99 Olds Intrigue GLS Engine Knock

Hey all, I have a 99 Olds Intrigue GLS with the 3.5L Shortstar engine. It has a definite knocking sound that occurs on startup, not too noticeable in the car with doors closed, but definately there.
It has not gotten any worse and oil consumption is about average for what I hear for this car. Sometimes needs more between changes and other times it does not need any additional. Crankshaft postion sensor already replaced. What could this be? Think it is a definite sign of impending engine failure or is it something that will just be a minor annoyance? Sounds like bad lifters, but, im no mechanic. Car has 65,000 miles and runs well otherwise. thanks, Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Does it require opening up the engine?
TIA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.