Let's Wire Up the Block Heater!
 

It’s getting cold. If you have a diesel, that means that you might want to fire up the block heater. My ’95 E300D is new to me. I did not know if it even had a block heater. A bit of research determined that it does, and I believe that all diesels from at least 1995 onward have block heaters. BUT…they are not wired, unless you or the previous owner took the car back to the dealer for the free heater cord install. (Canadians and the rest of the world – it may be different in colder climates.) Look behind the small removable rectangular section of your plastic front grill on the passenger side to see if the cord is there.

So, I looked, and my cord was not present. So I ordered one – it’s cheap, as it should be. Here’s how to install it. An easy one-beer job.

First jack up the front of the car, place your jack stands, and remove the plastic belly pan, if you still have one. This photo shows what you see when looking down from the top side. The heater is located on the passenger side of the engine block, below the exhaust manifold. It has a black plastic cap on it, assuming it is still there.

Because you are working next to the exhaust manifold, wait until your car is cold to do this job.

The cap was tight on my car so I used some slip joint pliers to grab it and loosen it enough to remove it by hand. It’s a tight fit, but you can reach it from above without much difficulty.

This close-up photo was taken from below and shows the heater with the cap. Nice to have the close-up feature on the digital cam – and long arms to hold the camera where my eyes couldn’t see!

This photo shows the view from the top with the black plastic cap removed – you can see the brass threads on the heater itself.

This photo is a close-up of the heater with the cap removed.

This photo shows the heater cord. 3 prong plug on one end, and two holes on the other to fit the prongs on the heater.

Now you have to get under the car, and plug the heater cord into the heater itself. A bit of feeling and dexterity required, but it is not too difficult. You have to do it pretty much by feel, because you can’t see too well up there. Actually if you are adventurous, you could probably remove the second plastic belly pan and gain more access and visibility under the car, but I did not feel like doing that, and the job is not too hard with it still in place.

So now you have plugged in the heater, you have to route the cord out the front of the car. I have not seen how the dealer techs do it, but I chose to run mine along the transmission oil cooler line. I just zip tied it along that tranny cooler line about every 6 inches or so, no big deal. Then you snake it out of the front of the car, out the trap door in the front fascia.

Here is the last photo with the cord hanging out the front of my bug splattered fascia. Don’t make the same mistake I did at this point. You have to secure the cord firmly in place so it can not drop down and drag on the pavement. Another zip tie or two should do it. I did not do that and managed to drive about 80 miles with the cord dragging! Chewed up the plug quite nicely, but it still works. Now go have another beer and change the oil while your car is nicely up on the jack stands!

Chris W.

It brings a tear to my eye when I see work this well documented...

Picture worth a thousand words
 

thanks a million for posting block heater pics--just what the doctor ordered. You said cord was not expensive-where can you get a cheap one. One dealer quoted me 60$ for just the cord. That sounds like robbery.
Taylor

Phil at Fast Lane for parts
 

When in doubt, just call or email to Phil. He's superbly responsive, and the price is always competitive, IMHO.

Rgds,
Chris W.

Excellent Documentation Chris!!

I was going to purchase my replacement cord from Phil (for $16.xx) when I called the local M-B shop and they had one for $15.xx. So I just purchased it from there and installed it the same day. :)

Anyone care to share the dealers routing on their stock cord setup?
I am curious to see where they stuff it and make it look presentable to the "finely tuned eye" of mercedes owners :D

Very nice documentation.

Pictures of my W210 as done by the dealer are here.

I just installed my block heater (not just the cord...but the element too!)
I had to break out the oxy-acetele torch, BFH, and a home made tool to get that damn plug out of the whole.
Crazy.
I will post pictures later...I document like this post...:)

Next time I will hard wire (solder) the Ground tap...
 

from the cord to the heater, because as time goes on the heater gets tarnish and the connection goes bad.
I do this a lot on my connectors on both my Volvo and Mercedes..

are block heater normally installed in older models too? I'm wanting to put one in my 83 300D. Where is the element located or where would I have to install it? In a freeze plug?

there is a threaded hole in the block above the starter which the block heater can be screwed into. "All" you have to do first is remove the threaded plug :laugh: :laugh: :laugh: :laugh: :laugh: :laugh: :laugh: :laugh:

thanks for the reply. I'm "on the hunt".

Needed some blue wrench, right? I just learned that my '85 300TD doesn't have a Block Heater. My '79 does and I wish I had driven it to Texas and back, it was pretty rough starting one day last week when it was down to 25 degrees. I tried once to install a BH in a W123 300D, I had a big hex wrench in the plug and with a long extension pipe I was able to lift the engine up off the mounts (including tranny) but it never broke free. I figured it wasn't worth busting my back in order to install a heater I probably never needed. What a job! OTOH if I lived in colder climates I would have gone for the torch. Still, a terrible job! I am happy that MB is installing them at the factory now, have one in my '87 300D in case I ever drive back in the cold belt.....Brrrrrrrr!
1971 220 (gas) 4-spd manual 106441
1979 300TD w/ ’85 turbo engine 296650
1983 300D 243280
1985 300TD 223470
1987 300D 262300

I would almost say don't even try this job without the following:

-A good allen wrench (19mm) and a cheater bar (lenthen's the handle lenght of the allen wrench
-A reasonably hot torch
-Perhaps some ice?
-A BFH (Big f'in hammer)
-Perhaps some penetrating lube.

When you put the heater and adapter in, do us a favor and put a dab of anti-seeze on it ;)

I would advise against using Phil under certain CIRCUMCISIONS tho.

Mainly when it is a prophylactic part order. For instance, if I think one of the 5 hoses is leaking and so I order all 5. Well, I am a cheap bastard and if I can get away with changing 3, I will return the other two. It would probably cause more problems to do than going to your local shop and buying all 5 and later returning 2. Not sure what his take on it is but I would think it would be an inconvenience for him.

lube that sucker !!!
 

I'd put some grease on/in the connector at the block heater-mine was getting a little corroded looking (%$#! road salt!); I'd be tempted to anti-seize the element if I ever had to take it out.

Thanks again for this document!

It has been two years since you put it up, but it is still helping people out. I looked up and thought I saw the plug cover, but after doing a quick search, finding your thread, then reading/looking I was sure that I was in the right spot.

Thanks again!

-Jim

Bump and a little info.

From what I just read on another thread there is a good reason for the different prices on the cords.
$70 at the MB dealer - extra heavy wire, with heat shielding insulation, with retaining screws.
$32 at the MB dealer - heavy wire, no heat shield insulation, with retaining screws.
$14 from fastlane - regular wire, no heat shield insulation, no retaining screws.

I have the one from fastlane and it works fine for me. If I was going to do it again the only change I would make would be to put some silicone sealant around the plug to seal out junk and help act as a retaining screw.

-Jim

Here is the cord with the retaining ring, insulation and plug cover. I didn't get it from the dealer.

Chris

Here it is installed.

I wire tied mine as well.

All done.

Mine had quite a bit of corrosion after 20 years. I sprayed it out with brake cleaner and let it dry before I hooked it up. How did I know if it worked? I could here it running almost as soon as I plugged it in.

Chris

Mine was still bright and shiney. Like it had never been opened and the cap had been sealed up tight.

I wondered about how to tell if it was working also, until I heard the hissing sound after a minutes or so. I love the plug!

It only takes a couple of hours to heat up the engine, especially if it is in the garage. I have mine on a timer in the winter.

The other thing I do is loop the cord through the steering wheel. It is hard to forget to unplug it that way!

-Jim

I have mine on a timer too, but it's the one on my truck. Both vehicles are in a 45 degree garage so I only plug it in so I can have heat right away. The manifold heat only comes on for a couple seconds also.

Chris

Damn, thats a nice setup with the retaining ring and all. Where did you end up getting it? I got mine but it didnt come with the retaining ring.

I too had tears from the fine documentation, and I propose and new standard of job time spec'ing. Instead of hours labor, I propose we rate jobs by beers. For example, as our fearless Chris W. has mentioned, putting the electric cord on the heater is a one beer job. Changing the oil is a 1 beer job.

Apparently putting in the element is a 12 pack job. 6 for while doing to job, and 6 for cussing and telling the story afterwards.... Is that about right Brandon314159

The heater block is the cat's meow for cold weather starting. We have been plugging in for 3 hours and she starts right up in 20-30 deg mornings.