99 Olds Intrigue GLS Engine Knock

"Chris" wrote

Two things come to mind with this engine. A very uncommon but serious problem with these engines was the failure of the front balance shaft bearing. This bearing is like a cam bearing that you would find in a small block chevy engine, same idea. We've had about 3 of the 3.5 engines that had this bearing actually come right out of the block and then the balance shaft just begins to spin right into the aluminum block (which essentially destroys the block). Usually, the sure sign of this happening is no lack of oil pressure on the guage, but you get a lot of lifter noise, simply because the front balance shaft bearing is right in line with the oil passage that goes from the block and then up to the cylinder heads. As a result, a failure of that bearing causes the oil pressure to drop off up to the heads.

The other item that we see much more of....is just carbon buildup on the pistons which can cause this noise. There is a de-carbonization procedure that GM uses for oil consumption on the Northstar engines. We use this same procedure for carbon buildup on the pistons, and for the most part it's fairly successful.

We don't see too many engine failures of any kind with these

3.5 engines. Pretty solid little engine.

Ian

Does it require opening up the engine?

TIA

"Neo" wrote

No, you pull the plugs, inject the cleaner into the cylinders and let it sit for between

2 and 3 hours. Then it gets sucked out, plugs re-installed, oil drained and refilled, given a good hard road test, then change the oil and filter again.

Ian