This answer varies by vehicle type, so please be more specific.
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There are many gaskets on any car engine. If you are asking about head gaskets, they are between the cylinder head(s) and the engine block. The cylinder head is under the valve cover. --------------
Silicone spray.
Yes.
yes, their sucking air, 65;
you mean like on a car? Probably not a seal exactly. But i know you can get gasket material to make gaskets from many auto parts stores.
The year, engine size and if it is the intake manifold or an exhaust manifold gaskets would help.
There are a few gaskets on a car:- Cylinder Head, Water Pump, Inlet Manifold, Exhaust Manifold, Sump Cover,Thermostat Housing,Transmission Sump,Tappet Cover,Valley cover,Side Cover,Sump Plug,Differential Sump Plug, Transmission Sump Plug, Oil Filter, Oil Pump,Fuel Pump, I'm sure there are more but these will get you started Also door gaskets and window gaskets.
They have two.
You have to check the fuel pump and the carburetor. (mainly gaskets)
Water is in your engine. Check intake and head gaskets.
check your radiator hoses and change gaskets