Re: Question about movement of antifreeze in radiator

Posted by Linda_and_Steve on February 01, 1999 at 11:46:47:

In Reply to: Question about movement of antifreeze in radiator posted by Sam on January 31, 1999 at 22:19:33:

Bubbles in the coolant are a good sign of a blown head gasket...however there are some other things that can cause it...(cavitation etc.)...but in the line of bad headgaskets there is a way to tell...if you see bubbles in the radiator take an old sparkplug and screw it into the first cylinder and leave the wire off..start the engine...(she'll run rough)if you still see bubbles but they are fewer there is a good chance the headgasket is blown...if there is no change try the next cylinder...then the next 'till youv'e tried them all. If there is a change (reduction) in the amount of bubbles it's a good chance of a bad gasket. The reason this works so well is that the bubbles are caused by cylinder compression and the cylinder firing if you eliminate the cylinder firing by not having the wire on there will be a reduction in the number of bubbles. The downside here is that it might be a cylinder wall crack..but not often is that the case. The important thing here is to find a problem such as this as soon as possible...since antifreeze corrodes the babbit on the bearings and can cause lower end failure. (And a bad head gasket will get coolant to the oil pan sooner or later) Finally the reason we said an old sparkplug for this test is that the plug will be fouled for sure.

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