The MGA With An Attitude
GASKETS AND SEALANTS - CF-109
At 07:22 PM 4/12/06, Gregory Brown wrote:
>".... do you use any gasket sealant in any of the gaskets?"
Here are a few general rules which seldom vary.
1.) Use no sealant on any gasket which is installed between two machined surfaces.
2.) When installing a gasket for a sheet metal cover, straighten the cover as well as possible first. Thick cork or rubber gaskets should not need any sealant, but if you feel the need to glue the gasket in place for ease of assembly, glue it to the sheet metal cover only. That way when you next remove the cover the gasket comes with the cover, being easiest to work on the bench to remove the gasket for replacement. Also thick pliable gaskets may be reused a few times if they stay stuck to the cover and are not abused.
3.) When installing a relatively thin and generally incompressible gasket for a sheet metal cover (like sheet metal timing cover for instance), straighten the cover as well as possible first. Then apply a moderate layer of bulk filler sealant, such as silicone RTV (Permatex "blue stuff") to the sheet metal cover only, and stick the gasket in place on the cover. Let this set (if necessary) only long enough for the gasket to stay in place during handling. Install the cover and torque all screws gently, finger tight to start. Then tighten screws evenly in repeating sequence until the sealant can be seen to squeeze out a small amount all around the gasket. This is indication that the sealant has filled the joint all around with no remaining gaps. Experience will tell you how little sealant you can use, and any excess may do some harm with no benefit. Then let it set for a longer time, like maybe over night, for the sealant to set up to a pliable but non-flowing condition. Then tighten all screws evenly, enough to assure they are secure and will not vibrate loose to fall out (always assuming the use of lockwashers for a sheet metal cover).
Keep in mind that there is no need to grossly over tighten screws for a simple gasketed cover. It ain't holding the wheels on, just keeping dirt out and oil in. Over tightening cover screws can only serve to warp and distort the cover, which can cause leaks rather than preventing them.
In some cases you may be dealing with threaded holes which may go through into the interior of the housing containing fluid. For the MGA this will include one or two of the studs for the thermostat cover, some water pump bolts, four out of six manifold studs, and possibly some of the top cover and/or shift extension fasteners on the gearbox. For these applications you should apply thread sealant to the male thread before installation to prevent liquid from leaking out around the threads. Such leaks can rust and seize thermostat cover studs and water pump bolts. Leaky manifold studs can dribble oil on the hot exhaust manifold.
But you still don't need any sealant for any gasket other than as used single sided for a sheet metal cover. The only exceptions I know of are as noted in a workshop manual for a specific application, and there are none of those notes for any MG.
Here's hoping that this generic answer will cover all of your specific gaskets for the rest of your life.