: 02 sts N* Engine knock



LACADMAN
09-13-07, 03:48 AM
Can anyone advise me on my N* I have had the car since 34000 miles and now have 72000. It's certified but will end in 08 I have had a knocking sound on a warm engine most notable when oil has been changed and fresh. The local dealer has decarbed the engine twice and I have opened it up many times. Last year the dealer said it was piston slap and replaced pistons and rings. But one year later it still does the same. I had it looked at by another dealer and they said they have seen this on 01-03 N*s They say its normal and i'm fishing for the unkown. I have owned a 94 that went to 134000 and never herd any noise except for valve train taping after 100000+ miles, until I traded in for this one in 04. My father has an 01 sts that has the same sound but not as loud. Has anyone out there had the same problem or if anyone knows what I"m dealing with Thanks in advance!

AJxtcman
09-13-07, 08:04 PM
First thing. I mic out every cylinder with a bore gauge. When I started at this dealership no one new how to use a dial bore gauge. I am the only one that checks the cylinders at the dealership currently. One other guy will check a cylinder from time to time. I have a spread sheet on my PC and I enter the numbers in. Most of the time I see a .0025 to .003 reading on tapper and out of round. The spec is .0039. I see them up to .005 and then the block are junk. Did they check yours?
That is a big question!

Next is the noise that the engine makes. It could be the purge solenoid. They are loud and knock. You can place your hand on it and see if the rhythm matches.
Does it sound like a sewing machine?
If yes That is a normal sound. The engine has parts that are moving around inside of it. It is normal to have a machine type sound coming from an aluminum engine. The noises penetrate through the block.

LACADMAN
09-14-07, 12:34 AM
Thanks for the info I dont think they checked the block. this makes sense because the second dealer asked if it was double tap or single tap. When he herd the sound he said it was a double tap which he heard louder from the oil pan area by the side were the pullies are. He felt it was the piston tapping the wall. But then gave me a look like they couldnt do anything. They ended up decarbing the car again which Did not solve the problem. I am planning to take it by back to the dealer that replaced pistons is their something I could mention about bad blocks on these model years or have them look for something in particular by the way the car idles fine and power is fine and burns a quart every 3000 miles Thanks Again

AJxtcman
09-14-07, 07:06 AM
Thanks for the info I don't think they checked the block. this makes sense because the second dealer asked if it was double tap or single tap. When he herd the sound he said it was a double tap which he heard louder from the oil pan area by the side were the pullies are. He felt it was the piston tapping the wall. But then gave me a look like they couldnt do anything. They ended up decarbing the car again which Did not solve the problem. I am planning to take it by back to the dealer that replaced pistons is their something I could mention about bad blocks on these model years or have them look for something in particular by the way the car idles fine and power is fine and burns a quart every 3000 miles Thanks Again

This is not a bad block issue:nono:
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Look at it this way:hmm:
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Northstars have low tension rings. This can cause them to stick or just to consume oil. The oil that burns will cause carbon deposits in the combustion chamber. The original pistons with the carbon build up will contact the head and bind in the dwell time. When it is bound up and the dwell time occurs the piston will snap over in the cylinder.
Example: make a fist, place your other hand over the top of the fist, now pivot your wrist. The motion of your wrist moving back and forth is a rocking motion.:hide:
This snapping and rocking motion will cause damage to the pistons and block over time. On a cold engine with looser clearance and 3000 rpm you can imagine the damage to an aluminum short skirt piston. If you drive 5k to 10k miles you will be just fine, but if you go 20k to 50k with this knock (certified car with 100k warranty) the block will be worn out.
In my opinion this is neglect. Remember I stated this is from oil consumption. If you are using 2 quart or more per 3k miles and not repairing the engine it will cause this type of wear.:cool2:

Submariner409
09-14-07, 11:18 AM
:sneaky: Just for grins and kicks, search the forum for "WOT". Read up on how to do a foot-to-the-floor 1st/2nd run to redline and coastdown. Prep the fuel: dump in a 20 oz. bottle of TECHRON, top off with 93, drive a hundred highway miles, then RUN THE SNOT OUT OF IT. Don't try to break it, just run it hard. Keep your 5W-30 oil level halfway up the dipstick hashmark. The N* was designed and built to run.

LACADMAN
09-15-07, 01:11 AM
This is the most that anyone has been able to explain to me thank you for your wisdom. I have been chasing the dealers for 3 years for info but getting no were. From what I understand as long as I'm not burning more oil than i am now I should be OK. Oh by the way one of the first things I read about at this site is WOT. I Have been doing them for over two years now and opening it up when ever I'm on the freeway. Thanks again