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  #1  
Old 10-20-2019, 10:49 AM
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Strich Acht
 
Join Date: Aug 2018
Location: Istanbul / Vancouver
Posts: 268
W115 240D - trying to identify where a coolant leak is coming from

Hi,

My '74 240D has developed a bit of a leak and I'm having a little trouble figuring out exactly where it's coming from.

It only leaks when the car is running. It's a drip every 2-3 seconds. I had the car on jack stands and had a look around underneath yesterday and I can see that the leak is making its way down from here:



So, I'm assuming it's running down from whatever is above this but I can't quite see where exactly.

Anyone know what is above this, or what the likely culprit is?

Thanks!

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  #2  
Old 10-20-2019, 11:51 AM
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The only thing which I can think of on the left hand side of the OM616 would be the heater hose feed from the cylinder head. Have you recently changed over to heat setting on your dash slider levers? It is not unusual for the water flow control valve (the three hose valve on the firewall) to leak after a long period of non-use.

They are rebuild-able. A bit of cleaning and a couple of O-rings is all it usually takes.
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  #3  
Old 10-20-2019, 02:26 PM
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Strich Acht
 
Join Date: Aug 2018
Location: Istanbul / Vancouver
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Sounds like a good avenue to explore, thanks for the suggestion. I don't drive the car daily (more a couple of times a week and it's just been off the road for a couple of months). Weather is getting colder up here now so yes the heating has been adjusted. I'll explore that.

If I changed the heating back, would the leak miraculously stop (assuming this is the problem)?

Thanks again
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  #4  
Old 10-20-2019, 04:58 PM
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Got my fingers crossed for ya!
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  #5  
Old 10-20-2019, 10:53 PM
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No Dumping
 
Join Date: Jul 2007
Location: Southern Oregon Valley
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Quote:
Originally Posted by Mike D View Post
The only thing which I can think of on the left hand side of the OM616 would be the heater hose feed from the cylinder head. Have you recently changed over to heat setting on your dash slider levers? It is not unusual for the water flow control valve (the three hose valve on the firewall) to leak after a long period of non-use.

They are rebuild-able. A bit of cleaning and a couple of O-rings is all it usually takes.
If the valve has been changed within the last 10 years or so, it will be all plastic, so I'm not sure that these can be fixed like the originals can be. The good news is that they are relatively inexpensive. In Barbie's words, "life in plastic, it's fantastic".
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  #6  
Old 10-21-2019, 12:10 PM
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I look for leaks like this in the dark with a small flashlight. It only lights up a small area at a time and the coolant, or oil, will usually reflect differently than the surrounding material.

You might not spot the exact leak this way but you can narrow it down to a small spot to look at closely in the daylight.
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  #7  
Old 11-03-2019, 09:11 PM
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One of the generic ways to look for coolant leaks is to pressurize the system. The typical kits have a hand pump with a gauge an adapter cap that replaces the radiator cap. You pump to increase the pressure and hope that pushes coolant out of the leaking area.

We are not talking about a lot of pressure to do that.

Anyway the advantage is you don't have to run the Engine and get your hands up in places to see if you can feel where the leak is coming from.
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Old 11-03-2019, 09:41 PM
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Get a cheap uv dye kit and you can pinpoint the leak quickly.
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Old 11-04-2019, 10:14 AM
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Originally Posted by Jbyron View Post
Get a cheap uv dye kit and you can pinpoint the leak quickly.
New info to me. Thanks.
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  #10  
Old 11-04-2019, 03:48 PM
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Get a rad pressure tester and you will find the leak quickly.

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