 

[evilunclegrimace]

Find another mechanic, It does not take three hours to put a mechanical gauge on the engine to check the pressure.

 

[97Layzboy]

I thought that sounded a little ridiculous. He said they check it cool and then check it after the engine is hot. I just need confirmation that it is definitely the pump and not like the crankshaft. That comment has me questioning the whole ordeal but I havent heard of that mentioned in any videos or other areas i have read for this type issue.