REAR MAIN PAIN We are still getting lots of calls on rear main seal leaks on LS engines after rebuilds. We suggest engine builders install the rear seal with the lip facing the crankshaft, like all other engines, regardless of installation instructions. This change in...

SUBARU HEAD GASKET TECH The EJ series 2.5l boxer engine has been powering many Subaru vehicles since 1996. With many different variations, they all share the potential for developing head gasket leaks. O.E.M. gaskets were composite or early generation MLS designs,...

CAP-ILLARY SEAL The screw on caps for many sealants do nothing to prevent the sealant from drying in the nozzle. I used to hate digging out the dried Sealant. Not anymore. My co-worker told me to pack a 1/4 of the nozzle with lube. If no air gets to the sealant, it...

SEALING HEAD BOLTS RIGHT We have always sealed the head bolts that go to water with a Teflon sealer of some kind, but we still had one that leaked from time to time. So when I saw an ad for a new and improved Teflon Sealer, I called the company. The engineer that I...

FLATNESS AND SURFACE FINISH Cylinder head and block flatness and surface finish are critical to proper head gasket sealing. The following general specifications cover both gasoline and diesel engines. Since bolt spacing, location of oil and water holes, pressures,...

RETHINKING OEM EXHAUST FLANGE GASKETS You want to seal that flange with an OE MLS gasket? Good luck! -- The same conditions now exist in exhaust flange technology as when the first MLS head gaskets were being replaced under repair conditions. OEM MLS exhaust flange...