gasket sealer or no gasket sealer?

[rx4ur7]

As was told to me at GM, Porsche and Mazda schools in a perfect world where everything could be machined to tolerance there would be no need for gaskets. In the world of mass production these tolerances really can not be maintained therefor the need for gaskets. Still in all schools sealant is not recommended when using a gasket. Except in very specific applications. If you have cleaned surfaces properly the gasket will work by itself. If a sealing surface has been cleaned by rough scrapping or grinding the old gasket off with power sander, then one may have to use something. In the 40 years of working on motor vehicles I rarely resort to the use of RTV or sealent unless recommended by manufacturer. Mazda does recommend the use of HYLOMAR in a few places. But not water pumps. If you have to use anything use very sparingly. Don't know how may rotaries I have had to replace that have had RTV blocking the cooling passages in rotor housings causing overheat and premature engine failure from overheating.

TitaniumTT does make a good point, I have also come across a few pumps from Mazda in the recent past (FD3S's) that have had clearence issues, never saw one before that. Very uncharacteristic for Mazda in all the years I have worked on them. It was when they changed supplier. I put it to influences outside of Hiroshima that have made them use cheaper parts.