Sizzling block heater...
 

On my 300 the block heater is silent but works quite well but on my 240 I can hear it sizzling (probably boiling) the water.

Is this considered normal? I know that on a friends big pickup he says he can hear his but I am wonderin if this is what caused my head gasket to go out.
it was right over the block heater where it began leaking.

SWMBOs 300D does this same thing.

Most immersion heaters I've come across (teacup heaters, water heaters etc) do the same thing.

IMHO it's nothing to worry about.

"but I am wonderin if this is what caused my head gasket to go out"
Did you weld your radiator cap to the radiator ? If not, then you are in good shape.. they just make noise...

That would be quite a trick, on a plastic tank radiator. :D

JB Weld baby
 

The solution for all those leaks...

I glued 'er down so that I wouldn't have to worry about checking fluid levels... It's worked so well I thought I might try it with the throttle too since that seems to the normal position...:D

Hey, that gives me an idea for my cruise control. A piece of string and a clothespin. Yeah, this might work.