I am trying to track down a coolant leak. It is coming from the driver's side of the engine, under the intake manifold on the M104 engine. The coolant is dripping with a cold engine with no pressure in the tank or radiator.

I cannot actually see where the coolant is leaking because of the intake manifold and other components in the way. The picture that I have attached is of the '95 E320 M104 engine. Does my G320 have this coolant connection? This might be a starting point for hunting it down. 
 http://mercedes.braingears.com/124_DISC1/Program/Engine/104/20-2300.pdf

Thanks in advance...

G4Garret - 4/29/2006 2:27 PM My experience is that when a v-belt breaks due to age, it just snaps and falls off. When they become shreaded, burnt and wrapped up on things, it's a an indication that it's not the belt's fault, but rather that the belt tried and tried, hung on to the very last second sacrificing itself while trying to do it's job. I would be looking for a bad bearing on the pully the belt was wrapped around. Evidence to analyze might be: Did the belt squeal at all prior to "breaking"? If the belt was wrapped around the water pump, perhaps it's bad. Is the truck cooling ok? Is that pump pumping water and spinning it's cooling fan ok? Is the pump leaking coolant ouf ot it's emergency seal/bearing drain hole under the pump bearing area? that's a sure sign the seal and/or bearing has failed. Regardles, if water is comming out that little hole, the pump is doomed. Does the pump turn easily by hand? Does it squeak? Wobble? feel gritty when turned by hand? Between this and your other post, I don't think there could be much more evidence pointing to a bad water pump, unless it falls right off the motor too. A decent mechanic should be able to determine this in seconds. Just my experience. But heck, you never know. Strange things do happen. Garret

There was no squeaking prior to breakage. The truck is cooling properly, and nothing felt wrong with the pump when I was changing the belt. I have been out of town and not looked at the truck or engine for the last 4 days. I should have a little more time this week....

I had to replace the water pump this week. While I was at it, I replaced the thermostat and most of the hoses too.

When I removed the old water pump from the truck, I took it down to the local dealership and compared it with all of the other M104 pumps. It did not match any of them. Luckily when I called Steve at EuroTruck, they had one in stock. I got the lower radiator hose from EuroTruck, but I got the rest of the hoses locally.  

It must have taken me twice as long to remove the pump as it took me to reinstall the new one. I guess I learned all of ins-and-outs while I was removing it. I used a torque wrench for everything when I was putting it back together. The bolts requires a lot less torque than you would use instinctively.

While I was waiting for the pump parts, I removed the valve cover and re-torqued the head. Fortunately, none of the head bolts were loose. I also replaced all of the plastic vacuum tubing in the head and around the front of the engine. The old stuff was getting pretty brittle. Just performing preventative maintenance while I had part of the engine apart...

I ran the engine for about an hour so that it would run at temperature for a while. During that time, the temperature never went above 87'C (thermostat setting). I was waiting for the front aux fans to turn on (to test the thermostat senser that I installed), but it never got that hot.

No more leaks...

That does not look right...

I would go to your local dealership or parts store and purchase a new thermostat. In the box, it should come with a rubber o-ring (I do not know if the older models also used a gasket material). By the looks of it, I would also purchase three new bolts. I would then re-assemble the thermostat properly. Remember that you should only apply 10Nm torque (which will actually seem pretty light).