THE Definitive Block Heater Coolant Plug Removal Thread
 

<Long>

After much research, and buoyed by my second success at removal of The Defiant Coolant Plug, I am attempting to record how I THINK it works; what worked for me; and what didn't work.

I hope someone else will find it useful.

Also, I'm attempting a third removal next week. The first two were with the engine out; but in the process, I've developed a method and tooling that I believe can work reasonably well, and safely, with the engine still in place.

At the end of the effort, and since I may never have to perform this task again, I am planning to loan out the tools that I built to make the task easier.

My first attempt was on a 616; removed from the car with around 240K. It spent much of its life in the northeast, where the salt baths gave it some "extra bite", I think.

I was successful in removing that plug, first building a tool for turning the 19mm hex:
http://franklynb.home.mindspring.com...MAGE_010-m.jpg

http://franklynb.home.mindspring.com...MAGE_012-m.jpg

This tool is made from an old 13/16" spark plug socket that happened to have a slightly undersized 3/4" hex on its nose, for wrenching. Since it fit in the hex of the coolant plug snugly, I decided to weld it to a 1/2" drive x 13mm impact socket. I selected this socket because its one I never use, as I also have a 3/8" air hammer. It had a nice OD taper on the nose which I inserted into the 13/16" hex, allowing it to be easily tacked dead straight.

It will become clear that the obsession with tool straightness was necessary.
I expected to put some bending load on my home-brewed "Allen" bit. I had no idea how important that criteria would become.

My "zero point" was with this tool powered by a brand new 850 ft-lb air hammer, running at around 600 ft-lb "rated load" -- for 1/2 an hour.

NO LOVE. Didn't budge. I was disappointed, but decided that I really wanted factory pre-heating; as well, I had already purchased the OEM 400W heater, which is a beautiful piece of solid brass -- if you've never seen one. Cheap at $87.

My "first trial" on the 616 used a 3/4" "slider" style breaker bar which is 24" long adapted down to the 1/2" socket drive. This is by plan: IF I snap something along the way, I'd like it to be the adapter, which is the least expensive part. Using a 3/4" socket would have added 2-1/2X the torque capacity at that connection, which would have <perhaps> broken my home-brewed tool, first. At least, that was my thinking at the time.

The 3/4" breaker bar fits neatly inside a piece of schedule 80 hydraulic service tubing, which is 1-1/4" OD and 1/4" wall thick. I use a 2' long chunk of this tube to extend the breaker.

So, first trial, with a 3-1/2' long breaker bar: NO LOVE. Plug didn't budge.

I decided to heat it, with this thinking:

A long time ago, I worked as a "production engineer" at Warner & Swasey, a machine tool company. As part of our regular practice, we seasoned cast iron beds in the "outback" of the factory, in Cleveland, OH -- for up to two years, and as little as 6 months when machine orders were cooking.

As a result, I've seen a few "workarounds" for cast iron on steel rusting problems. We also did refurbishments.

One of the "tricks" I learned was to heat a plug as hard as practical, and then remove it "hot". The thinking was, and is: the plug heats up, and transfers heat to the body of the receiver -- in this case the engine block. Since the receiver is cast iron, the heat migrates away from the hole pretty quickly, but the plug actually FORCES the hole to expand.

When you remove the heat, the cast iron "quenches" the plug in a big hurry, soaking the heat up. The hole "releases" from the plug as it shrinks. This condition persists for a short period, until the hole starts to shrink back in on the plug, and he plug decelerates its cooling rate.

The question for MB blocks is: how hot is "hot enough" to get this release?

I finally got the first plug out with a 6' long "extender" tube on my 3-1/2' bar, for a total torque arm of around 7'. Against this arm, i applied my 180# in a sort of "hammer" mode -- jumping off the ground. and pushing down on the bar.

I also clamped a propane torch to the block and left it running for about 1/2 hour.
http://franklynb.home.mindspring.com...MAGE_009-m.jpg

<This picture is actually on the 617, as some will notice.>

S-L-O-O-O-W-L-Y the plug started to back out, finally yielding!

Needless to say, using a 7' long bar while the block is in the car is more than a bit cumbersome. But, the process gave me hope that I could find a design of tool that would work for installing one of the finest block heaters ever offered on this planet!

ON to "trial #2", where I break, and improve the design of the "home brewed" coolant plug remover. And figure out how to remove it with a "regular" length breaker bar!

--frankb

This is interesting. I once disassembled about 10 cast iron radiators whose sections where screwed together with threaded nipples that had been in place for nearly 100yrs. My experience with those radiators me develop my own procedure for the block heater--install a lower radiator hose heater.:D

I had heard that these plugs were a PITA to remove, and some say the block can crack trying to remove them.

I had my indy put one in a few years ago, I didn`t ask, and he didn`t say how hard it was. I just paid him.

The one I have installed now came with the new engine. The plug came right out. not sure how metric Motors goes about removing them from old engines they rebuild.

this is a nice write up you did,

Charlie

Let us know how it goes with the motor in. By that time I'll have the lower hose heater in. (While my block heater sets on my work bench, still in the original container):(

Trial #2: Also Know As "Heat IS Your Best Friend!"
 

Trial #2: Also Know As "Heat IS Your Best Friend!"

And I believe they might be right!

Having acquired a tired 257K 300D, which I drove from Arizona to Milwaukee after a cursory inspection and a few minor repairs; AND a spare 617.912 engine with 2 degrees of stretch in the chain, but an apparent leaking head gasket:

I decided to chase that vaunted 500 psi "spec compression" mark by rebuilding the leaking, but "younger" engine. Since I'm a fan of block heaters, this gave me a chance to check my "CPR" <coolant plug removal> setup and method one more time, before the ultimate challenge:

http://franklynb.home.mindspring.com...dsc01098-m.jpg

OK. Since its NOT a turbo, as evidenced by the lack of plumbing when stripped of manifolds and starter: its not the ULTIMATE challenge. But,
if I do the "right design" of tool, I think, my setup will also be capable of accessing the plug for turbo-diesels. Ideally, with the turbo and its plumbing still in the car. Ideally.

By the end of the weekend, I hope to remove this plug, using the tool in this orientation:

http://franklynb.home.mindspring.com...dsc01103-m.jpg

.. using the knowledge gained, and some re-design from Trial #2, the subject of this thread extension. <This is an EGR car. Just look at that gook! A power wash is in order. We just need one mild day, so that i don't end up with an ice puddle in the unheated shop bay.>

While my Trial #1 setup proved adequate, there were two things I wanted to improve:

1) use a shorter bar. Certainly less than my 6' long tube extension.

The tool setup is shown below:
http://franklynb.home.mindspring.com...dsc01090-m.jpg

This shot shows the funky gas weld between the two sockets, which is actually a repair, from my effort to:

2) "harden" the tool setup such that I might consider loaning it for someone else to <ab>use.

During Trial #2, I decided to use the "old school" heating method <see post #1 and that yada-yada about machine tool factory heritage>, and figure out how to REALLY heat the plug.

So I hauled out my "gas axe" Oxygen-Acetylene rig, with a Victor #0 tip to allow me to spread the heat out to a "brazing" type of setup. My concern was overheating, and possibly softening the hex, or distorting the plug, such that the hex would break out before the plug would loosen.

The plug is tight for a couple of reasons that weren't apparent to me until I removed one:

http://franklynb.home.mindspring.com...dsc01107-m.jpg

The plug is a straight thread 38mm diameter, with a 1.5mm pitch. There is a sealing flange, but no "gasket" or sealing ring to speak of. Which means that the prevailing torque, and thread form must be tight enough to seal against leaks, slightly stretching the plug in the hole. I could probably look this up in Machinery Handbook; or if anyone knows where to find it in the service manual, point me to the page -- I have a hardcopy and will scan and add it to this thread.

Anyway, i started Trial #2 with the previous "propane" setup, only to shear my homebrewed tool, almost immediately. it broke at the weld, probably from poor penetration, and proceeded to "corkscrew crack" around the welded joint.

I decided to "fix it right", so after some lathe trimming to improve the "mating" between the two surfaces, and shorten the overall length; and making an "inner shaft" structure from a piece of 13mm hardened hex stock that now goes through the two sockets, and is welded to the 13mm x 1/2" base socket, with a pressed fit into the 1/2" hole in the 19mm hex;
http://franklynb.home.mindspring.com...dsc01085-m.jpg

<note to self; take camera off "spread auto-focus" mode!>
and gas tacking, straightening on the lathe, and then fusion welding the seam in a spiral overlay -- I'm happy!

The application of "gas axe" heat surprised me. I thought, as I was spiraling the heat around the periphery of the plug, that I'd not have a problem getting the plug cherry red.

Wrong.

The heat soak capacity of the block is clearly HUGE. As fast as I could spiral, the plug would absorb it, draining the 1/4" diameter spot of heat into a smoking gray, hot plug. I didn't think to borrow a non-contact pyrometer for Trial #2, but this is in the plans for this weekend's "Ultimate Challenge"; so that I can record the temperature of the plug "at release".

"At release"? YES! To my amazement, after applying the gas axe for about 20 minutes --- the plug unscrewed! Using ONLY the service tubing extension,

http://franklynb.home.mindspring.com...dsc01086-m.jpg and MODERATE torque input -- I'm guessing perhaps 150 ft-lbs, and I've done a LOT of torque wrenching in 40 years -- the plug came out without a hitch.

Another observation: even after breaking loose, I had to use about 50 ft-lbs of torque to unscrew it! Which tells me that its probably an interference thread, which makes sense in its "gasket-free" design. And partially explains why, when seized by time, acids, heat cycling, and galvanics -- its an
ULTIMATE CPR challenge!

500psi *dream*.


And I was happy with 380 dry on mine :)

If you need another one to practice on, I am not too far away.

but really- nice work, good info.

Yes...
 

Please let me know if you figure out how to remove it with a "regular" length breaker bar! :)

The last one I did broke three special tools. :(
I used an oxygen acetylene torch, bringing the plug/block near cherry, 3/4 inch breaker with an eight foot cheater pipe attached to a chain fall, lifting a 300D two inches off the floor, jumped (250 LB) on the front bumper, then the plug moved (dropping the car). :D

This job is very high on the PIA scale!!! :eek:

I made a 3/4" drive tool 25 years ago to remove that plug. The first tool was 1/2" drive and that sheared right off the first attempt. I have removed a number of plugs, without heat and engine in situ, using a 3/4" drive T handle and 6 ft pipe. The air cleaner needs to be removed and the coolant drained.

excellent block plug removal DIY!!
 

I congratulate you. :)

Soon I will be installing several of these in late 50s diesels and one in an OM 636 diesel from the early 50s. Your advice will be oinvaluable.

I just need to get the dimensions right on the plug. If worse comes to worse, I may make my own design!

Yep, that settles it. I'm a hoser. Nice job and nice post, though. Wish I had a garage!

Why not use a torque multiplier? Not sure if there's enough room with the engine in the car to get one in there but with the engine out, it would quickly increase effort.

Eight years ago I did one of these on a 1980 300D. I removed the manifolds and used a piece of 3/4 hex stock, supplied by a neighbor that works at a machine shop.
The hex was Long enough to fit in the plug and leave enough exposed to be gripped by a 3/4 impact socket. The plug finally came loose with a 5-foot length of pipe on a 1/2" breaker-bar, without using a torch. I might not have attempted it had I heard any horror-stories about the possibility of cracking the block, but this forum wasn't around then.

Happy Motoring, Mark

Ummm.... ....I didn't have problems, other than a bit of cussing and wiggling. When I removed daBenz's tank water heater (heater inlet came from that right rear plug spot) there was either an o-ring or a square gasket - this was about five years ago so you'll have to excuse my mad-cow. Same gasket when I pulled the normal plug from the parts car. I just checked my paper "catalog B" (the parts blowup) and there's a gasket in the diagrams for both diesel OM615 and gas M615 blocks. Can anybody confirm that there's NOT a gasket spec'd for the "newer" blocks?

The job wasn't too bad considering the plugs had been there a few decades - 1/2in by 18in swivel-head breaker from the top after removing the air duct, with a 3ft cheater all the way down the breaker handle. Used an extension to a long socket with the long part of a cut-apart L-shaped allen wrench taped to the socket. No heat needed (this time). Made an aluminum foil trough to keep the starter dry and used anti-seize when installing.

I've had the most luck when the very first wiggle is in the wrong direction - sometimes a finger-crosser when you know you're dealing with a tapered thread and you don't know if the other guy tightened it down too much. With a straight thread you're only dealing with corrosion, and it's time for the gas-rig if the first wrong-way wiggle doesn't work. I have "burned out" gaskets to make room for the oil on really stuck fittings.

Brass conducts heat twice as fast as for cast iron (or steel, in the case of something like a house water heater), so heat the brass. You want to quickly expand the plug and crack the corrosion before the hole has a chance to expand too much. This is the opposite thinking as compared to a stuck steel nut on a steel bolt or stud, where you heat the nut.

Never never ever ever hammer cast iron. You can weld a crack after drilling out the ends of the crack, but it's not fun and you'll never know how long it will last. Oil is a lot cheaper than replacing a small engine block. Cussing and wiggling are free.

I eagerly await the ultimate challenge of doing this to a turbodiesel 617 in the car! I was about to install a block heater soon, but it really, really sounds like a giant PITA. Time to go buy a 6' iron pipe from Home Depot. Would an iron pipe be a good breaker bar extension? And would a Snap-on or Hazet 19mm allen socket work alright? (i.e. why did you use 3/4" welded to other sockets, etc?)

be VERY careful guys with heat on a block side. it's fine to heat the brass, and it's fine to get a bit of heat into the block, but IF you are going to be setting a torch in a rig to maintain heat for a long time, BEWARE!!! cast iron will crack. it will get hot, and cool too quickly and crack. I would not get the block anywhere NEAR red hot. and if it cracks, and you "drill the ends of the crack" and try to weld it, you will be looking for a few more cracks. you can gas braze brass solder a crack, but it's really not a good plan. better plan is to keep the heat moderate, and never get the block near red hot.
J.M. $.02...

I have done this twice, and have had good results both times.
I also used a short piece of 3/4" hex stock. I inserted this in a 3/4" drive 3/4" socket with a LONG breaker bar Probably 36". I drained the block, so that I could get it hot enough using my MAPP gas torch. I positioned myself so that I could give short "bursts" of torque to the bar. Three "bursts" and it was off.
I think that the key is having rugged tools that can adequately transfer the force where it is needed. Even a 1/2" drive socket will flex substantially.
Give that I had the air cleaner/manifold/turbo off for gasket/seal replacement, The plug removal took about 30 mins.
It seems hard, but compared to working on old, rusty heavy equipment, it's a walk in the park.

Ja, it was pretty rough...
 

Just ran across this thread and after my experience thought I should chime in. I already had a block heater installed, but it was bad (I thought). It tested open with a meter from the plug, but the cord was a little ragged, so I clipped it off close as I could from above and tested again and still open.

My water pump went out and it was fall, so first winter with the car was in mind and I figured I'd better go ahead put in a new one while the coolant was out. Found a local Benz guy that had one available.

VERY tough to get to being under the turbo and above the starter.

The heater obviously did not have the inside hex due to the connector on it but had a large outside hex. Borrowed a 3/4" socket set, but 1-3/4 didn't fit and 1-7/8 was too loose. OK it's metric, apparently 46mm. Where do I get one of those? Turns out 1-13/16 is VERY close but why would anything SAE actually need that size? 1/8 increments ought to do it one stuff that big. Fortunately this was not the case. Northern Tools had 1-13/16 and was happy to sell me one. Also a short extension as the thing is too far in over top of the starter, but not far enough for the longer extension in the set. But still have to use the breaker bar at a slight angle. Can't quite get right angle for the ratchet.

VERY challenging crawling under the car and getting it all in place and then setting up to torque on it. Have to turn the steering wheel to move the linkage somewhat out of the way. Lots of fiddling and frustration. Hard to set it all in there and hold it in place, let alone be able to apply torque. Have to brace the extension with a chunk of wood against something (turbo?) to stay in place.

You'd think a breaker bar for 3/4" would be plenty long (about 2 feet!) to bust it loose. I braced myself with my feet and gave it all I had with both hands. No go. What do I do now? No room under the car for a cheater bar (without digging a hole in the driveway). Finally hooked a small ratchet strap to the tow hook on the front bumper and to the end of the breaker bar. This finally made it move.

There was JUST enough room to get 1/12 of a turn. Release the ratchet strap. Everything falls out. Replace the socket, breaker bar, wood block again (a very fiddly process done mostly by feel). Hold it with one hand, try to hook up ratchet strap, but it falls out again, so several attempts needed. One more 1/12 of a turn. Repeat this process many times. Finally is loose enough I can turn it with a 1/2 ratchet (glad I got the 1/2 to 3/4 adapter at Northern also!).

That has got to be the toughest thing I've ever done on a car!

After all that, the heater tested good on the bench!!! Turns out the cord was bad right in the connector. The new one (Zerostart) had a different connector, so I could not have swapped just the cord anyhow.

But there ya have it. Use a 3/4" breaker bar (with short extension) and a ratchet strap!

Sounds like it might have been easier to pull the manifolds, if not for the extra turbo plumbing.
My non-turbo TD started easily on the glow-plugs in 20 degree temps this week, though it idled very slow for a few minutes. My manual idle control doesn't seem to be working so I'll need to deal with that after it gets warm enough to work outside again. It was around 10 degrees this morning and I don't torture my diesels at this temperature. Don't need to go anywhere that early anyway, and have a newer gasser if I did.

Happy Motoring, Mark

Unless you live north of the Arctic Circle, a lower radiator hose heater is an adequate replacement that can be installed in 30 minutes without the use of a trucker's vocabulary.

+1

I have a 1500w heater . . . works well when I remember to plug it in!

I have just traded a small box of older comic books for a 5' long 1" breaker bar with 1" to 3/4" reducer, so now I just need a short socket and a short piece of 3/4" hex. I have five to do, but have to work this entire weekend. I saw this and thought about the task, am looking forward to it.

The plan is to heat the engine to operating temp, turn it off and put my son to work... :D:D

Lazy
 

Don't want to tempt another cardiac event.. :eek:

Call me if you need help.. :)

NOTE: Local MBCA meeting tonight.. ;)

I wonder how effective a radiator-hose heater would be on my W123 diesels, as both radiator hose attach at the top of the engine and the flow from the lower radiator hose would be blocked by the cold, closed thermostat.
I do have a 1500 watt heater that has nipples that would fit one of my heater hoses, but I worry if that would be way too much for my 240D or 300D. In any case, as I said before, I have other vehicles, so I don't really need to stress my old diesels at sub-freezing temperatures.

Happy Motoring, Mark

They are quite effective in the lower radiator hose. Not quite as good as the OE heater in the block but good enough to warrant avoiding any work on the plug or OE heater. I have one in my 123 and 116. It'll be 8 below zero in the am and I'm confident both will fire right up.

Edit:
It was 17 below zero this morning and the 116 with a lower radiator hose heater started right up. Didn't try the TD until later in the morning.

Anyone know if there were two types of block heater?

I had the engine swapped on my '85 300D and it seems the replacement block's heater does not match the cable's end fitting. It does plug in, but there is nothing to keep it there. The heater in the block is fine and the cable is intact - it just won't stay in place.

Here are some pics that might explain this better:

Answer
 

Yes, there are other cords.






.

OK Thanks - I will see if I can get the right one.

Related data
 

installing block heater. where to buy 19 mm allen key?
http://www.peachparts.com/shopforum/diesel-discussion/240529-definitive-block-heater-coolant-plug-removal-thread-post2052736.html

So how much trk is required to remove the pulg. That is the real question. Tell me how much trk to apply to break things free. I also think a good flush of the coolant system wil help be removing excess scale from the inside of the cooling system.

I slammed it with a 3/4 IR 2131 titianium that can crank out 1000 Ft/lbs and it did not budge. I use a MAP gas touch and heated the plug and area around the plug for a good 20/30 mins with no luck. I also used aa 30 " 1/2 ratchet from Matco that can break stuff loose the gun can not. (Head bolts on a race truck) I'll head over to harbor freight to sanm a long breaker bar. I like instant heat on a cold day.

Keep the tips coming as I'm going to try this tomorrow.

Hit the plug with a hammer before removal.
The idea is to compress the aluminum seal ring and break loose the threads.
After the hammer treatment i use a 30" long 1/2" breaker bar and a Hazet 19mm Allen socket.
Works every time.

I've succeeded at this once in two tries. Same method each time on 2 617 turbos in the car a 300SD. Tools are a 3/4-drive 19mm hex bit, a 3/4-drive breaker bar and the 4' handle of my floor jack. Oh, and a 6" 3/4-drive extension.

Took the air cleaner off. Then from above inserted the hex bit, breaker bar, extension and jack handle. Positioned the now 6' bar at just below shoulder height, squatted down, put my shoulder to it and heaved with my legs. Came loose in one try with considerable flexing in the bar.

The next attempt was just a year after I broke my hip in a bike wreck and I was afraid to put so much force into it for obvious reasons. I failed and decided to wait a year. So that is now. Maybe I'll get my 6'7" neighbor to provide the oomph.

Victory!
 

Well it only took like a month and two broken 1/2" drive breaker bars, but I finally succeeded in removing the block heater plug from my project car. I ended up getting it by removing the intake, exhaust and turbo (which I was planning to do anyway), liberally applying kroil for like the last month, heating the plug for about 20 minutes, and using a four foot cheater pipe on a 3/4" drive breaker bar with a 19mm hex drive bit. The drive on the breaker bar was starting to twist and I was afraid it was going to break too before the plug finally broke loose. Even when it did break loose it only turned like an 8th of an inch at a time with all of my force behind it. I am glad it finally worked and I hope I never have to do it again!

Hmmm

I've got 3 617's on the floor of my shop... and a 19mm allen wrench, and some pipe... I'm gonna try it with NO HEAT!!!

I may even video the attempt.

Umm
 

Please don't break any bones.

A couple months ago, I tried exactly what you plan: the engine/trans assembly flipped. :eek:

Chain the engine to your big truck, or you might be wearing the cheater pipe. :eek:

.

I will chain the motor down. thanks for the tip!

That block heater is pretty close to the cyl. head....I wonder if that much (30 min) localized heat from a propane torch after the coolant has been drained out would do something bad to the headgasket or the head itself? Maybe leaving the coolant in would help carry away the "too much heat" or absorb it, to avoid damage to the head/headgasket? Great job too on write up, except that part. That part I would not do to my engine. our site probably should'nt condone it either...What do the experts in the mechanics field say?

That block heater is pretty close to the cyl. head....I wonder if that much (30 min) localized heat from a propane torch after the coolant has been drained out would do something bad to the headgasket or the head itself? Maybe leaving the coolant in would help carry away the "too much heat" or absorb it, to avoid damage to the head/headgasket? Great job too on write up, except that part. That part I would not do to my engine. our site probably should'nt condone it either...What do the experts in the mechanics field say?

Recycled for new members
 

Recycled
for new members

all my blocks have the heater in them already... so, I'll not be playing the plug pull game... dang.

I can't ever pass up an opportunity to show off:

http://img100.imageshack.us/img100/8...ockheater1.jpg
http://img703.imageshack.us/img703/1...ockheater2.jpg

I used a 3/4" giant allen wrench, and 5ft cheater bar. Thought the block was going to crack.

I tried removing the plug on a used engine, but gave up. My orginal engine had a block heater, so wanted to swap. I bought a giant hex wrench at Ace (19 mm, ~$17, recall) and used a cheater pipe. I recall trying a propane torch too. Decided to wait until a day when I had the manifolds off and engine installed.

I think my idea on plug removal with no heat will work.

First, tap on the plug with a ball peen hammer. Don't go crazy, just tap on it for a few minutes. Next soak it in PB blaster or aerokroil if you have it, for a day. Next, beake spray the nut clean and let it dry. Next, with at least a 3/4"breaker bar and socket tightly fit in, TIGHTEN THE NUT INTO THE BLOCK FIRST. Just bang tighten it a few times. Then, spray more penetrant... Let it soak, and then apply loosening force solidly to the bar... While solid force is applied... Smack the socket with the ball peen hammer.
Let me know if it works.

I just installed a block heater in my 1980 W116 300SD. I already had the manifolds off for non-EGR swap (my car is a California emissions model) and turbo rebuild. I had been wanting to install one in case I visit a cold climate and thought it was "now or never".

I almost didn't do it, though, because I don't really have the money and figured it would take about a week before one would arrive. EBay had some good deals, as did some online parts stores. It seemed I had two choices: genuine Mercedes-Benz which was about $200 (and was made in Canada) or a Zerostart (love the name), which was a lot cheaper and also made in Canada (maybe they make the genuine Mercedes ones?).

The Zerostart appeared to be very high quality and I chose it over genuine Mercedes-Benz, not just for the price, but because it was only a one-piece unit and had a nicer power cord arrangement with a cap to cover the prongs.

I looked up block heaters on O'Reilly Auto Parts' website just for fun and they had one of the Zerostart block heaters at their warehouse for only $60. So I had them order one in and had it the next day. The part number is 310-0105 or Q6200009 and fits 38mm plug threads. It looks like Pelican Parts has genuine Mercedes-Benz ones for only $39! Mercedes-Benz Block Heatr Kit Q6200009 - Pelican Parts They also have the Zerostart heater: Engine Heater 9002034895 - Zerostart - 900-203-48-95 | Pelican Parts .

To remove the plug, I bought a Husky hex key socket set from The Home Depot for $25. It came with the proper 19mm hex key and also had a 3/4" key which is the same size if the first were to break. O'Reilly Auto Parts had a smaller set for $20 with only the 19mm key, so that was an option.

I tapped on the plug (not the block) with a sledge hammer and then I put the 19mm hex key socket on a 36" breaker bar with a 24" pipe slid over the end, gave it some force, then pulled it back toward me, and then back the other way. It didn't budge.

So, then I tapped the plug with a hammer again, then put a MAPP gas torch on the plug for about 10 seconds. I put the socket back in the plug, pulled the breaker bar toward me, and then pushed it away and jarred against the bar a few times (which was bowing quite a bit). I finally heard a SNAP! and then I was able to turn the plug a bit. So, I drained the coolant from the block, then loosened the plug while rocking it back and forth a bit to clear up the threads.

The new block heater came with an aluminum crush washer. The plug that came out of the block had no apparent sealing ring. I installed the block heater with the aluminum crush washer and a little bit of anti seize compound on the threads.

The block heater takes a 46mm socket to install. They can be ordered in at auto parts stores but are usually at least $30 each. I was at Harbor Freight with my roommate and they had a 20 piece jumbo SAE socket set (of the highest quality ;)) for $130 on sale for $60. He had a coupon and ended up getting it for $47, so he let me use the 1 13/16 socket which fit perfectly. There were no torque specs, so I tightened it using the breaker bar and my judgment.

The power cord can attach 180 degrees in either direction. I ultimately had the cord point toward the firewall and routed it with the battery cables under the heat shield toward the front of the car, coiled up the excess length and tied it with a strap, then routed it out under the right headlight and behind the bumper so it can be plugged in without opening the hood (which let's assume would be frozen shut and covered in a foot of snow if I ever get to use it).

http://www.peachparts.com/shopforum/...d-imag1349.jpg

wow that is a beautifully clean engine!