W123 Diesel Block Drain Plug
 

I'd like to buy a new one before loosening the old to drain the block of coolant, but can't find one anywhere.

Does anybody know where that short 19mm weirdo can be found?

I'd hate to get it out only to find it in poor condition, or the washer in bad shape, etc.

Any ideas?


Thanks in advance, all.

The washer you can find just about anywhere. A simple copper crush washer should be readily available at your friendly neighborhood Ace or Tru Value.

As for the bolt, I'd imagine the bolt dimensions are detailed in the coolant change portion of the FSM. Unfortunately the maintenance part of the FSM isn't available online right now. You'd have to find someone with an old paper manual or get lucky and find a PDF of it floating around online somewhere.

If you call your dealer and describe the part they can probably order one.

That said I've done this job on numerous cars and never has the bolt looked anything but A-OK. I'm not sure it's something I'd stress about. Just be sure to seat your socket on it well before turning it to avoid rounding it.

Thanks. I'll call the local stealer and see if one is available. I believe the washer is 10x14x1 aluminium, and available from ********az.

When you've removed the block coolant drain plug, have you accessed it from up top or down below? I've located it by jacking up the car and getting underneath, but it seems like an odd angle. Can this be done from above by removing the air filter housing (if the turbo isn't in the way)?


Thanks for the advice!

Access from above can be done, but it's entirely by feel. Even on the non-turbo cars it's virtually impossible to see while also reaching down there to get a socket on it. That said, I do like to be standing above the car when removing the bolt to avoid a coolant shower. Usually this means I crack it loose from below while I can see it, then get up top to finish the job when rounding it is much less likely since it's already started.

One thing I've found that helps a lot is to have a wood block to use as a fulcrum. You'll likely be using one or more extensions and possibly a u-joint to get the correct angle and it can be hard to get enough leverage without the entire assembly flexing up or down. If you can put the wood block under the head of the socket wrench it will help it turn without moving in other directions.

Thanks. Makes perfect sense. I was considering a 10" extension with a swivel.

I just removed mine a couple of months ago, it's a very short bolt (plug). I think I used a couple of different wrenches. Open end and socket. I was cautious because I've had problems before, so I cracked it loose and then ran it back in and out a few times and had no problems. I didn't change a washer, I'm not sure it even had one and no leaks.

Thanks. You removed it from underneath?

Block Drain Plug
 

This is what I use on my NA engines , feel for it then work blind , no need to touch the air cleaner at all .

Ever seen the plug itself available for purchase? I might be worrying overmuch, but I sure would like a new one on hand ... or at least knowing I can get one.

Nosir , I have not .

My '81 240D's water jacket was so bad , the chunks tore a HOLE in the water pump housing and it took me a LOT of Citric Acid flushing before it remained clean but that mild steel plug is indestructible unless you use a 12 point socket or open end wrench on it or other wise round it off .

As mentioned : you *might* need a short cheater handle on your 3/8" drive flex handle , I did the first time I took it out .

WHY are you keen to remove it ? .

I'm actually hesitant to remove it. Car has been running hotter than normal. I'm swapping out the t-stat. Haven't changed the coolant in the three years I've owned her and am about to drive it cross country. Thought it might be a good idea to drain and replace. I've got a 6-point 19mm socket (1/2" not 3/8") that looks like it will fit it nicely. I've got a 24" swivel breaker bar too, if needed.

I was thinking of draining and replacing the t-stat and fluid, rather than a flush. I've got an airlift system to get the air out and the fluid in. After the long drive, in a year or so, I'll probably do a proper citrus flush. Right now, with 2471 miles looming, anything plugged up may well be my friend. At least that's my thinking.

Thanks for your reply.

Cooling System Service
 

I see .

As I'm a Journeyman mechanic who only (or so it seems) buys junkers and cast offs , I get rather picky about the details because I drive a lot (800 miles every 7 days) and getting stranded pisses me off badly .

Anyways , best of luck with the trip , as it's still Summertime , I'd prolly mix up some Citric Acid and distilled water and fill it then carry several gallons of distilled water in the trunk then hit the road ~ in a thousand or more miles the mix will be dead black and you can flush it out anywhere then add the good coolant .

That's me though ~ I like looking into my radiator and seeing bright shiny metal instead of solder blooms and red liquid .

I appreciate the advice. Making the trip mid-October, so it should be mild. Hoping to sort out any problems in advance. I'm planning on taking distilled water.

Thanks again.


I should probably be more worried about my wife ... she'll be right behind me in her ML. It's got 1/4 the miles of my ol' W123, but of the two I feel far more confident about the old timer.

If you remove the block drain and replace the crush washer, it won't leak. A good flush is what I'd do to get the deposits out of the cooling system. If you're going to flush it, the ; ck drain absolutely should be removed to get a good rinse after the flush. Flush the heater core backwards while you're at it so you have good heat in a few months. :)

Citric Acid Cleaning
 

If you're driving it now , at the worst it'll take one week of daily driving to get it whistle clean .

Me , I'd not trust it on a long road trip if it's running too warm now as heat rise is slow but steady , you're begging for trouble in October as it is .

I did mine in Summer and yes , I left the heater on (both knobs , 240D's have split heater core diversion) and drove with the windows open , cooking like a sausage because if you don't do it right , no point in doing anything .

Best of luck here , keep us posted , I love my 240D more than my fancier and faster Turbo OM616's .

Slow , though :rolleyes: .