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· Registered
1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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9,176 Posts
My 1983 had a coolant leak that I could not see where it was coming from
other than see coolant on the bottom of the Engine. Turned out that it
was leaking at the Coolant Pump and had to be replaced.
Have to remove the Distributor to get access.

My over-active worst case imagination at first thought it might be cracked block.
Fortunately that was not the case.
 

· Registered
1982 380SL
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68 Posts
Discussion Starter · #4 ·
Nice, now I'll be paranoid that I have a cracked block until I have time to dig in and check it out! What's the best way to diagnose the failed pump if that's the problem? Can I at least see it without removing distributor.
 

· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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35,282 Posts
Can anyone give me any ideas on where this coolant is leaking from? I'm attaching a photo, hope it helps!
Liquid follows the path of last resistance governed by gravity.

Sometimes you can get lucky and spot it right away. But the drop or puddle might not have come from directly above.

You'll have to look and feel around.

Or buy a coolant system pressure pump OR put in some coolant dye and use a black light. This too can be bought in a kit.

How old are your hoses? Have you tried tightening all the clamps? How many miles on the waterpump?
 

· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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35,282 Posts
One tiny drop.? I don't get the concern.
A drop of oil coming off my engine doesn't concern me. A coolant leak would stop me from driving until corrected......they can become worse in a blink of an eye.
 

· Registered
1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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9,176 Posts
One tiny drop.? I don't get the concern.
According to many that is the wrong color coolant.

wbjdmd, if you are new here you might not know that Mercedes antifreeze
is yellow in color and some "purists" here think that you must use
yellow colored coolant in these Mercedes. Lot of discussion here as
to the proper antifreeze to use. Personally, I run Mercedes yellow
in my 380SL, and Prestone green in my 560SL.

When my water pump started leaking in my 380SL, it started as a small
leak but it only took a few days for it start leaking a lot. Hopefully yours
is just a rubber hose. There is a 2 inch rubber hose that connects the
water pump to another part of the engine - look down in there. If I had
to guess, its probably your water pump.
 

· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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35,282 Posts
It used to be yellow. Its now blue.

See the article. It answers all you questions about Blue, Yellow, and Green as well as distilled and demineralized water.
I got tired of talking about it.


This should be in the EGv107.
 

· Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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13,842 Posts
Can anyone give me any ideas on where this coolant is leaking from? I'm attaching a photo, hope it helps!
A leak at the front of the engine often gets blown back and it then trickles down and drips off a low point.

There is a drain hole on the underside of the cooling water pump, just behind the pulley. Put your finger under there and see if it comes away with any antifreeze on it. Or use a mirror.

Another source I have had, is from coolant hoses - check carefully around all clamped connections on engine and on radiator.

By the way, I too am using green coolant on my 107 and 123 and have done for 25+ years. The brand I usually buy is said to be compatible with aluminum. I tried to change to Zerex G05 on 107 when I had water pump changed, but shop, I think, put in regular Zerex green. I think it is good so long as it gets changed every 2 or 3 years. I do use MB coolant on my W210 (and presumably dealer serviced GLK)
 

· Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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14,316 Posts
A leak at the front of the engine often gets blown back and it then trickles down and drips off a low point.

There is a drain hole on the underside of the cooling water pump, just behind the pulley. Put your finger under there and see if it comes away with any antifreeze on it. Or use a mirror.

Another source I have had, is from coolant hoses - check carefully around all clamped connections on engine and on radiator.

By the way, I too am using green coolant on my 107 and 123 and have done for 25+ years. The brand I usually buy is said to be compatible with aluminum. I tried to change to Zerex G05 on 107 when I had water pump changed, but shop, I think, put in regular Zerex green. I think it is good so long as it gets changed every 2 or 3 years. I do use MB coolant on my W210 (and presumably dealer serviced GLK)
If you read the article you will see the green stuff is suitable for cast iron blocks and copper and brass radiators which is what you have in your 107 and 123. But it does recommend the change every 2 to 3 years.
 

· Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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13,842 Posts
If you read the article you will see the green stuff is suitable for cast iron blocks and copper and brass radiators which is what you have in your 107 and 123. But it does recommend the change every 2 to 3 years.
Even on our early 107's, we do have some aluminum wetted parts. Cylinder heads & water pumps for example. On my '72 I did notice some pitting under the gasket on the thermostat housing. Had to do a JB-WEld repair. Part of reason I tried to change tp Zerex G05. I believe W123 also has some aluminum wetted parts - I think rad core may be aluminum.

The owners manual for our 72, says to use water as coolant with a few ccs of corrosion inhibitor added. They were apparently filled with some type of antifreeze at the factory. Presumably, back then, some type of ethylene glycol mixture like the green stuff.
 

· Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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13,842 Posts
In rereading Roncallos link:

The blue G48 and the yellow G05 MB coolants are compatible. But when you mix them, the resulting mixture is GREEN :)

According to basic color theory, mixing the new blue with the previous yellow-tinted formula in equal proportions will produce a nice green. They are completely compatible.
 

· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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35,282 Posts
In rereading Roncallos link:

The blue G48 and the yellow G05 MB coolants are compatible. But when you mix them, the resulting mixture is GREEN :)
Gee whiz!

You are right again!
 

· Registered
1982 380SL
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68 Posts
Discussion Starter · #16 ·
I'm back on this issue. The leak has gotten worse. It started as a couple of drops and now after running or when the barometric pressure changes it will leak from 1/4 cup to a cup of coolant. I check all of the hose connections I can see and they seem to be tight with no leaks. Maybe leaking at the bottom of the water pump? Any good way to check this? How hard would this be to replace? I have no service records but it looks factory. Any advice would be appreciated!
 

· Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
Joined
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13,842 Posts
I'm back on this issue. The leak has gotten worse. It started as a couple of drops and now after running or when the barometric pressure changes it will leak from 1/4 cup to a cup of coolant. I check all of the hose connections I can see and they seem to be tight with no leaks. Maybe leaking at the bottom of the water pump? Any good way to check this? How hard would this be to replace? I have no service records but it looks factory. Any advice would be appreciated!
Post #11 , 2nd paragraph.
 

· Registered
1972 220 D, 1974 450SL, 1995 E300D 2002 S430, 1976 300D, 1986 SDL, 1982 SD
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2,728 Posts
Your water pump has now failed fully. You will need to replace the pump, which will have new gaskets that will take care of the leak. You may also find that there is a bunch of calcium built up on the pump body. That will show if you need an acid flush to cut through the crud in the rest of the system.
 

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1982 380SL
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68 Posts
Discussion Starter · #19 ·
I ran a bottle of Bar's Stop Leak and it has quit leaking.(for now). Hope to get it to the shop soon for check and decide if this car is worth doing major repairs like replacing the water pump. Idle is rough once engine warms up(only warming to around 80 C at idle), is this related to failure of the water pump?
 

· Registered
1975 450sl
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121 Posts
You should chase the hose connecting your reservoir to the radiator.. Attaches with hose clamps on both ends.. If you recently did a flush, you should of checked and removed your reservoir to make sure its not cracked. If its solid no cracks.. Check the rubber hose throughly there and remove it.. It can be clamped too hard and could puncture where you tightened your clamps. I used new spots on the hose for tightening. Do a flush if you haven't yet.. Check your hoses and reservoir.. Then go underneath and spend 5 minutes watching to make sure there is no leaks.. If after all that you still have a leak.. May be coming from another hose. Check them all
 
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