coolant bleeder valve for 1990 190E 2.6L
 

Hi there....my first post here....

I did do a search on this forum and found some important/useful information regarding changing coolant and draining it from the system. But i was not able to find something specifically for my car. I know i have air trapped in my coolant system, and i wanted to know if anyone can tell me where the bleeder valve is....

thanks in advance.

There is no bleed valve that I am aware of. A bleed line routes from the top of the water outlet to the supply tank. Fill the system slowly until the level stabilizes in the tank a couple of inches below the cap opening and start the engine. Leave the cap off. As the engine warms up the level will drop as the system bleeds. Add coolant as required.

My experience is that the system easily self bleeds.

Duke

i was beginning to think the same until i read in the manual that there is a drain plug on the right hand side of the engine block. But the manual has no picture or description of how to get to this drain plug.....sigh

The block drain valve (which is not a bleed valve) is under the rear exhaust manifold and can be opened with a crescent wrench. Attach a hose to the nipple for spill free draining. The radiator drain also has a nipple for a drain hose.

Daimler Benz made it very easy to change coolant on the M103 engine.

You can also flush the system by removing the heater supply hose at the left rear of the head to flush both the block and heater circuit.

Duke

thanks for that...i needed that specific information.

You are probably referring to a statement I made in this thread: http://www.peachparts.com/shopforum/showthread.php?threadid=97875, specifically, "As to bleeding the air from the M103 engine, if you want to be fussy, you can remove one of the blank plugs next to the temperature sensor on top of the cylinder head towards the front on the inlet manifold side. You can then fill it until coolant appears at this opening. This way you know the block and head water jackets have been filled. It does not guarantee that there won't be air trapped elsewhere though (eg. heater)."

There is not a bleed valve as such, simply several tapped holes into the water jacket in the top of the head. Some of the holes are used for sensors etc and one is usually fitted with a blank plug. It is easy to remove this plug (don't lose the washer) when filling with coolant. Being at the highest point of the water jacket on the engine ensures that no air is trapped in the water jacket. I generally fill mine with this plug removed but obviously others find it unecessary to remove the plug. As to why I do it this way, I seem to recall reading it as a recommendation in a workshop manual.

I too bleed air from this screw that Greg speaks of whenever I flush my coolant system.

I believe your '90 103 engine has it. I do know that older MY 103's had the thermo-valve in this spot but was subsequently moved to the fender wall.

Good luck

The CD manual says to leave one of the caps off as you pour coolant into the reservoir. Stop filling when coolant comes out of the hole. Cap the hole and fill the reservoir to the appropriate level. Get engine to operating temp, check coolant level, etc.

Sixto
95 S420
87 300SDL

hey thanks a lot guys, i was finally able to get about 10L of coolant into the system with a little patience.

Thanks for all the thoughts.......