Head gasket
(→Copper head gaskets) |
(→Head gasket sealants) |
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===Head gasket sealants=== | ===Head gasket sealants=== | ||
| − | + | Current technology OEM and racing head gaskets are designed to be used without additional sealant, however there are cases where head gasket sealants are required or helpful. Head gaskets sealants are specifically designed for the application; due to extremely high pressure within the combustion chamber which must be contained by the combustion seal, generic fluid sealants such as silicone should not be used for head gasket sealing. Unlike RTV silicone, head gasket sealants do not cure, they remain pliable indefinitely thereby allowing the head/gasket/block interface to achieve metal-to-metal contact under the compressive load of the tightened head bolts. Metal-to-metal contact insures a proper combustion seal. Conversely, curing sealants such as RTV silicone can form a 'rubber layer' upon which the head/gasket/block interface are separated allowing combustion pressure to eventually form a leak path to the coolant system or to the outside of the engine. Differential expansion rates of bi-metal engines are also accomodated by use of proper head gasket sealants which will not shear because they do not cure. | |
| + | '''MLS Head Gaskets''' | ||
| + | Sealant use may be required when retrofitting MLS head gaskets to engines which were not originally produced with MLS head gaskets, or when using MLS head gaskets on engines that have not been properly prepared. For proper coolant and oil sealing, MLS head gaskets require surface finishes of 30 RA (Roughness Average) or finer, this is because the elastomeric coating on the sealing surfaces of MLS head gaskets is approximately .001" thick which is too thin to seal leak paths in the peaks and valleys of rougher (RA30+) finishes. | ||
| + | '''Steel Shim Head Gaskets''' | ||
| + | Steel shim head gaskets are exactly what the name implies, simply a thin sheet of embossed steel with no sealers applied. Steel shim gaskets rely on the combination of increased localized pressure from the embossment (stamped ridges) much like MLS head gaskets, with the addition of a user applied sealant to insure liquid tight operation. | ||
| + | '''Standard Copper Head Gaskets''' | ||
| + | Traditional flat copper head gaskets require the use of additional sealant for cooling and/or oil passage sealing. Similar to steel shim gaskets, traditional copper gaskets have no sealants applied. | ||
| − | + | The following products are commonly used for head gasket sealing: | |
| + | *[http://www.scegaskets.com/Shop/Control/Product/fp/vpid/6650081/vpcsid/0/SFV/32777 | ||
*[http://www.dynatexinc.com/catalog.asp Dynatex Hi-Tack Gasket Spray] | *[http://www.dynatexinc.com/catalog.asp Dynatex Hi-Tack Gasket Spray] | ||
*[http://www.hylomar.com/market_served_automotive_oem_3.shtml Hylomar Universal Blue] | *[http://www.hylomar.com/market_served_automotive_oem_3.shtml Hylomar Universal Blue] | ||
*[http://www.permatex.com/products/automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Copper_Spray-A-Gasket_Hi-Temp_Adhesive_Sealant.htm Permatex Copper Spray-A-Gasket Hi-Temp Adhesive Sealant] | *[http://www.permatex.com/products/automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Copper_Spray-A-Gasket_Hi-Temp_Adhesive_Sealant.htm Permatex Copper Spray-A-Gasket Hi-Temp Adhesive Sealant] | ||
| − | *[http://permatex.com/products/automotive/automotive_gasketing/gasket_sealants.htm various Permatex gasket sealants] | + | *[http://permatex.com/products/automotive/automotive_gasketing/gasket_sealants.htm various Permatex gasket sealants] |
===Head gasket repair additives=== | ===Head gasket repair additives=== | ||
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