Lound engine knocking appeared?

[yukonxl1500]

I just developed a loud engine knocking/metal slapping sound on start up on the drivers side toward back of engine. It is loud at the begining of start up then goes away. It returns after I shut off the engine and restart if it has been sitting for a while.

I cant think of anything I did that would have caused and engine damage, although the day before it started I was driving aggressively to the ER when my daughter busted her lip and was bleeding exessively. Mainly flooring it from the stop postion, but never going over 50mph due to driving in side city limits.

My oil pressure is fine, actually it is better than normal. Normally it will drop below 40 (to about 30) when it is at idle and goes to about 50-60 during driving. All day today it stayed at 40 during idle. No smoke from tail pipe, water in oil, no oil or water leaks anywear. Just the knocking.

I am hoping I just developed the "piston slap" and not a blown rod bearing. But how to tell the differnce?

Thanks

 

[667theneighbour]

Not knowing the year of your car this is just a guess. 2000-2002 5,3 can develop a knock in the valves. It's rather common. I had a 2000 Hoe that got this after oil-change. Grit can come into the lifter. You can try an engine flush. remember to keep the rmp at appx 3000 for the duration of the flush to get full effect. It helped a bit on my 00 Hoe, but didn't completely remove it. To do so I guess you have to take out the valves and clean manually.

Just remember not to come close to the exhaust with your arm afterwords. I've got a big scar because of this and I did it 3 years ago.

Just my 2 cents.

 

[yukonxl1500]

It is a 2000 Yukon XL 1500 2wd, I replaced the engine about 50k, back in Dec 04. I don'tknow what engine they replaced it with other than a 5.3.

 

[MURFS_HOE]

Mine will do the same thing to if it's cold outside on first start

 

[667theneighbour]

You could try an engine flush or a pint of diesel, or ask a GM shop.