White exhaust smoke, 1997 Cadillac STS

  • 1 POST
  • V8
  • FWD
  • 70,000 MILES

I have white smoke coming out of the exhaust on my '97 Cadillac STS, mileage: 71,000. The engine also sounds like it has a "miss."I suspect coolant is entering the cylinders. What would I expect to pay for repair? I'm not sure if it's a problem with the head gasket or cylinder head.

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Saturday, February 19th, 2011 AT 7:02 PM

1 Reply

  • 4,228 POSTS

Most often the problem lies in the head bolt threads in the block. They fail and the end result is leaking head gaskets due to lost clamping force. To do the job correctly would involve both heads removed and all bolt holes having new inserts installed. This does employ special tools and procedures, and the quality of the repair lies in the integrity of the person performing it. As a ballpark figure, I would estimate you around 3000 to 3500 for the repair. You have options of replacement motors that may decrease the total some. Here is some things to consider. An engine from a salvage yard may appeal, but it may also have the original aluminum threads, and experience the same condition at some time, maybe even at first start. There is no visual confirmation that the repair has been performed, unless some teardown is performed. A crate motor probably won't have upgraded threads, but it will last longer and have a warranty. The newer generation of Northstar engines had an increase in the thread pitch, providing more metal to, and increasing the strength of the head bolt holes. I am not sure if this design is integrated into remanufacturing service replacement engines or not. As far as repair, if it is done right, it should last the remaining life of the vehicle.

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Sunday, February 20th, 2011 AT 9:19 PM

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