GMC Yukon Knock at Startup

1998 GMC YUKON AUTO 5.3L 2WD 145,000 miles . At startup, I hear a knock or thump noise coming from the engine. This lasts for a second or two and then stops. At the same time I notice the oil pressure gauge slow to move up.
It eventually does and when it does the noise goes away. The engine runs good and has been well serviced and taken care of. Is there a possibility that the oil pump needs to be replaced or is this a sign of future engine work to come ?

Thanks for your help,

Yukon Man

I don't think you have a 5.3L engine. Those did not come out till 1999 in the trucks and 2000 in the Yukon, the new body style from the 88-99 models. You must have a 5.7L if its the old body style.

Sounds normal to me for an engine with those miles its going to take a few seconds for pressure to build.


What type of oil filter and oil is being using in the SUV?

Should be a 5W-30 or a 0W-30, not 10W-40 or 20W-50. Some oil filters have been known to cause engine noise because they don't have or using a poor quality anti-drain back valve ADBV). The ADBV is a small nitile rubber or silicon device that prevents the oil from draining backwards thus taking a little longer to pump oil back thru the filter on the next start. Use a AC Delco filter and good 5W-30 oil and see if the noise persists.