"new" W124 leaking coolent
a few days ago i discovered that the coolant leaked. the fluid comes out drip, drip, drip... from the underbelly of the engine compartment, at a point just ahead of the center of the dashboard. when there was still enough fluid to leak out, it would stop about 15 minutes after the car has stopped, and, after cooling off, the fluid level would have gone down an inch or so from the "level" in the overflow tank, and remain there. the "low coolant fluid" lamp would light up.
the temperature gauge would show 80 degrees (centigrade) steady throughout, even though the coolant warning light has been on for quite a while, all this while driving at moderate highway speeds.
the engine lube level has been constant, and no excessive smoke was detected in the nz official visual test done last week.
questions: (1) what is wrong and what kind of repairs are we talking about? (2) what is the normal operating temperature of the model when air temp is about 12 degrees centigrade (about 55 degrees fahrenheit)?
thanks! joseph

many thanks. joseph
From the sounds of it your problem is pretty mild. Trace the leak, all leaks have a source, find it. Specifically look at all the coolant hoses. If they aren't tighten down tight enough they can leak.


Many instances it is a "hex nut" headed plug designed to be removed for insertion of a block heater. Slow leak BUT when under pressure gushes hence you don't seem to witness huge amounts of loss.

Recently helped a 126 guy out with finding the part numbers to resolve this. Get back to us if it this.
If it's not that case you might also check out the other side of the engine block at the back as shown in this picture below.
It is also notorious for an "o-ring failure" at this location.
Last edited by stormtigers; Aug 2, 2013 at 08:56 PM.
Seems the coolant plug used in Mercedes 300D is 38mm and 1.5mm thread pitch, please confirm this is the plug above.
Do you have a part number ?
Where does the picture come from ?
Car engine details and year ?
Thanks for your support.
Last edited by RC200; Feb 3, 2014 at 04:32 AM.
Seems the coolant plug used in Mercedes 300D is 38mm and 1.5mm thread pitch, please confirm this is the plug above.
Do you have a part number ?
Where does the picture come from ?
Car engine details and year ?
Thanks for your support.
Car is a 1988 Mercedes 300CE (M103 engine)
Engine Oil Galley Plug Seal
VictorReinz Engine Oil Galley Plug
VictorReinz Timing Cover Gasket; O-Ring, 36mm
(I suspect it may be exactly the same size as the Timing Cover Seal hence the latter description)
But the Part Numbers I believe you are looking for to suit an M103 are as follow :
SEAL - Part No # W0133-1642642
PLUG - Part No # W0133-1637881
Last edited by stormtigers; Feb 3, 2014 at 04:45 AM.
Car is a 1988 Mercedes 300CE (M103 engine)
Engine Oil Galley Plug Seal
VictorReinz Engine Oil Galley Plug
VictorReinz Timing Cover Gasket; O-Ring, 36mm
(I suspect it may be exactly the same size as the Timing Cover Seal hence the latter description)
But the Part Numbers I believe you are looking for to suit an M103 are as follow :
SEAL - Part No # W0133-1642642
PLUG - Part No # W0133-1637881
Because in this thread (car is 300D):
http://www.peachparts.com/shopforum/...al-thread.html
the plug is 38mm / 1.5mm thread pitch and this is what I'm looking for.
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Because in this thread (car is 300D):
http://www.peachparts.com/shopforum/...al-thread.html
the plug is 38mm / 1.5mm thread pitch and this is what I'm looking for.
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