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QUESTION:

have water leaking out of the left front part of the exhaust manifold on my 1992 chevy s-10 pickup truck, V6 2.6 engine. could it be a blown gasket or a cracked head. what the best way to determine this? what would be cheaper, a rebuilt engine or a mechanic to repair it?
 

ANSWER:

The best way to find out for sure where it is leaking would be to remove the exhaust manifold and then do a pressure test of the cooling system. Sometimes you will find the leak is coming from something that was not even close to what it looked like in the beginning. If you can even get underneath the truck and do a pressure test on the cooling system, you may find that it even has a freeze plug in the side of the engine block under the manifold that is leaking. Or you may be able to see it better with a small mirror on a long handle. If not, then I would remove the exhaust manifold to take a better look. If the head is cracked, it could let coolant come out around the threads of the bolts that hold the manifold to the head, as these bolt holes go in right next to the water jackets in the head where the coolant circulates. Same if it had a blown gasket, except the coolant could be coming out of the exhaust port for the manifold. A crack between the valve seats of the head would also cause this kind of a leak. If you do determine that the leak is at the head, you will need to remove the head for inspection to see if it is a gasket or a cracked head. Sometimes a crack will only show up under pressure, in that case a machine shop will need to inspect the head and maybe even magnaflux it to find any leaks. If you end up needing help to remove the head, drop me a note. Unless the motor has real high miles on it or other problems, it will be cheaper to repair than to replace.

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