94 cold = no knock, warm = knock??

[jimmythecow]

4.3l, when the engine is cold, there is no knock at all. when the engine warms up it will start to knock, but its only at idle. when you rev it it goes away. used a mech stheths (sp) and it sounds like its from the bottom end, oil pan... ideas?

also, its not really steady, it seems to wander in and out. like its something loose hitting it or something.

im out of ideas, any help is apprec.

[2000CAYukon]

If it was my truck, I would pull the oil pan to look for a bad bearing.

What mileage and what grade oil are you using?

//2000CAYukon

[jimmythecow]

140k, 10w 30 and a quart of power punch. its been a beatifull rig, but was lent to a friend, who isnt great at shifting and reved the engine up really high, now i got that noise. supose that has anything to do with it?

[2000CAYukon]

Originally Posted by jimmythecow

140k, 10w 30 and a quart of power punch. its been a beatifull rig, but was lent to a friend, who isnt great at shifting and reved the engine up really high, now i got that noise. supose that has anything to do with it?

It is possible that over reving the engine is related. If the noise is down low in the block, the bearings are suspect.

A friend of mine has a 88 Jimmy (4.3L). He had a intake leak that allowed coolant to get into the block and he spun a bearing. The noise showed up warm at idle. The engine was pulled and rebuilt. The crank had to be replaced and one connecting rod.

Like I said, I would pull the pan to see how the bottom end looks.

//2000CAYukon

[jimmythecow]

the intake leak that would not mix in the oil, show it would look normal. hmm.. interesting. well im gunna pull the pan and see about putting in another oil pump, it seems that when its colder, more pressure, it stops. but warmer, less pressure, it knocks. so i changed the oil and tried heavy oil. but no go. so... when i yank the pan we'll see