: 4.6l N* knocks in cold weather, but quiets after operating temp is reached.



texas177
01-01-09, 03:54 PM
I just bought a 2000 Deville, interior and exterior is immaculate. It had 104,000 miles when i bought it. A week later the temp dropped and I heard a knocking sound from the engine compartment. After the engine reached operating temp the sound faded. Now that i heard the noise i cant help but notice it. I am very familiar with ford engines, but this is my first Northstar. I took the car to Midas and had an oil change done. The car took 8 quarts of Shell 30w, after this i drove the car to Texas. The car drove good but i heard the sound in the mornings. The car has been good it only used 80 dollars of gas on a 1300 mile trip and still left half a gas tank. Please guys any advice will be appreciated.

Ranger
01-01-09, 04:38 PM
First off, it only takes 7.5 qts. (I put 7 at oil changes).

Do a search for "cold carbon rap". Then take it out and drive it like you stole it. Read up on "Full Throttle.........." in the Technical Archives at the top left of this page.

Submariner409
01-01-09, 05:44 PM
Yeah that ^^^^^ and your car uses 5W-30 oil, either dino or synthetic, whatever floats your boat, as Ranger said, 7.5 quarts MAX.

Go up to the Cadillac Technical Archive in the black bar ^^^ and read the whole thing, particularly "Occasional full throttle is good for your engine".

Quite a few engine changes at the start of the 2000 year.......do some homework in here and in Deville/Seville. Read up on how to pull your own Diagnostic Trouble Codes from the car's onboard system: you don't need an aftermarket scanner - too generic and miss some codes. Look on the sticker under the spare tire cover and enter all the 3-character codes into www.cadillacfaq.com/rpo/index.php (http://www.cadillacfaq.com/rpo/index.php) to find out what's in your car. Look at the driver's door stickers to find out the build date and tire size/speed rating.

If you get antsy to check the transmission fluid, it must be done with the engine hot running in P.....the transmission is a dry sump unit and will show NO oil on the dipstick with the engine off.

Welcome Aboard !!!

texas177
01-01-09, 06:15 PM
Thanks Ranger I also googled Cold Carbon rap, and sounds consistent with my car. I will try some WOT tonight when the roads clear up, but is there some additive that can help clean the cc. Please advise.

Ranger
01-01-09, 06:55 PM
Yes, a heavy right foot. Give it a regular dose of WOT once a month or so. The more the better. That's all she needs. No snake oil.

Necrosan
01-02-09, 06:05 AM
Seafoam worked great on my Eldorado and my GFs Lincoln Mark VIII.
The DIC on both cars reported gas mileage increases of up to 4 MPG.
Also seemed to make the Eldo run better at initial turn on.

texas177
01-02-09, 09:51 PM
Well guys I did some hard accelerations in the past day. Aside from enjoying some WOT, I did get to hear sound last a little less during cold start up. My oil change is due already, and I would like some suggestions on what brand and weight. Also is Marvels mystery oil any good? I tried Lucas but it didn't do much a difference, please advise.

Ranger
01-02-09, 10:40 PM
The owners manual recommends 5W30. I still use 10W30. Marvel Mystery oil has a purpose, but not much any more with todays oils. It's basically a penetrating oil as I recall and will thin down you oil. It was very useful years ago for freeing up sticky lifters, but that rarely happens with todays oils. Forget it.

There is a decarbonizing procedure where you put Techron (I think) in the cylinders and let it soak for a few hours. Then suck it out, change the oil, take it out and run it, then change the oil again. Since it is improving, maybe you just need to beat on her a little more.

SPreston2001
01-04-09, 02:25 PM
Yeah do a few more WOT and she will purr like a kitten. You can use seafoam if you wanna clear it up faster and experience the joy of the cloud of white smoke that will pour out your exhaust!! I took the oppurtunity yesterday to let my baby stretch her legs and opened her up to 110mph on the highway!! Before you guys start ranting about how dangerous it is, we had some great weather with no traffic on a nice 5 lane stretch of highway. The only thing I was indangering was my wallet if the man were to catch me!! :burn:

stoveguyy
01-04-09, 10:15 PM
110 sounds like fun but how about just staying in 3rd gear? or even 2nd. that will rev the motor and keep your speed down. its like the joke where the guy got pulled over by a cop and said his alternator was dying so he had to drive fast to keep the motor spinning so the headlights would work. try 2nd gear. duh.

SPreston2001
01-05-09, 01:04 AM
Well when I was doing 110, I was doing it more for fun and not so much trying to do a WOT. When I do my WOTs I do leave it in second and take it up to 70-75mph.

codewize
01-05-09, 08:15 AM
As far as I'm concerned I think a certain amount of knock is pretty normal for these engines in the cold.

I can assure you I don't have carbon buildup and my car knocks a little in the cold weather until she's warmed up.

STSj90
01-05-09, 08:46 AM
Well, i cant say that myne does it. (never really payed attention tho) Ill listen out for it today. Although, i do alot of WOT's. lol Everyday. I never see carbon fly out of the tips. Even in 1 taking off from a dead stop. Its probly because i dont allow carbon build up. Heavy foot FTW! N* FTMFW!!!

:thumbsup:

98eldorado-lee
01-05-09, 09:04 AM
As far as I'm concerned I think a certain amount of knock is pretty normal for these engines in the cold.

I can assure you I don't have carbon buildup and my car knocks a little in the cold weather until she's warmed up.

I agree, if it's only for about 30 seconds or so.

Ranger
01-05-09, 06:12 PM
110 sounds like fun but how about just staying in 3rd gear? or even 2nd. that will rev the motor and keep your speed down. its like the joke where the guy got pulled over by a cop and said his alternator was dying so he had to drive fast to keep the motor spinning so the headlights would work. try 2nd gear. duh.
It's not JUST the high RPM's that clean out the cylinders. It's also the high pressures and temps of WOT and the high engine vacuum on deceleration as well as ring flutter that breaks up any carbon on the rings and keeps them free.

codewize
01-05-09, 07:59 PM
Just ramrodding the car doesn't do it. The WOT is a specific procedure of which the letdown or engine braking is important, as Ranger mentioned.

Mine knocks until the car is thoroughly up to temp and has been driven for a bit.

The soot you see every time you floor it isn't carbon.; That's oil that pools and gets sucked in during hi RPM.

tateos
01-09-09, 07:12 PM
Just ramrodding the car doesn't do it. The WOT is a specific procedure of which the letdown or engine braking is important, as Ranger mentioned.

Mine knocks until the car is thoroughly up to temp and has been driven for a bit.

The soot you see every time you floor it isn't carbon.; That's oil that pools and gets sucked in during hi RPM.

Very cool insight - where does it pool - in the intake manifold?

Ranger
01-09-09, 07:44 PM
It should be carbon and rust from the exhaust system. There should not be any oil "pooling" in the manifold.

codewize
01-09-09, 09:21 PM
A little birdy on this site once told me that. Yes, he says oil can pool in the intake, especially if there's a small leak. The guess was that most people who think they're blowing carbon out are usually sucking this pooled oil in and burning it.

I'm not sure myself but that's what I'm told.

Ranger
01-09-09, 09:50 PM
I seem to recall that, but if it where oil it would be bluish smoke rather than black, no?

SupRNatural
01-10-09, 08:33 AM
It should be carbon and rust from the exhaust system. There should not be any oil "pooling" in the manifold.

Isn't the exhaust stainless?:confused:

codewize
01-10-09, 12:45 PM
*SHRUG* I suppose you're right. Who knows at this point. We've heard so many things from so many people.


I seem to recall that, but if it where oil it would be bluish smoke rather than black, no?

Ranger
01-10-09, 01:14 PM
Isn't the exhaust stainless?:confused:

I'm not sure, but I would doubt that the entire thing is (muffler & CAT). What I said was straight from our old Guru, but I wouldn't think there would be too much rust anyway.

codewize
01-10-09, 09:51 PM
As far as I know the entire exhaust is stainless and has been for years. I think it used to be an option, maybe in the late 70's and early 80's but I'm pretty sure after that era, they're 100% stainless.

I know my Brougham is because I just replaced the muffler and cat. at 200,000 miles. Neither was rotted on the outside but obviously things don't last for ever.

Ranger
01-10-09, 09:59 PM
Thanks for clearing that up Code.

Submariner409
01-11-09, 01:03 PM
My 2002 OEM system is all stainless, but the spot weld process destroys the protective oxide layer and causes rust spots. Take a look at the joint welds for starters..........my CORSA is mirror-bright after 2.25 years.

codewize
01-11-09, 01:46 PM
Sub; did you weld or clamp your Corsa?

Submariner409
01-11-09, 03:35 PM
Clamped.......The whole thing was anti-seized and torqued according to the Torco clamp specs and has not moved or shifted one iota. When we did the install I marked all the joints with black Magic Marker and none show any movement. Luckily my neighbor, Charlie the Transmission Man, has 3 frame hoists so I have unlimited access to easy inspection/work lifts. I did use 4 small s/s hose clamps to center the system by restricting muffler hanger rod side-to-side movement in the rubber hanger cookies.

texas177
01-12-09, 05:18 PM
Guys,

I have not been able to quiet down this car. It still makes the sound and I don't think more WOT's will help any. I have done my homework and think the GM TEC will help. This i my last resort i can't seem to find this at any part store. Any leads will help.

Ranger
01-12-09, 05:27 PM
Dealer would have it for sure.

texas177
01-12-09, 05:53 PM
Ranger,


To tell you the truth I didn't run this Caddy hard I was afraid of breaking something. You know the temp here is getting colder every day and it seems to be lasting longer. It takes about 15 minutes to reach full temp @ 32 degrees. And i hear this sound all fifteen minutes. Also is this something Cadillac is aware of. For example if I take them the car would they say the car has excessive carbon build up. I mean for all I know this car might have never been run hard. It 100.000 miles and its a 2000 model. Im the 2nd owner. Please advise.

Ranger
01-12-09, 06:03 PM
Yeah, they are aware and have the decarbonizing procedure for that if that is what it is. It is not real common though on a 2000+, but if it has never been run hard, who knows.

codewize
01-12-09, 09:29 PM
You're totally safe running a healthy N* hard. That's what they're designed for. Believe it or not they're a real hi performance engine, not a wanna be.

By design they're just made to run. Seriously. As long as there are no known mechanical defects don't be afraid to drive it.

raysteen
01-13-09, 11:27 PM
Just a suggestion, check out Ryno Products BG 44K. I have listened to a call in talk program for years and heard many testimonials for the product. I have been using it every 20K or so on the cars I have owned. I put a can in my '05 Deville a few days after purchasing it. Nothing wrong, just preventative. Costs a little over $20 a can....believe it is a consentrated Techron. Sold only thru repair shops, but if you have a Midas....they sell it. Google Ryno Products and you can check them out. My 2 cents worth.
Ray

raysteen
01-13-09, 11:38 PM
Sorry about that, but Ryno is the local....try: http://www.bgfindashop.com/44K.htm

tman2093
01-15-09, 01:59 PM
slightly off topic, but it was mentioned earlier, someone told the OP to use 5w30 in leiu of 10w30. My oil cap, and owners manual on a 1999 northstar says 10w30. Was the change toi 5w30 related to the other changes that happened to the 2000 northstar changes? Mine ticks as though a lifter is dry (I know, its not a pushrod engine, but thats the sound).

Submariner409
01-15-09, 02:49 PM
2000 and + Northstars use 5W-30 oil. 2000 was the change to roller cam followers and a few other tolerance changes to allow the use of the 5W- oils in order to increase cold flow characteristics.