Mystery Coolant Loss ... - 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

autozen · #2 10-02-2002, 11:09 AM

AAron,

You probably have a slightly loose clamp somewhere, and the only way to properly check the system is when it is stone cold. Once the engine is cold, install a pressure tester to the filler neck. Pump it up to about 100 kilopascals and watch.The leak should appear after a few minutes. If you find a loose clamp and want to test my instructions, don't touch the clamp. Warm the engine up, shut it off, put the pressure checker on and wait. As soon as the engine cools down, the leak will appear.

Good luck,
Peter

#3 10-02-2002, 02:09 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

#4 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.

psfred · #5 10-02-2002, 09:04 PM

Aaron:

Find and check all the heater hoses.

Most likely you have a bad heater hose or heater pipe -- there is usually a long steel pipe that connects near the water pump or thermostat, routed under the AC compressor, that connects with a rubber hose at the heater connections. A leak here will show up on the block when it drips off.

The hose between the water pump and thermostat housing can be a problem, too. Impossible to replace with the AC on, you will have to take the bracket off. You will need to make some studs (cut the head off a bolt the same size as the bolts that hold the AC bracket and water pump on and cut a slot in the end so you can turn it with a screwdriver) and then replace the AC bracket bolts with them to keep the water pump on when you pull the AC bracket. Details if that is the problem.

It is also possible that one of the core plugs is leaking. This isn't a major disaster, but can be a huge pain to fix as the plug screws in and will be STUCK after all these years.

Don't panic yet, I've never heard of a block cracking and leaking like that unless if was frozen hard with no antifreeze.

Peter

#6 10-02-2002, 09:58 PM

Thank you so much !!! I think that sounds about right. I will remove some things in the area to get a better look, but I have no A/C condenser in there (but that area is still a little cramped) I'll order the parts if I can, because I'm making a trip down to Buffalo this weekend and I'm afraid something might go.

Oh well, thank God for CAA !!!

Aaron.

#7 10-07-2002, 11:35 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

autozen · #8 10-07-2002, 11:51 AM

Aaron,

I've already posted the proper procedure to follow. During my 30 some odd years as a professional MB mechanic this procedure has never failed me. You will find the leak and save the mental anguish. The 230 engine never displayed any outward symptoms of a head gasket leak as I recall. If you have the Stromberg 175 carbureter on there, there are small cooling hoses going to the choke housing that could leak and run down the intake runners making it look like a head gasket.

Peter

#9 10-07-2002, 11:54 AM

Thanks Peter, I will mention the procedure you've outlined to my mechanic. He is going to test it tomorrow.

Thanks,

AARON.

#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

autozen · #11 10-17-2002, 08:03 PM

Aaron,

Many patients have sought another opinion in the medical profession. I don't see why the same rule shouldn't apply here. If you have been factual in your statements, I can't see why the head gasket has failed. I was factory trained and have been a MB mechanic for over 25 years, and I have a hard time believing this one. I think you should seek a second opinion. If you were in Northern California, I'd check it pro bono just to know.

Good luck,
Peter

#12 10-24-2002, 03:47 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 !!!