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Old 01-30-2009, 05:00 PM
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Join Date: May 2007
Posts: 114
Help - missing coolant

I think I already know the answer to this, but I want to ask anyways.

1987 300E m103 engine

started loosing coolant, I know its not the head gasket because that is new (<9,000 mi). I have checked for coolant in the car - everything is dry - sticky, but dry. Recently began to smell coolant every so often and can hear gurgling when the heat is first put on from time to time.

I looked under the car and saw dripping from where the oil drain plug is. Traced it back up the block as far as I could see. Judging by the spot, could it be the back of the water pump is failing/failed?


87 300E
202k on the clock
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Old 01-30-2009, 05:10 PM
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Join Date: Apr 2002
Location: westchester, ny
Posts: 747
Check the heater hose coming out of lower back of the engine block on the driver's side, especially where it is connected at the block. The hose may have cracked or the o-ring may need replacing. That happened to me. Easy DIY.
87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)
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Old 01-30-2009, 05:17 PM
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Join Date: Jul 2008
Posts: 1,236
It could be the water pump. Could also be a freeze plug. Also, there's an O-ring at the back of the head where the lifting eye attaches to the block. That should have been replaced when the head gasket was done, but they might have missed it.

Double check that all the hoses are good and snug. Over time, the rubber gives a bit and you have to tighten the hoses a bit to compensate.

I hate to say this, but just because the head gasket was recently replaced does not mean that it "took". Usually, there is no problem after replacing a head gasket. Sometimes, it just doesn't seal up afterwards and you have to do it again. Hope that's not what you're up against.

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Old 01-30-2009, 07:16 PM
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Join Date: May 2007
Posts: 114
After further assessment here is where I stand:

I took some stuff apart and think the leak is most likely coming from the lowest and furthest outboard bolt on the back of the water pump, don't know if that conjures up the right visual or not, but I'm pretty sure its coming from the water pump - there is a visible "wet" trail from there down the block.

edit: I know its not the head gasket - I did it 8 or 9 months ago and my original mileage was off - its been more like 15k mi since it was done.

I did take the reservoir cap slightly off, as in the 2nd position and it seems to have really lessened the leak big time.

The main issue here is not whether I can fix the car, but its whether I want to fix the car. I'm moving to DC in a couple weeks and won't be needing a vehicle (metro). Its just disheartening that the benz couldn't be good to me for another 2 weeks.

So this brings the next question - who wants to buy my busted benz? lol
87 300E
202k on the clock
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Old 01-30-2009, 07:20 PM
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ich fahre, also bin ich
Join Date: Mar 2002
Location: South Florida
Posts: 1,622
Could also be the wapu shaft seal. There is a hole underneath where coolant starts to leak from.
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Old 01-31-2009, 12:07 AM
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Join Date: Oct 2008
Posts: 557
it's not bled steam in a radiator....air pockets...gotta bleed the thing....
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