Cadillac Repair: Coolant Loss, cylinder head bolts, coolant loss

Question
Mr. Cherniwchan,
On 01/03/07, you answered a question for me regarding coolant loss.  The answer that you gave was helpful. However I forgot to mention that not only was I losing coolant from the expansion tank; the front passenger floors are wet on both sides, but I also am having coolant loss from the bottom of the car.  I've had someone to tell me that they feel as if it may be the intake gasket.  However, I feel as if that is questionable!  Did I mention earlier that I have over 173,000 miles on the original engine.  Getting rid of the car is not optional, being as though Cadillac has cut down on its interior space with its new models.  Any guidance that you can provide will be beneficial.  

Thank you in advance,
Alicia

Answer
Hi Alicia,

       Since you are looseing coolant from under the front of the car it sounds like the radiator cap might not be able to seal propperly to the tank or hold the correct pressure before the valve in the cap opens. If by replaceing the cap the problem hasn't been fixed then you could try replaceing the thermostat...reason being is that it isn't opening enough or at all and pressure is building up.

      Being skeptical about the intake gasket was a good move in my opinion. If you had the 4.1-4.9L engine then the intake would be a common problem area. On the northstar engine the problem seems to be cylinder head bolts that pull the threads out of the block. There might be 1 or 2 to start and after replaceing and torqueing the bolts another one might pop so my recomondation would be to do all the head bolt threads useing a TimeCert or replace the engine.

      To diagnose this as a problem if the coolant starts to bubble out of the expansion tank with-in 5 minuits of a cold start then its probably head gasket or engine time. The other thing to do is go to a bigger parts store like Napa and buy a combustion leak detector. It has a blue liquid that will turn green if exhaust gasses are getting into the cooling system and a test tube and rubber bulb to draw the vapors into the tube. If you haven't already gotten a coolant pressure testor to verify leaks that would still be a good thing to do. Otherwise have a shop do the testing and you can take it from there.

      Let me know if I can be anymore help. Bill