Tech Tip 12 Sealing Gaskets With Gasket Sealer

January 1st, 2006 by admin


Tech Tip #12

Sealing Gaskets With Gasket Sealer

Obviously the reason for applying a sealer to a gasket is to insure there will be no leaks, Right? However, did you know that the use of the wrong kind of sealer can actually cause the motor to seize up? The almost universal use of silicone sealers as either a gasket by itself or as a coating is not a bad thing. What is a bad thing isundefined the use by unqualified mechanics (read you) in ways it was not meant for and in quantities that are ridiculous.

Lets examine the photo to the right. (“Click” photo for more detail) The red circle shows excess silicone in a critical area, the head oil feed. The blue circle shows a length of dried silicone ready to break off and fall into the crankcase ready to foul the oil pickup, or worse, the oil pump! Also note the use of standard household clear silicone like what would be used on a bathtub! If the silicone blocks this passageway, EVERYTHING above the piston is landfill from lack of oil. Still skeptical? Check out the bearing. Note the cam bearing journal. The red arrow indicates where the aluminum bearing has been worn away from the lack of oil. Care to guess what a complete head, costs?

Now lets look at the silicone. If you see that much silicone squirting out when the head is torqued (Red circle) it don’t take a rocket scientist to realize there will be an equal amount being forced inward (Blue circle). A majority of the squish band of the combustion chamber is filled with silicone seal! (At least this yo-yo used blue automotive silicone seal!)
undefined    So, what can you use that won’t damage a motor if used excessively? 3-Bond 1104 Liquid Gasket. Why? Because it never dries hard like silicone. It is used by the OEM’s for engine assembly. (It is that gray liquid you find on the walls sometimes if it is dribbled during assembly.) The only drawback to using 1104 is the engine surface you are applying it to must be grease free or the stuff will ball up on your finger as you are applying it and you usually can’t find it at the local auto parts or hardware store. Do your motor a favor and stop using that bathtub sealer and use a professional type product for a professional type job.