block heater 1976 240D - PeachParts Mercedes-Benz Forum

kchemers · #1 11-24-2002, 11:28 PM

1976 240D. I purchased a block heater and the instructions show 2 drain plugs on the passenger side of the engine. 1 is directly above the starter and the other is alittle closer to the front of engine. Which is the one I use? Also what size allen wrench is used? I am guessing 11mm.
Thanks, kchemers

leathermang · #2 11-25-2002, 02:30 PM

If you are talking about the plug which is in line with the front two freeze plugs.... mine has a flat to flat measurement of .730 inches... which , when I compared to my metric wrenches seemed to be exactly 18 mm.... I don't have large allens With the size marked on them ....
If you have the allen MB oil pan drain plug wrench.... it would not surprise me if they thought ahead enough to have this the same size as that one.... good luck...

190D22 · #3 11-25-2002, 04:05 PM

How many watts are these factory block heaters? And how hot do they get the engine? Owner's manual says it's only needed when you're in temps 10F regularly. Would it not be worth it for me to run mine for an hour each morning at 32F?

#4 11-25-2002, 05:31 PM

kchemers,

The plug you want is the one right above the front of starter which puts it's location about in the middle of the length of the engine.

I am familiar with the recessed hex size on the w123's, but am not sure if yours is exactly the same size or not. The w123's are a 19mm recessed hex. And fortunately a 3/4" hex bar of steel fits very nicely. We put the end of a 3" length of this bar into hex of plug and then got onto 3/4" hex bar with a 1/2" drive 3/4" (6 point) socket w/ breaker bar. Next, slipped a 5' long chumk of 1 1/4" pipe over breaker bar and put all of my 250 lbs onto end of pipe. Took 4 attempts before she finally broke loose: 3 of those with a cold block and the last after warming the block area around the plug with a torch.

It would be better to use a 3/4" drive socket and breaker bar if you have access to one, as we were flexing the snot out of our 1/2" drive.

On a non-turbo such as yours, I would recommend removing air cleaner and then exhaust manifold (provided your threaded studs are not rusted too bad). This makes the job a lot easier to do from the top w/ lots of room to work and lever clearance for pipe bar persuader.

I agree with it being very worthwhile in a cold climate. My wagon w/ nearly 300k on her starts and purrs nicely as long as she's plugged in (when below freezing). Aside from that aspect, I am sure it's better for the longevity of the engine to be starting her with thinner (warmed) oil, as opposed to heavy (cold) syrup.

I believe that our block heaters are 500-600 watts. I put them on an electronic timer that is set to come on 3 hours before I need to leave in the AM. I don't think one hour is enough to bring coolant up to temperature. I remember reading on this forum last year about this time that someone wrote it takes between 3-4 hours.

It sure is NICE to have instant heat blowing when you back out of the garage, though!!

#5 12-18-2002, 07:35 PM

I am about to install a block heater either tomorrow or friday, but I still have questions on how to install it. I now know what to do to get the freeze plug out, but I am still trying to figure out how to get the heater installed. I still have no idea what size wrenchs I need to tighten it, and how do I get a touque wrench in there? Do I need to install the "reducing bushing", I talked to a mechanic a while back and he told me I didn't need it. It's nice that they included the instructions, but they just didn't go into much detail.

#6 12-18-2002, 08:00 PM

123c,

You can just tighten it up with a large crescent wrench - no torque wrench needed. It has it's own flat seal washer to keep it from leaking once it's snugged up to block.

I've never seen a bushing on these things. The ones that I have seen come as one brass unit w/ a large hex nut (approx. 1 3/8" across) and male threads that fit right into the block - nothing else needed.

The cord makes a connection to the heater and you route the cord towards the front of the car tying it off to a heater hose w/ some plastic cable ties along the way.

#7 12-18-2002, 08:12 PM

Kirk,
Thanks for the information. I guess I have a different style, It's still made out of brass, but comes in two pieces. The instructions give the tourque specs. for each piece. That is why I was asking about the tourque wrench. I will try posting pictures of it later on, after the batteries for my Digital camera recharge.

#8 12-18-2002, 08:25 PM

Here is the picture of what I got.

#9 12-18-2002, 08:32 PM

The plug is 19 mm.

You can probably get by with slightly less--mostly they are fairly hard corroded shut. An impact wrench is the best solution.

diesel don · #10 12-18-2002, 10:14 PM

123,

The pic that you show is identical to the two that I've installed and the ones that Kirk has installed (we live close by each other).

As for the install, you put the silver washer around the larger piece and screw that in first. Just put a big honkin socket on it (I had to borrow one from a tractor guy). Tightened it as hard as you can. Don't worry about torque stuff.

Next, you screw the smaller piece into the center of that (the one with the actual heater on it).

However, I must warn you that the install is a cakewalk compared to removing the old plug. Kirk has done them from the top while I have done them from a pit underneath.

In both instances my vocabulary has expanded and I barely made it with all my resources. Five foot pipes are no joke and when they give, watch out. I had to remove one piece only from underneath (near the tie rod stuff).

When I first did it, I had Aaron Bonger (from the forum) send me his tool in the mail. He had welded two males together. This was by far the easiest of the two installs. I tried to do my own on the second one with a couple of nuts (3/4) screwed onto a bolt. What a joke. Snapped the bolt right in half.

However, once you are done, you won't regret it. Works like a charm and you have nearly instant heat as well from the blower.

Don

dave240 · #11 12-18-2002, 10:33 PM

Eric,
Nice photo. I installed my block heater last night, my hands are still recovering. Appears you have the same heater as I. (400 watts)

to confirm previous posts;
The starter needed to come off, as did the air cleaner.
The block needs to be drained as you will probably need to apply heat.
(smaller drain plug in front of starter)
Get the car secured on ramps, jack stands or lift, cause you'll need to apply your weight to remove the existing plug.
existing plug takes a 19mm or 3/4 hex.
Get a 3/4 inch drive breaker bar if you can, or better, impact.
Prepare for some blood, sweat & tears.

your car may be different, but on my 123, I did use the reducing bushing (fine threaded w/aluminium washer).
I installed the 1-3/8 inch heater plug inside the reducing bushing first as not to collapse the bushing when installing into the block.

Installing into the block I did not use a torque wrench, just a large cresent as I did not have a 1-3/4 inch socket. No leaks so far. (use good thread compound).

good luck

mplafleur · #12 12-19-2002, 10:39 AM

All good info as I plan to install one soon. I can't believe that this Texas car didn't have one!

Don,

Did you get that new battery installed yet?

diesel don · #13 12-19-2002, 06:18 PM

Note:

If you can get under the car, like in a pit, you don't need to take off much. I've done two by only removing the lower rod.

Michael:

I have a battery in my garage that I'm going to put in it. The voltmeter indicates that its holding a charge very well. I chucked the one that was in it. Seemed to die overnight.
Can get to my email so I don't know if you wrote me. Will have it tomorrow

dp

mechmagcn · #14 12-19-2002, 07:59 PM

Not to sound smart a**ed. but one can tell there are not many machinists here. Drain the coolant, heat plug with torch (needs to be red hot) then cool the plug with water. Then you can screw it out with your fingers:p
Jeff

BobK · #15 12-20-2002, 07:36 AM

Somebody asked how many watts the block heater draws. Seems to me when I checked it with my wattmeter, it came in at 390 watts. I have done some crude testing and from my experience, the coolant reaches maximum temp in about two hours. I have my car plugged into a timer that comes on two hours before the car is needed in the morning. Costs me about a nickel a day to run it.

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