Disappearing Coolant - PeachParts Mercedes-Benz Forum

#1 10-02-2002, 10:47 AM

Hi guys, I've been having another weird problem with my Benz. I just had a pinhole leak in my rad fixed, and I have already had a head gasket job over a year ago. but I still lose coolant.

I don't know where else to look. I've been topping it up once a week and I really don't know what else can be done.

Help !

Aaron Rochard

1976 230 W115

Kestas · #2 10-02-2002, 11:09 AM

As you already know, it's gotta go somewhere. If possible try pressurizing the cooling system (15-20 psi) with shop air. This sometimes uncovers leaks that you won't find when the car is standing still.

Take a look at the spark plugs. Look for one that's cleaner than the rest. This would clue you that you're losing coolant through the combustion chamber.

#3 10-02-2002, 02:08 PM

Thanks ! Just got back from the mechanic, (I'm having some brakes and rotors installed) and I noticed a slight leak underneath coming from somewhere on the engine block. I will have to investigate further when I get it down from the hoist.

Aaron Rochard

1976 230 W115

Mike Richards · #4 10-02-2002, 05:25 PM

As stated earlier, the best way is to pressurize the system. Auto Zone and other such places will rent a pressure tester for $75 + tax. You get your money back when you return it. Pressure test the system when it has cooled down. After you pull the expansion tank cap or radiator cap(whatever your case may be), you hook up the tester and pump it up to about 15-17 lbs. If it's leaking it will start dropping pressure and you will see the coolant dripping down below. Now you know where it's coming from. After you think you have it fixed, pump it up again and see if it holds pressure and doesn't leak for about a 15 to 20 min. spanse of time.

#5 10-02-2002, 08:17 PM

Just took a look under the hood and found that the leak seems to be coming from the passenger side of the engine block somewhere. There doesn't seem to be any signs of leakage from the thermostat housing or any hoses that I could find.

Is there any chance it might be a valve or something, or does this sound like a potentially huge problem?

Gulp !

Aaron.

Mike Richards · #6 10-02-2002, 11:14 PM

If it's leaking/seeping from where the cyl. head joins to the block, you could have a faulty head gasket. Is this where's it's leaking from?

You really need to pressure test it to know for sure unless it's a hose in plain sight with an unmistakable problem.

#7 10-03-2002, 08:22 AM

Sounds like a leaking monvalve. I'm not sure if your car has one but I had the same exact problem with my W126. I had coolant leaking from the valve onto the engine and down to the ground. Looked like it was comin right out of the motor. I fixed it by taking it apart and cleaning it. The problem dissapeared! Good Luck!

#8 10-07-2002, 11:33 AM

Just took the car back to the radiator guys that fixed a pinhole in my rad a month ago and they said to me it looks like it's leaking from the head gasket.

ARGGGHHH !!!

I just had it changed 2 years ago, so I don't know what to do. Could it be something botched by the radiator people? (I cleaned and flushed the rad myself after I got it back) or could it be the guys who installed the new gasket in the first place? (they really are Volkswagen mechanics and I wonder if this is something I should have left to a Mercedes shop)

Any advice before I go ahead and get the gasket changed ?

Thanks,

AARON.

1976 230 W115

a2aa · #9 10-07-2002, 06:03 PM

\WHEN YOU said the radiator guys siad... "looks like".. I guess they were never sure, right?? Is the engine heating up 100-110 degrees? Anif not.. have you looked at the basic item ie: RADIATOR CAP? This issue of radiator cap loosing pressure- keeping- qualities always haunts guys that discover a puddle of anitfreeze right under the front passenger side of the car. The reservior is on that side , right??? Worth the check, dude
Good Luck

a2

#10 10-17-2002, 04:08 PM

Just got some grim news from my mechanic. he tested the pressure and it turns out the coolant is dripping from the head/gasket area in the middle of the block on the passenger side.

He has to take the head off and see what it might be. I can't see how it would be the gasket, as I had them change it just 2 years ago and I haven't had any serious temperature problems recently that may have caused the head to warp.

The only thing unusual that I did recently, was take a long drive (about 3 hours each way) to a friends cottage and I've never driven it that far before. Furthermore, it didn't show signs of leaking until about a week after the trip.

Anyone have any potentially good news for me before I dig deep ?

Thanks,

AARON ROCHARD

1976 230 W115

#11 10-24-2002, 03:48 PM

Well, I went and got my mechanic to open up the engine and it turned out to be just the gasket. He said he's going to show me where it burned out (just on the passenger side of the engine block) He said that it was a strange place for it to go, but thankfully it'll be a lot less than if it was the head itself.

Thank you all for your help and advice.

AARON ROCHARD.

1976 230 W115 Back in business !!!

a2aa · #12 10-24-2002, 03:51 PM

---glad it was only the gasket

a2