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.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

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.

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Never a dull moment at Berry Hill Farm.

"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.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

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...

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

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

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References