: Valve clatter at cold startup



FLEALAMI
09-15-04, 12:33 PM
Hi everyone, brand spanking new guy :worship: . Hope someone can help me. My 2001 Deville runs wonderfully but when started first thing in the morning the engine makes a tapping noise or valve clatter which goes away after a few minutes. I'm assuming this is due to lack of lubrication when cold, but I've never experienced it with other engines. Is this normal for the Northstar?

Thanks,
Flea

caddydaddy
09-15-04, 01:33 PM
It could be carbon build-up on the tops of the pistons hitting the cylinder heads, and causing the pistons to slap when they are cold. Try running the car hard 0-60 a few times and see if that helps.
This is a common occurance on the newer Northstars.

Anthony Cipriano
09-15-04, 02:05 PM
Yes. More likely to be excessive carbon buildup in the combustion chambers as described. Harmless but the noise is annoying. Common in Northstars that are not "exercised " enough. Try a few WOT blasts to clean out the carbon and read my posts here:

http://www.cadillacforums.com/forums/showthread.php?t=226&page=3&pp=20

FLEALAMI
09-15-04, 03:22 PM
Thanks, I'll try the WOT. I'll report on the results.

Flea

PMBLACK12
09-15-04, 05:07 PM
Yeah I've had the same noise in my 2000 ESC. Very annoying. At first I thought it was the hydraulic lifters in the valvetrain until they pump up with oil, but when I put my ear to the top side of the engine and the bottom, it sounded as if the noise was louder towards the bottom of the engine, which really worried me becuase I know the 4.9 engines like I have in my '92 Seville develop a similar noise due to the rod bearings wearing down. So I switched to Mobil 1 10W-30 last fall and the noise was still there, although a little quieter and went away a little quicker, once the warm weather came though it went away entirely. So I assume that once the cold weather returns so will the noise. Though I'm pretty sure now that it is just the lifters as they pump up with oil and not a rod bearing or anything like that, thanks to this board as I've heard quite a few other owners express the same complaint and everyone's fealings are always that it is the valvetrain. I wouldn't worry about it, my car had about 40,000 miles on it last fall when it started making the noise and now it has 107,000 miles on it and still running very strong!

Anthony Cipriano
09-15-04, 10:15 PM
Yeah I've had the same noise in my 2000 ESC. Very annoying. At first I thought it was the hydraulic lifters in the valvetrain until they pump up with oil, but when I put my ear to the top side of the engine and the bottom, it sounded as if the noise was louder towards the bottom of the engine, which really worried me becuase I know the 4.9 engines like I have in my '92 Seville develop a similar noise due to the rod bearings wearing down. So I switched to Mobil 1 10W-30 last fall and the noise was still there, although a little quieter and went away a little quicker, once the warm weather came though it went away entirely. So I assume that once the cold weather returns so will the noise. Though I'm pretty sure now that it is just the lifters as they pump up with oil and not a rod bearing or anything like that, thanks to this board as I've heard quite a few other owners express the same complaint and everyone's fealings are always that it is the valvetrain. I wouldn't worry about it, my car had about 40,000 miles on it last fall when it started making the noise and now it has 107,000 miles on it and still running very strong!


It isn't the valve train at all. The roller finger follower valve train is pretty quite and the stationary hydraulic lash adjusters are pretty good at holding their oil charge.

Likely the noise is the pistons touching the carbon in the combustion chamber as described. It's worse in cold weather because the piston fit gets a little looser on the cold start (the pistons, being aluminum, shrink slightly with the cold and shrink a little more in winter weather. Pistons do that). The noise is actually the pistons rocking slightly in the cylinder bores due to the piston motion being upset slightly at TDC because the piston is touching the carbon on the head. The noise goes away as the engine warms up as the pistons warm up and expand to normal operating clearances and the carbon contact makes less and less of an impact on the piston motion at TDC.

Quit driving it like a weeny. Floor it occasionally and let it air out to clean the carbon out and the noise will go away. I'll bet you that frequent WOT's to redline will cure the noise on the cold start.

Spyder
09-15-04, 11:57 PM
Hehehe, he called you a weeny! :histeric:

CadiJeff
09-16-04, 12:41 AM
I scared myself yesterday, I did a WOT run and after I stopped at a stop sign it started acting like I had a missing cyl, so I gunned it again and all of a sudden a big dark cloud of exhaust came out of the pipes and the engine quit running rough and it actually sounds more quiet now. I figured that I must have blown a large piece of carbon through and the rough idle was a indigestion(burp), though I suppose that would make the smoke a fart?

Spyder
09-16-04, 12:30 PM
CadiJeff, I did the same thing...I was driving through St. Louis a few weeks after I got my car, and in the second day of a 5000 mile drive, scared the hell out of me when I saw a huge cloud of smoke coming out of the back of my car...but I never saw it again and it ran great the whole rest of the time, guess it was a good thing.

FLEALAMI
09-16-04, 05:27 PM
Anthony,

I followed your suggestion and opened it up twice using your second gear/6000 RPM method and this morning when I started the car.......NO NOISE , SMOOTH AS SILK.
Thanks for the good info. :thumbsup:

Flea

Anthony Cipriano
09-16-04, 10:30 PM
Good deal. Now remember to do this occasionally...

foo
09-16-04, 10:31 PM
So, what happens if I do that procedure 50 times and the noise is still there? I just can't get mine to go away no matter how hard I beat on it. It's just always been there.