Cadillac Repair: coolant low light, head bolts, coolant system

Question
QUESTION: I have a 99 cadillac sls. I had to have the water pump replaced this summer. After that it has periodically had the low coolant light come on.  I have taken it back to the garage many times to look into this issue. They have put the coolant system under pressure and have found no leaks.  My nephew who is a mechanci suggested putting pellets in to to stop any leaks. Now my light is on again.  There is white smoke that comes out of my exhaust but not all the time?  Any suggestions?

ANSWER: WHITE SMOKE is a classic sign of faulty head gaskets of which this engine is famous for. What has happened is that the steel head bolts have stretched the threads within the aluminum engine block causing the head bolts to become loose thus causing small leaks in the head gaskets.

There is a manufacturers factory service bulletin addressing this problem.

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QUESTION: Where would I find the service bulletin addressing this?

Answer
You would need to contact your local Cadillac dealer.

However, I can tell you what your problem IS and the fix for it.

What you have is stretched aluminum threads in the engine block due to the steel head bolts. This IS a very well known common problem with this engine.

To fix it, You will need to remove both heads from the engine, Drill out the bolt hole threads in the engine block and instal heli-coils in the engine block. You will then need to install larger head bolts and replace the head gaskets to fix the problem.