In the case of a damaged head gasket, an engine block sealer might be a cheaper and faster alternative to replacing expensive parts.
How Engine Block Sealer Works
Engine block sealer contains the main ingredient of sodium silicate. Antifreeze in the radiator is temporarily swapped out for engine block sealer. The sealer then fills in the cracks of the gaskets. With the help of engine heat, it dries and hardens into glass, therefore stopping up the leaks that were likely causing over-heating and helping to prevent a blown gasket.
How Effective Is Engine Block Sealer?
Engine block sealer is an effective way to block cracks and stop up leaks where otherwise extremely costly repairs would be needed. Mechanics themselves recommend it to those who don't want to replace gaskets or even the entire engine.
However, engine block sealer should not be considered or used as a permanent fix. Some have attested to the sealer holding for over three months and 2,500 miles. Others have noted that while it works, you may notice your car running a little hotter while idling than it normally would, although well below a level of concern.
Overall, use the engine block sealer as a temporary but effective and cheap fix until you can have a professional take a look at and repair your car.