: Sts engine has this knocking sound



esimp64
12-28-07, 11:16 AM
I have a 02 STS. Every so often I hear this tappng sound. Its steady I raise the engine but it stay the same. Then goes away. I hear it on the bottom of the engine but then I think I hear it in the front but it goes away everytime and comes back I get oil level good. I'm thinking Kock Sensors but I need help does anyone know what this may be or have had this problem and can help. THanks

Submariner409
12-28-07, 12:07 PM
esimp..........Use the search function at the top right of this page....in the forum toolbars. Look for "carbon rap", "carbon knock", "WOT", "cold carbon", stuff like that.

Hopefully, you'll find that an afternoon of "spirited driving" will be a cure.

It's not the knock sensor.......these engines have a very thin "quench area" under the cylinder dome in order to control flame travel in the cylinder. Sometimes carbon, not much, builds up to the point of creating a slight tapping in one or more cylinders. The noise usually goes away when the engine warms up.

Also, before you go out to run the snot out of the engine, dump a 20 oz. jug of Chevron TECHRON fuel additive in the tank and top off with 93 octane. Do a search for "top tier fuel".

Good luck and Happy New Year! (BTW, post your car and mileage in your ^^ profile....makes diagnosis easier.)

afroney
12-28-07, 11:40 PM
esimp..........Use the search function at the top right of this page....in the forum toolbars. Look for "carbon rap", "carbon knock", "WOT", "cold carbon", stuff like that.

Hopefully, you'll find that an afternoon of "spirited driving" will be a cure.

It's not the knock sensor.......these engines have a very thin "quench area" under the cylinder dome in order to control flame travel in the cylinder. Sometimes carbon, not much, builds up to the point of creating a slight tapping in one or more cylinders. The noise usually goes away when the engine warms up.

Also, before you go out to run the snot out of the engine, dump a 20 oz. jug of Chevron TECHRON fuel additive in the tank and top off with 93 octane. Do a search for "top tier fuel".

Good luck and Happy New Year! (BTW, post your car and mileage in your ^^ profile....makes diagnosis easier.)

Couldn't have said it better! Had the carbon knock in my 01 Deville when cold. Plenty of Techron and beating the snot out of the engine. No more knock, and oil consumption cut in half

Ranger
12-29-07, 05:24 PM
Its steady I raise the engine but it stay the same.
That's not cold carbon rap.

Zorb750
12-30-07, 10:13 PM
Steering pump isn't unlikely. Belt tensioner could be too. You would think RPM linked on both, but not always, especially with the steering pump. Check motor mount, exhaust mainfold bolts, crossover bolts, flange bolts.