My daughter's car had a check engine light on and was overheating. We had it towed to a mechanic and he did the block test with the vapors. The mechanic said the blue stuff turned yellow immediately and wants about $1300 for repair which includes gasket kit, bolts, water pump (not sure if that is necessary), spark plugs, wires, thermostat, coolant etc.

I have free towing with my insurance. Talked to another shop that we have used before and if the problem is determined to be the same then the price to fix it is about the same. Question really is: should I get a second opinion on this issue?

3 Answers 3


It is ALWAYS good to get a second opinion. I would highly recommend taking it to another shop and have them tell you what they think it is even if you believe the first shop to be right.

That being said, there are a couple of things you can do at home to try and diagnose a head gasket problem yourself. Look to see if white smoke is coming out of the tailpipe while the car is running, check the oil to see if it's a milky color instead of the usual oil color, look for leaks around the head gasket area. You could also pull the thermostat out and run the vehicle without it. If the car overheats still with the thermostat out or you can see bubbles in the coolant overflow tank then you more than likely have a bad head gasket.

I'm not sure why the spark plug wires would be replaced with a head gasket job. The water pump doesn't necessarily have to be replaced either if it's only the head gasket that's bad although the high temps may have affected it. All in all though, get a second opinion from a trusted mechanic.


Wouldn't hurt to get a second opinion. However, be careful if you try diagnosing yourself. If coolant is leaking into one of the cylinders and you try starting the car you could hydro-lock the engine and bend a connecting rod which is obviously more money to fix. Before turning over the engine, pull the spark plugs out and turn the engine over by hand before using the starter. If there is coolant on top of a piston it will be forced out the spark plug hole slowly...and will be positive confirmation you need a head gasket at minimum, possibly a cracked head as well.


Texas Ranger is right. If your mechanic has had blue turn to yellow in the chemical sniff test over the radiator opening, this is detecting carbon monoxide in your daughters car coolant. This means that cylinder combustion gasses are entering the engine water jacket, generally through a head gasket failure of sorts. My advice for positive diagnosis is to remove all spark plugs and pressurise the radiator (cooling system) to around 18 pounds per square inch with a good radiator pressure tester. Leave this overnight and in the morning crank over the engine as if to start. You will see a jet of water fly out of the offending cylinder if the head gasket has failed, from here it is just a financial problem, not a mechanical one.

Cheers Hutch

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