: Cylinder rings blown on 18 thousand miles??? (cylinder nr 8 totally w/o compression)



Mustalintu
03-27-05, 07:55 AM
:banghead:

I'm confused!! Can it really be so that my STS yearmod. 2000 with only about 18 tousand miles has blown the cylinder rings on cylinder nr 8??

There is full compression on all other cylinders, expect for nr 8 that shows no compression value at all.

So my question to you Northstar engine experts:

Is it most likely cylinder rings, hole in piston or bended / stuck valves that causes the lost of compression??

The spark plug was OK, only very dirty because of unburned gasoline + oil rests the gasoline had already been dissolving from the cylinder walls?

Could someone also give instructions where to start?

I#m a brand new member of your society and also a brand new cadillac owner....unfortunately this relationship started in a odd way.....

Playdrv4me
03-27-05, 07:06 PM
Welcome to the Forum! :welcome:

Sorry to hear your misfortune, that is definitely odd behavior for a car with so few miles. May I ask why the miles are so low for a 2000? There could be more to the story than is evident.

I went ahead and moved your thread to the appropriate section as well.

Thanks!
Ian.

91TexasSeville
03-27-05, 11:44 PM
The rings may not be "blown"
What may have happened (common) is due to low speed infrequent driving, the compression ring froze on #8 piston. Sometimes upperend lube injected directly into the spark plug hole will help to "unfreeze" the rings. Allow it to sit overnight, then retest for compression. Give it a few shots (attempts) before you open-er-up.

Mustalintu
03-28-05, 04:06 AM
The rings may not be "blown"
What may have happened (common) is due to low speed infrequent driving, the compression ring froze on #8 piston. Sometimes upperend lube injected directly into the spark plug hole will help to "unfreeze" the rings. Allow it to sit overnight, then retest for compression. Give it a few shots (attempts) before you open-er-up.

Hello 91TexasSeville!

Hopefully you are right! This car was previously owned by an older man that was using it very unfrequently....sometimes it stayed in underground garage unused for weeks. So this may well be the case. Do someone have a picture of the Northstar piston so I could see what kind and how many piston rings it has? Why would this common problem affect in only one cylinder? Is the lubrication somehow weaker in cylinder 8 as in the other ones? This car have had multigrade motor oil. If I get this problem solved without tearing the engine down do you have any recommendations for proper oil?