Head Gaskets and Valve Covers

No, if there is coolant in your valve cover it'll be mixed with oil. You blew your head gasket, possibly warped or cracked your head. It may look like coolant is leaking from your valve cover but it's your intake gasket leaking.

A few things you have to look at- How old is the car? Except for the bad head gasket, does the car operate OK? How many miles are on the car?? These are things you have to decide what you will do.

Not very long as it is only an emergency repair. The only fix for a blown head gasket is to replace it.

it will cause the engine to overheat and also coolant to enter the oil system, which will in turn cause wear of the lifters.

No

It is normal to replace them.

It is normal to replace them.

Coolant will enter the combustion chamber and get into the oil pan. This will cause severe wear of internal engine components very quickly.

White smoke from the exhaust especially at startup. Coolant mixed with the oil. A white foamy substance on the underside of the oil fill cap. Loss of coolant with no apparent leak. Engine overheating with possible miss.

Possibly, but it really does not matter because sooner or later you will be pulling over anyway. The white smoke is a indication of coolant entering the combustion chamber due to a cracked head or blown head gasket, and the engine will self-destruct if you keep driving it in this condition.

The ONLY head gasket coolant additive (fix) I can most positively recomend is "blue devil" about a dozen fixed vehicles I've done. Different cases too, some wich let exhaust gases in the coolant system causing accelerated overheating as acceleration increases, and other cases where coolant gets through into combustion, causing loss of coolant and white exhaust smoke. Just make sure you follow the directions exactly as on website. I've put thousands of hard miles on head gaskets fixed with this stuff you will be surprised. I was

The 283 has a larger bore diameter, so use the 283 head gaskets.

No.

Never use sealant for a head gasket! It is used as a quick fix for cracks in the gasket but will not last very long. Safer to get the job done correctly.

Yes, it will start. But know that every minute you run the engine you are doing damage.

it will cause overheating and mess up your engine internal moving parts.

has to be heat resistant.

b cos the injector is very long one and it always gets glued in the cylinder head

design fault (material specs ) in merc they have a tube insert in which injector is inserted and insert will be on the aluminium head

Not unless it is leaking so badly as to get enough oil on the plug wires to short them out.

Call around and get estimates from dealers and qualified independents. it is not going to be cheap for sure but the actual cost depends on where you live and if there was damage done to the engine other than just a blown gasket. The head could be warped or cracked. if you kept driving it then there will be other damage to contend with. Too many variables to proved an accurate answer.

Holts Wonda Weld can be used to seal the head gasket in place of a hot welder. The seal will hold the head gasket together until it can be properly repaired. It is not a permanent solution.