Expert: Rob Painter - 1/23/2011

Question
i had my heads professionaly checked n machined and replaced the gaskets myself. after i put everything back together, and checked the electrical connections and distributer the car turns over but wont start.

Answer
Hello,

it sounds like you are repairing an aluminum Cadillac engine that was over heated.

Here are the problems I have answering your question: You did not state the year of your STS.

Also, without being at the car, I have no idea as to what is the problem since the engine has been disassembled and reassembled. Is it a compression issue? Is it a fuel delivery issue? Is it a spark issue?

Is there a harness not connected? Is there a sensor broken? The primary questions are is it a fuel delivery or a spark problem?

You can generally tell if the fuel pump is working by putting the ignition in the ON position, removing the fuel filler cap and listening for a hum. That tells you the fuel pump is running.

As for spark if you don't have the diagnostic equipment, the old fashioned way to check this, is to remove a plug, Attach it to a plug wire and have someone crank the engine for a couple of seconds. You should see a bright blue spark at the end. I recommend placing the wire and plug close to the head, so you don't get jolted, finding out the hard way that you had a bad wire in the area where you would have been holding it.

If you don't have spark, there may be a harness hidden some place that you did not connect.

It's always difficult answering questions like this because all aspects of the original design have been altered. So many people blame their starting problems on the factory so-called "anti-theft" system and 99% of the time, it was something else.

Is the distributor in properly? The list of questions to your situation could become overwhelming.
This would call into question timing, which would allow the engine to crank and not start.

Depending on the year of your STS, if it has the VATS with the resistor chip in the key, the system disables cranking all together and that tells you for sure it is not an anti-theft issue you are dealing with.

What you need to do is tell me the year of the STS first. You need to determine if you have spark and fuel and then get back to me.

I am working in the dark here and don't know what you did and did not connect properly. I am not at the  car and my answers depend directly on what you tell me.

Once running, you need to find the over heating cause as well because once it begins to over heat again, you will be changing head gaskets again.