A cracked engine block is extremely rare. It is typically caused by no antifreeze in the coolant, and the water froze. Other than that, leaking cylinder head gaskets are real common. We always worry about a cracked cylinder head, but even those are very rare.
If you do not want to run the engine, you can perform a cylinder leakage test. That involves removing the spark plugs, placing one piston at top-dead-center on the compression stroke, then compressed air is pumped in through the tester. The percentage of leakage is shown on the tester, but the more informative test is you can listen and look in four places to determine the cause of the excessive leakage.
Hissing at the tail pipe is caused by a leaking exhaust valve.
Hissing at the "oil" cap or dip stick tube is caused by leaking piston rings.
Hissing at the throttle body is caused by a leaking intake valve.
A steady stream of tiny bubbles in the radiator indicates a leaking head gasket.
You can also add a small bottle of dark purple dye to the coolant, then check a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Since most head gasket leaks involve coolant getting into the cylinder, this is a good test for identifying the mysterious loss of coolant when there are no obvious leaks. The dye will show up inside the tail pipe. Of course you have to run the engine long enough for the dye to get to the cylinder.
Auto parts stores will have the dye for the fluid being tested, and those that rent or borrow tools should have a black light. If they have a cylinder leakage tester, ask if they have a whistle to go with it. You screw that into the test hose, then finding top-dead-center on the compression stroke becomes real easy by just rotating the crankshaft by hand.
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Sunday, September 10th, 2017 AT 7:12 PM
