Engine sounds low on oil but is full

[Playthetrees]

I have a 98 Blazer LS with 145000 miles it just started tapping like low on oil but it is full it goes away after 3-5 minutes. I am thinking a oil pump is failing. Any Ideas? How hard is it to change the oil pump if it is that?

[Gooseneck]

What engine do you have? What is your oil pressure @ idle, cold? What is your pressure @ idle, operating temperature? Your engine oil pressure should be at it's peek when your engine is cold so the tapping you hear is probably lifters. Just changing your oil could be the fix. Sometimes changing to synthetic engine oil does the trick. If your engine oil pressure drops dramatically after the engine reaches operating temp it is more of a sigh of worn main bearings (this could also be your tapping) than oil pump. As far as getting to the oil pump it's usually a pretty tough job on a 4x4. Maybe someone out there can tell you if they've had the oil pan off a blazer. If worse comes to worse and you do need oil pump and or bearings this should be done by a good mechanic, one little mistake and you will be needing a new engine!

[Playthetrees]

I have the 4.3 vortec. The sound comes and goes I did notice yesterday when it was tapping that when I pressed on the gas the oil pressure went up but thte tapping continued for 5 minutes.

[Playthetrees]

Oh I forgot the oil pressure stays between 30 and 40 normaly when I acclerate it can go up to 50.

[Gooseneck]

Oil pressure is good, especially if you are getting those reading at operating temp. If you're not already using synthetic oil or a friction reducing oil additive, it might help if it is the lifters.