Fellow MB Techsters.....I am new to Benz ownership.One month in with the "BABY" running well (162k miles), I had a small coolant leak turn to massive, without being able to pinpoint a location of the leak. Here are the facts:

1) started dripping from bottom of radiator, drivers side. This appeared to be the end of the trail with the source unknown.

2) no pipes or hoses apparently leaking.

3) car had great heat.

4) No noise from the H20 pump.

5) When I jacked up the car, ran it, and crawled under to find the leak....it stopped leaking. When I put the car back on terra firma ....it gushed.

6) Loosened the radiator, lossened the top radiator hose and the plastic nipple came off with the hose.....arrrrhhhhh Took off the drive belt and the w/p had no play in the shaft.

I had two mechanics offer their opinion. One said the weep hole on the h20 pump was dumping the coolant. But no other symptoms there to back that up.

The second said it was probably a freeze plug failure. I'm starting to think this is it. The car is from "the Ocean State" and of the plugs I can see, they appear to be rusted. The source is likely to be on the intake side of the engine, and I have a sneeking feeling there is a hidden plug there that
may have crapped out. I was wondering if there is one on the block behind the h20 pump housing? Can anyone tell me how many there are total, so I know the correct qty. to order? .... Many Thanks.....

How about filling up the system with water, and use a pressure pump, put about 12-15 pounds of pressure on it, and wait. You will be rewarded with a drip.

My water pump leaked when I installed the serpentine belt correctly, for the first time, then stopped. 5 years later, it started dripping again, and I replaced it.

It took an hour and a half for the leak to start under pressure, but it did start. Ended up replacing the radiator due to a cracked tank, too. Glad I did, as the coolant temp went down nearly 15 degrees. It's a happy Benz these days.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

Thanks for the suggestion Holmesuser01. Any idea where's the best place to purchase or rent one of those pressure pump units? Is this (possibly) just a fitting substituted for the radiator cap and connects to an air compressor?

Not a compressor. Dont want to destroy it!! The one I'm thinking of has a connector that replaces the radiator cap, and a little pump handle, and a pressure gauge. Theyre not very expensive at the auto parts stores.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

So you just said the plastic piece the upper hose attaches to on the radiator came off with the hose.....did you replace this radiator? It might have been already cracked on the bottom and leaking.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
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'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I do plan on replacing the radiator and all hoses. Good insurance I figure. I am into Saabs as well, and I've heard of more than one engine blowing due to the small hoses bursting that go thru the firewall to the heater core. I'd like to replace these on the "baby" but they are not accessible thru the firewall are they?

You need to remove the screen below the windshield to get to the molded hoses. Steel tubing goes through the firewall. Be good to them, as MB wants a fortune for them!!

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

The freeze plug is on the exhaust side of the engine, and is not hidden.

You said the neck broke off the radiator as you removed the upper hose, and before that, coolant was noticed on the driver's side of the radiator. Doesn't that explain your dump of coolant? The neck cracked, and under operating pressure, spewed coolant. The original radiators were prone to that breakage, and the updates have a metal collar in the neck to prevent cracking.

DS190.....I think the cracked top radiator nipple/neck was a latent problem. Nothing was seen leaking there prior to taking the top hose off. that's the first thing I checked when it was still a small drip The smaller puddle of coolant at that corner of the radiator was a drop in the bucket compared to what was under the intake side of the engine-- further back.

Are you sure that this coolant wasn't coming from the heater connection at the back of the block at the oil filter? I dont think there is another place for coolant to come out under there, unless something is very wrong with gaskets, etc.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

If this were my car, it would be interesting to replace the radiator, fill with coolant, and then drive to see what happens. If it leaks, then replace the hoses to the heater and windshield washer reservoir.

And, you did check the short hose between the water pump and head?