LOW OIL PRESSURE ON 2007 GMC SIERRA 1500. CHANGED

Oil pump shaft broken, Spun main bearing on crankshaft will cover the oil hole on the crankshaft stopping oil flow to the engine.

If the oil dipstick shows good oil level, the problem is usually is a failed pressure sensor, which I would have checked ASAP at a shop. If the oil level is very low, top it up, but to avoid serious engine damage you may need to have it towed ASAP to a shop for repairs.

Probably oil pump

Sounds like an oil pressure problem. The clacking sound is most likely the lifters are collapsing due to loss of oil pressure. You may have a failing oil pump.

I doubt it....It could be a totally worn out engine.

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if it shows low oil level its possible bad "level sensor "located on oil pan.if it shows low oil pressure possible oil "pressure sensor"

the knock sensors are located below the intake plenum,or,upper intake manifold as some call it, they screw into the lower intake, the front one is sensor 1, the rear is sensor 2. it is wise to change both if you have some miles.since you are going to be buying a gasket set to do this job.the sensors are cheaper than the gaskets.

if it is electrical oil pressure sensor I would start there. The best way to see if you have a major problem is to use a mechanical oil pressure tester. Take off the oil pressure sensor and put the mechanical tester on. The tester should come with a Gage. If it comes within your trucks oil pressure range than all is fine and replace the sending unit and see if that don't help your problem.If the tester runs high then the oil pump is bad or your cam-bearings could be the problem. But with cam-bearings you would usually get a low reading.