98 Yukon oil pressure on the lower side and mechanical whirring noise?

[olliec420]

Does the 5.7 have the same oil pickup tube gasket common issue as the 5.3s? I ask because my oil pressure is good according to the 10psi + 10psi/1000rpm rule. But it is on the lower side, at or right below 20 at idle and 1000 rpms. At or right below 40 at cruising. A bit over 40 on cold start up. Now these numbers are all from the gauge, not the scanner.

I only ask because the last few times ive taken it out, its sounded funny. Like a mechanical whirring. Almost like a chain drive or something? I know that not how they sound normally, and I dont like it. Figured Id run it by you. Also seems like the fan surges a bit. This is a cold start, the whirr goes away after while.

 

[Eman85]

Gauge?? If it's the indicator on the dash you're going by it probably wasn't very accurate from the start now 27 years later it's just a guess. If you want to know oil pressure connect a mechanical gauge to the place where the sending unit goes. A 5.7L has no gaskets or O-rings in the oil pump or the pickup, it's the same design as 1955. If you hear a noise up front remove the belt and start it and see if the noise goes away. Listen closely to the alternator, they have bearings that wear as do the idler and tensioner pulleys.
Never saw oil pressure on a scanner.

 

[exp500]

Change the oil! Switch to a summer weight, up to 20-50max.
Also test spin your fan clutch by hand, eng off. cold and hot. Feel for wobble and resistance when hot.

 

[GMCChevy]

That sounds like typical power steering pump, alternator, tensioner type noise. Can't tell from video you should be able to pinpoint it under the hood.

Our 99 isn't very high on the oil pressure guage when it's warm but is high cold and moves around at different rpm. If there's no ticking lack of oil noises and no low pressure light don't worry about it. The guages aren't the best when they're old and the sensor could be off too. If you're worried get it checked with a real guage.

 

[olliec420]

Oh ok, yeah maybe on the belt drive. I was thinking the whirring was the chain drive under the cover. Maybe problem with oil pump. I'll check out the pulleys.

 

[Hoesgottaeat2]

Use a long screwdriver and touch each rotating assembly while running i.e. A/C pump, P/S pump, alternator, etc and put your ear to the end of the screwdriver. It acts as a stethoscope of sorts.
This can help you narrow down the culprit here.
HF sells these too.

Mechanic's stethoscope