Installation of block heater

[benzboy87]

Any tips on installing a block heater on a '90 420SEL? I am about to do this tonight or sometime this weekend and woud like some input. I already have access to a 19mm allen socket that was fabricated for this purpose. Any hints on removing the plug? I hear it is a ***** to get out. I am flushing out the old coolant (less than 6 mo. old but the local indy put in GREEN coolant) anyway so thought this would be the ideal time to install one. Any danger of damagine the block when taking out the old plug?

[donbryce]

My friend, a retired MB mechanic of over 30 years, once cautioned me that the frost plugs in the old iron blocks can be extremely difficult to remove, and very often end up taking part of the block at the rim out too, making sealing the heater a real pain.
Of course, this was when I was running a 1976 450SE in the Canadian winter, around 1996. Yours isn't that old, and not as likely to be rusted in solidly either.
I have to ask: why would you want to bother with a block heater in Kentucky (the origin of my current '85 380SE BTW)?

[benzboy87]

I am in the mountains and, even though it doesn't get horribly cold in the valleys, temps can vary as much as 20 deg. on top. I also would like to have the luxury of having immediate heat - also, less wear and tear on the engine on startup.

[abe g]

Consider a hose line heater! These available at most auto stores, cut into radiator hose and heat coolant (instead of oil) If youmust have a heater, better than fighting with a rusted in plug! Good luck Abe G

[Cigar Havana]

I had one put in last year into a 1989 420SEL. The mechanic put it in three times before it stopped leaking. He finally used one of those thread sealers, good to 3000 PSI and petroleum products, (available at home depot). The tape did not work on it, he tried twice. If you don't do it right the first time, you'll be draining the coolant on each subsequent try, so may want a little extra on hand.

He used a cold chisel to start the plug turning, when taking the plug out.

[benzboy87]

UPDATE - I installed the block heater in Jan.2005 and have to say that it sure is nice to have immediate heat - especially considering I leave the house most mornings before 6.
I will say that it was as difficult to remove the block plug as everyone would say it would be. I finally had to use an air chisel to get the plug bent enough to actually pull it out. The actual installation of the heater was easy and, so far, no leaks.