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  #1  
Old 12-12-2002, 05:26 PM
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Location: Accokeek, MD
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Coolant leak 1987 300E

I have a coolant leak that built up gradually and which is now dripping down alongside and off the oil pan at the left side of the engine. I cannot see where it is coming from because the intake managold is blocking my view.

I suspect a rusted out blow out plug.

Does anyone have insights as to what else it might be or who can confirm my suspicions about the blowout plug?

If it is the plug... can I do a patch with liquid weld or similar sealant till spring because I do not have a garage and it is winter here with snow on the ground.

Thanks.

Earl
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1993 190E 2.3
2000 Toyota 4x4 Tundra
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Old 12-12-2002, 08:35 PM
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You didn't say if it was the front or rear of the engine Earl. If it's at the front it may be the water pump. This usually causes the drip to be near the oil drain plug or down the front of the oil pan. There's an inspection hole on the underside of the pump just to the rear of the pulley. You'll need a small mirror(like a dentist uses)and a flashlight to see it. If the leak is toward the rear it may be the O-ring that seals the heater hose fitting into the cylinder head. Pressure testing is the only way to tell for sure. Good luck
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Old 12-12-2002, 10:54 PM
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Thanks Iluv...

I am somewhat relieved because you seem to be saying that it is not a blowout plug. (Does Mercedes have blowout plugs?)

The coolant is leaking down the side of the oil pan not the front... so it looks like it might be the O ring you refer to.

Also it seems to leak worst at idle after the car has been driven on the highway... but I'm not certain of that.

What has to be done to replace the O ring? Must the intake manifold be removed to make the repair?

We have had snow here and I simply have not had the oportunity to take the air breather off and get a better look.

Earl
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1993 190E 2.3
2000 Toyota 4x4 Tundra
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Old 12-12-2002, 11:47 PM
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Earl:

Mercedes core plugs screw in, not a chance that is what is leaking. More likely to be a bad head gasket than a core plug.

My money is on the water pump, most likely thing to go.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #5  
Old 12-13-2002, 12:24 AM
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Well Peter that is a relief to know that Mercedes does not use the blow out plugs similar to the ones on my old Ford flat head. I kinda figured Mercedes would have a better design than plugs that could rust out.

Quite frankly I would like the leak to be in the water pump but I secretly think there may be a problem with the head gassget because there was oil in the water when I first got the car used about 2 years ago.

Also I do not see how water from the pump could get that far back along the side of the engine. Have you ever experienced water dripping down off the side of the oil pan if the leak was coming from the water pump? Are Mercedes water pumps at the very front of the engine like other cars?

Thanks for helping out.

Earl
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1993 190E 2.3
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Old 12-13-2002, 09:51 PM
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Earl, if the O-ring is leaking you're in luck! It's easy AND cheap. With the oil filter removed, just remove the two 6mm allen screws on the fitting(after you dis-connect the heater hose). Pull out the fitting, clean the sealing surface inside the hole, and replace the O-ring. The most expensive part of the job is the coolant. I hope it works out for you. Good luck
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Old 12-14-2002, 01:52 PM
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Oil in the coolant means either a cracked head or a leaking head gasket.

I've not heard of the 603 head gasket leaking coolant out the side, but when composition gaskets (rather than the old asbestos/copper ones from days of yore) fail, they usually blow at the coolant or oil passages -- the sealant applied during manufacture goes bad, and the coolant in particular will dissovle the gasket material.

That means it can easily erode it's way out to the side of the block and dribble.

Find a mechanic's mirror at the auto parts store -- they are usually about 2x3" on a swivel on an extension rod -- and see if you can use it to peek under the exhaust manifold. Should be obvious if you have coolant leaking there with engine hot.

If you still have oil collecting in the coolant tank, chances are a cracked head, but that won't leak externally, you will just have coolant dissapearing. The good news is that if someone fixed either a blown gasket or a cracked head in the past, the oil will hang around forever, even if you flush quite a bit, so traces are not a panic item unless it keeps accumulating!

That's the story on my 300D -- oil in the coolant tank when I got it, was planning on a new head, but no more has appeared, and the rad is brand new, the head is suspiciously clean......probably the secont (or third!) owner got bitten for a new head.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #8  
Old 12-14-2002, 07:10 PM
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Peter...

All of what you say is really good news. I have been wondering about that oil for a couple of years now but it has never returned... it was there when I bought the car.

I've searched the entire block and head gasget for a leak but can find nothing. The leak seems to be coming from behind the water pump. I put the mirror under the area where the weep hole is located, with the engine running but the mirror did not get wet so I figure the leak is coming either from the gasget on the water pump; the head gasget behind the pump or the weep hole of the pump. In any of these possibilities I have to remove the water pump to find out so today I ordered a new pump from Phil at Fast Lane and I've begun the proceedure for taking out the water pump.

I'm currently removing the bolts from the compressor. The fan, pullies, distributor etc. are off and I hope to have the pump out by tomorrow and the problem diagnosed by then. The pump should be here by Tuesday... and then put it all back together again.

Thanks for sharing your experiences with me.

Smiles.
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1993 190E 2.3
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