First time replacing a head gasket in the engine of a 80's (ish) Toyota Hiace.
I have the replacement gasket all ready to go, but do I need anything else to go on it? Some of the older models needed "Gasket Goo" to seal any possible holes in the gasket before we bolt it back up again?
If you look at the gasket you have: Is it shiny and lacquered? If the gasket is lacquered, you already have the sealant on it. The sealant/lacquer acts on engine temperature and the pressure between the head and block when tightening it down. If there is no lacquer, then you will find it good practice to apply a coating of 'thin' gasket sealing fluid. Sealant for head gaskets usually have the viscosity of an oil. Gasket Goo, whilst not familiar to me, sounds too thick for a head gasket.
Almost all head gaskets I have ever seen DO NOT USE ANY TYPE OF EXTRA SEALANT. I would highly suggest you DO NOT add any separate ANYTHING on the head gasket. Chances are it will spring a leak. Head gaskets are designed to to be a consistent thickness. If you apply anything to them, there is no way for you to humanly get that thickness even. It will be thicker in some areas than in others. When machining a head, it is measured in thousandths of an inch to ensure it is flat. By applying any type of sealant, you will promote warpage.
The only time I have ever seen where it is needed is on some aftermarket head gaskets in high performance applications which would usually be multi-layered metal ones. These might need a copper based spray which will help the metal on metal sealing.
With all this said, if you have instructions telling to use some sort of sealant, then by all means, do that. I would assume, though, that if you had instructions telling you to do so, you would not have come here asking this question.
You should follow the manufacturer's service recommendations for replacing the head gasket. The service manual should specify which additional sealant to use on the gasket, if any.
