: Scratched Wall



coppercitymt
01-30-12, 08:27 PM
Found out that the miss on my 2002 STS is from a scratched wall on them number 3 cyl. It comes in at 120lbs were as the orther ones come in at 130LBS.

Would you think this would effect the motor in terms of it's lifespan?Or become a problem selling it? or buying it?

Ranger
01-30-12, 11:18 PM
How do you know that the cylinder wall is scratched without removing the head and looking at it? How would that happen?

coppercitymt
01-31-12, 12:52 AM
The dealer said they put a cam down the spark plug hole. Don't' know how it happened maybe carbon build up?

Ranger
01-31-12, 10:48 AM
I doubt it is from carbon. Broken ring maybe? :noidea:

Submariner409
01-31-12, 11:09 AM
120 is less than 10% away from the other average of 130 - and all those compression pressures seem a bit low for a Northstar.

I doubt that a scratched cylinder wall would cause a miss - the scratch would have to be so deep that the cylinder had essentially zero compression.

What is your experience with oil consumption in this STS ? If you have a damaged cylinder wall the consumption would be, ummmm....... significant.

Broken ring ^^^ or maybe part of a spark plug electrode or ceramic tip. Not "carbon".

coppercity, Click on my username, open my profile. Two albums in the left column - 6 pages of stuff for our engines, including several of the ignition parts your dealer has been fooling with.

coppercitymt
01-31-12, 01:30 PM
Well yes oil usage has been a problem about 3/4 of a QT in about 500 miles. It was low when I bought it. 3/4 Qt to fill then 500 miles later another 3/4 qt.

That's what made me do some WOT and red-line shifts, clean up some carbon and move those rings around. After that is when the miss started. So maybe the WOT busted a ring?

The dealer said it should not really effect the motor in anyway but from what I know about cars that sounds like BS!

Sounds like I may need to walk away from this deal?




120 is less than 10% away from the other average of 130 - and all those compression pressures seem a bit low for a Northstar.

I doubt that a scratched cylinder wall would cause a miss - the scratch would have to be so deep that the cylinder had essentially zero compression.

What is your experience with oil consumption in this STS ? If you have a damaged cylinder wall the consumption would be, ummmm....... significant.

Broken ring ^^^ or maybe part of a spark plug electrode or ceramic tip. Not "carbon".

coppercity, Click on my username, open my profile. Two albums in the left column - 6 pages of stuff for our engines, including several of the ignition parts your dealer has been fooling with.

Submariner409
01-31-12, 02:00 PM
In your engine, "FULL" is here on the hashmarks:

<= ADD=XXXXXXXXXX = OPERATING RANGE ==============O .

Any higher than that and the Northstar tends to get rid of the excess in a hurry. (Exactly 7.5 quarts with filter puts the oil level right there.)

Go up in the black bar and read the entire Cadillac Technical Archive, especially the articles on Northstar oil consumption and "Occasional full throttle operation is good .............."

Our engine - how many miles on the plugs and boots ? Did you check out the pictures of ignition parts ? Have you checked the individual injector connectors ? Your WOT and redline shifts did not "break a ring" - my car sees that sort of fooling around almost daily (when fully warmed up).

coppercitymt
01-31-12, 02:18 PM
The oil level when I added 3/4 of a qt was right below the 1st X. 3/4 QT put it slightly above halfway.

The car has 64K on it, as far as I know it has nerve had any tuneup ect. Checked out the photos thanks very helpful, also read the things very helpful, so a qt per 1000 miles is not unheard of. Make me feel better!

This tings scares me to work on it, I am pretty good at working on cars, starters alts water pumps carbs fuel tanks tuneups ect are easy to do on older stuff. But this newer stuff like this caddy scares me ;-) I don't even know if I could handle a tune up on one!




In your engine, "FULL" is here on the hashmarks:

<= ADD=XXXXXXXXXX = OPERATING RANGE ==============O .

Any higher than that and the Northstar tends to get rid of the excess in a hurry. (Exactly 7.5 quarts with filter puts the oil level right there.

Go up in the black bar and read the entire Cadillac Technical Archive, especially the articles on Northstar oil consumption and "Occasional full throttle operation is good .............."

Our engine - how many miles on the plugs and boots ? Did you check out the pictures of ignition parts ? Have you checked the individual injector connectors ? Your WOT and redline shifts did not "break a ring" - my car sees that sort of fooling around almost daily (when fully warmed up).

Submariner409
01-31-12, 02:27 PM
The worst part of doing a "tune up" (spark plugs, period) on our cars is the aching back from screwing around over the right (rear) bank of cylinders............and that's not even a problem until after 100,000 miles.

(and the starter is under the intake manifold..................)

vincentm
01-31-12, 04:33 PM
The worst part of doing a "tune up" (spark plugs, period) on our cars is the aching back from screwing around over the right (rear) bank of cylinders............and that's not even a problem until after 100,000 miles.

(and the starter is under the intake manifold..................)

Yup, rear bank plugs can be a pain, but that's mostly due to habing to stretch yourself to reach em, other than that...piece of cake...oh yea, the starter... >.<

00 Deville
01-31-12, 08:18 PM
Yup, rear bank plugs can be a pain, but that's mostly due to habing to stretch yourself to reach em, other than that...piece of cake...

It's a different animal on a 00+... most of them have an air pump relay mounted directly on top of the rear ignition cassette. What a PIA to remove it to gain access to the rear bank.

coppercitymt
02-01-12, 12:40 AM
Talked to a diffrant guy at the dealer today, he did not have such a pretty picture to paint. He said number 3 is only 110PSI and has damage on top the piston as well as the wall. The car also has problems with the ABS Trac. Control and other light right next to it coming on at random.

All told they want over 3000 bucks to fix the problems. Said it has to be ripped down the head to find out what's going on.

My big question is will I do more damage to the motor driving it around like that?

This car is turning in to a nightmare :mad:

maeng9981
02-01-12, 02:21 AM
Has to be ripped down to the head to see what's going on, and the engine has to come out to repair if there is a damage done to the piston/block.

vincentm
02-01-12, 11:40 AM
Talked to a diffrant guy at the dealer today, he did not have such a pretty picture to paint. He said number 3 is only 110PSI and has damage on top the piston as well as the wall. The car also has problems with the ABS Trac. Control and other light right next to it coming on at random.

All told they want over 3000 bucks to fix the problems. Said it has to be ripped down the head to find out what's going on.

My big question is will I do more damage to the motor driving it around like that?

This car is turning in to a nightmare :mad:


I'd park it, If you're brave, subscribe the car to Alldata, and get'er done, engine has to be dropped out the bottom on the cradle, and broken down to the block, get a cherry picker and an engine stand lol

Mark D
02-03-12, 05:00 PM
It is apparent that there is a problem in that one cylinder. But as Sub mentioned, the compression numbers seem a bit low for all cylinders. Still, a static compression test is not all that accurate for diagnosis. A leak-down test should be performed before you really know what you have.
And, even at a static 110 psi, that cylinder should fire, with no hint of a misfire. I would not spend the money to tear the engine down until I know what the problem is. It has yet to be diagnosed correctly, based on what you have posted.
I'm thinking ignition wires, vacuum leak, cam timing. How that would be off is open to conjecture.
Your stated oil consumption is a bit high, but I doubt it's part of your misfire problem.

My '98 Northstar engine in a STS has a steady misfire at idle until it's warm. It has had since we got it ten years ago. I haven't bothered to diagnose it because, a) it proved to be something other than the ordinary or expected issues, so it isn't a simple thing to find. b) I had better things to do with my time. c)The thing puts out full power and gets super gas mileage, so why would I even care until I have nothing else to occupy my time?

In your case, it appears you have a steady misfire at all times. Bummer.


And lastly, these things are not as difficult to work on as they appear at first blush. All you need to do is a) get a service manual for the year and model of your car, and then become familiar with it by doing all the work you are equipped (with tools) to do. You'll find that spaces can be tight, but the basics are little different from working on cars of the distant past. They're just cars.
It is a bit easier if you can score your own GM Tech-2 off ebay. That way you can diagnose much more effectively on electronic issues. The intital tool cost is small with comparison of the repair bills you can rack up over the next ten years of ownership.

On the above mentioned '98 STS, I discovered some damage in cylinder #6 when I took it apart for a head gasket job back in (around) 2004. It had a scored cylinder wall, a ding in the piston top and a ding in the combustion chamber. It appeared to me that a plug might have come apart. I also noted that the head had been off before. Something happened. The car was a pretty good oil burner when we got it. Not as much as your car, but not a lot better. After the head gasket job, the misfire was still there at idle, the oil consumption still the same. But after a few years of good hard driving by my lead footed wife, the oil consumption gradually went down to a very acceptable level of about a quart to 1000 miles. The misfire at cold idle never changed. Recently I did head gaskets on that thing once more. This time I used the studs, and it's fine again. Misfire is still there. Not sure that I care. I'll look for it someday. Right now I have other fish to fry.
Mark D.

NHRATA01
02-07-12, 02:03 PM
I would honestly take it to an independent shop for verification.

And realistically at this point, I would say an independent mechanic could probably find you a salvaged motor and swap it in for the price these guys want to yank the head, and if you really did score the cylinder and break a piston, you'll need a new motor anyway which will probably add to the bill. Just my opinion.