Would a 19mm hex socket work to install a block heater?
 

If I went to Sears and bought a 19mm hex key. Would I want like a 1/2" or 3/4" drive. I doubt they would have 3/4" though. Would that be stroing enough or would I want one that is shaped like an 'L'? Also, what has to be removed/disconnected on a w116 to make this work? It is a 617 by the way.
Thanks
David

I remember my mechanic doing this around 1991. I think he had a socket and not just the L wrench. The car was up on the hoist and he had to use an extension to break it loose. I doubt you could successfully do this without the use of a hoist to get the vehicle high enough off the ground to get the proper leverage. Your car is now 10 years older than mine was at the time. The block heater is a nice set up and worked well twice in Jackson Hole Wyoming during ski season. 17 degrees at night.

I will be doing this at my uncle's car dealership up on a lift. He and I were afraid that maybe a 1/2" breaker bar would break. What would you guys suggest to remove from the car/disconnect and would an 'L' wrench hold up to that amount of torque?
Thanks
David

I cut a piece of the Allen wrench off with an angle grinder, that was the appropriate length, and put it in a 19 mm. 3/4" drive socket with a 3/4" drive breaker bar and a pipe "persuader". Kinda... "make your own hex bit", only really sturdy.
(Pretty sure it was 19mm. (Alzheimer's?)) ;

You can use 19mm. Allen and socket or SAE 3/4" Allen and socket since they are ~identical (19mm. equals .748 inches).

Same technique works for making a 1/2" drive 10mm. hex bit for breaking loose rotors from hubs.

Old mechanic's trick
 

Drain coolant, heat plug and surrounding block area with torch, quickly cool the plug with water. Usually the plug will unscrew with your hand.:D I have used this trick for years to remove plugs from truck and equipment blocks.

What would you think about getting the car hot, drain the coolant, then heat the surrounding area with a torch, then cool the plug?

I have a 19mm allen snap on, with a 4 foot breaker bar, and I could not get it out. I just did it when the engine was hot.

old mechanic also ... says.....
 

It is incredibly dangerous to the integrity of your block to try heating it with a torch.
If you really must heat anything just heat the actual plug... this usually squeezes the rust and corrosion ( let cool before trying to take it out ) and makes it possible to get it out....
The block is cast iron... known for needing even heating and cooling in order to avoid cracking....
Many may have thought they actually got the block area hot enough to help them remove it... and may not have been computing the convectional heat loss.... ( ie, they really did not heat it enough to make any difference to the plug ) but thought they did... where actually heating only the small plug has a shot at heat expansion worth trying... and if it happens to be cast iron itself you can easily replace it if it cracks.... unlike the engine block..

Do I need to mention that antiseize should be placed on the threads of whatever goes back into this hole ?

I could not get mine out with a breaker bar, so I choose to leave my plug in because replacing a block is very expensive.

Thanks for reminding me, I still need to put my block heater in my 300CD, it's just been sitting around for the last year, and I havn't got around to installing it.

I have this spray that will help get stuborn bolts and nuts out. I forgot what it is called, but I it sure works great. It helped with breaking loose the drain plugs on the diffs. in the Subaru...

I just bought a 3/4" allen wrench from NAPA about 15 minutes ago. It is HUGE. I asked the guy if it would stand up to 400' pounds and he said definitely. I will just stick a pipe on the end of this and try that. I don't think you could ever just get the plug out with a 1/2" breaker bar. Has anyone ever done this without a lift? When people do use a lift, how long of an extension total do they use?
Thanks
David

As an old guy who has to deal with things like old tractors....
I would like to suggest a picture of mechanical advantage which might work...
Stick something the correct size into the item needing to be broken loose...
Extend with pipe or long enough handle to a spot going towards the front of the car in which access is available straight to the floor.
Use a piece of metal to fit under this extension ( since we are dealing with a right hand thread this end needs to travel UP to turn it the correct direction ).
Then place a hydralic jack under this downtube and wrap duct tape on both ends to keep everything in line until they get under pressure..
Then just pump on the hydralic jack.... Keep fingers out of the way and always wear goggles....

The engine will lift up fairly significantly with the jack technique, so keep an eye on fan shroud, linkage, engine mounts and engine shocks.

Ok, if that becomes a problem think upward use of a slide hammer on the end of the extension.....a quick application of force is preferable... but this is a limited access area....the use of an air hammer on the side of the allen wrench might help also..
If this doesn't work right up front.... make a well to hold a penetrant with aluminum foil and silicone seal... let set overnight and then fill with P'Blaster or something for several days...then start over with force..

Just did mine.

19 mm allen, 1" ratchet, 2' cheater pipe, needed to remove starter and the car is up on stands.

Could not do it with my arms, turned around and put my foot to it. Braced myself with the car and pushed with my foot. It let loose with a nice loud "pop". Pretty simple really. I would not wish to try it with anything less than 1" tools.

Done it twice. Pain in the butt.

6' breaker bar on 3/4" stuff. Landed on my butt once but both times, it finally gave way. Did it in a mechanic's pit that was 6' deep.

Don