Help with coolant problem please.

[Eiknujrac]

I drive a 1991 300E, and today i decided to flush the radiator because it has been a couple years.

So I crawl under the car and find the drain plug mentioned in the service cd's (passenger side of engine block), and drain all the old stuff out.

I then use prestone radiator flush to clean out the system, and drained that out.

But when the time came to fill up the resevoir, the system only took 6 quarts. The service cd's and the owner's bible both say it takes 10, yet mine only took 6. I even ran then engine till it was above 80 degrees and ran the heater as well.

Is there something I'm forgetting? Or is there another place I have to drain the coolant from?

And here's the main problem:

When refilling the coolant, assuming the system would take 10 quarts, I went ahead and added a gallon of distilled water first. Not untill i began adding the coolant did i end up filling up the resevoir after only 2 additional quarts. So now the system has 4 quarts of water and 2 quarts of MB coolant, and (something else?) filling up those extra 4 quarts??

I have no idea what to do, any help would be appreciated. Thanks
-E

[Ferdman]

Eiknujrac, you're correct the cooling system capacity is 10 quarts. It's necessary to open the engine block drain valves to drain most of the 10 quarts ... there is coolant in the auxiliary water pump, heater hoses and heater core. Unless you removed the thermostat or ran the engine long enough to open the thermostat during the flush only the radiator, not the entire system, got flushed. If so, I recommend removing the thermostat and flushing the cooling system again. Drain the engine block and radiator. Fill the system with tap water via a garden hose. Run the engine with the radiator cap off, radiator drain valve open and the garden hose in the top of the radiator matching the flow out the radiator drain valve so that the cooling system is full at all times, but not building up pressure. Run the engine for a few minutes until the drain fluid runs clear. Turn the engine off and drain the radiator and engine block and close the drain valves. Refill the system with a 50/50 mix of coolant and water and run the engine with the radiator cap off to evacuate any air in the system. Turn the engine off and reinstall the thermostat. Run the engine until it's up to temperature and check the fluid level in the expansion tank. Add a 50/50 mix up to the full mark and you're done.

[stevebfl]

I'm sure you are also catching all the flush as you pour the water in the top and properly disposing of it. Those silly EPA officials keep telling shops not to do that.

[Hatterasguy]

Why don't you just wait overnight for the engine to cool? It will probably suck some more in, than just top of with coolent. Mine sucked in a little coolent every day for 3 days after I did mine.

[Eiknujrac]

During the flush, according to the instructions on the flush product, i waited until the engine reached normal operating temperature, and then ran the heated on full blast for 10 minutes. I then shut if off, drained the flush, filled it up with water and repeated. During this process i used the drain plug in the passenger side of the engine block, is this the only drain?

[pfphipps]

There is also a drain on the bottom of the radiator itself. Did you open that as well when draining? I did not see where you said you did that.

[sootman73]

i know this is an old thread but is it best to refill coolant without the thermostat in? i'm having trouble getting the system to refill....

the top port broke off the radiator and i'm tring to get by until i can afford a new radiator. there was just enough left to tighten the hose back on but its gonna worry me until i can get a new one. i got the engine up to temp and its not leaking. i slightly opened the plug on top of the thermostat housing and coolant started to leak out so i didn't open it all the way....

should i let it cool and then pull the thermostat and then run it while topping off the expansion tank?

thanks in advance!

[Ferdman]

sootman73, it's best to remove the thermostat when refilling the cooling system to ensure the engine block is filled with coolant. When I had the upper radiator connection break off I simply secured the upper radiator hose to the remaining stub and added coolant to the expansion tank ... no need to remove the thermostat. Until you replace the radiator you may want to try running the engine with the expansion tank cap loose so the cooling system doesn't build-up pressure and cause the upper radiator hose to blow off.

I recommend replacing the radiator immediately. Shop around for the best price on a new Behr radiator. The newer Behr radiators have a metal-reinforced upper hose connector.

[sootman73]

thanks fred. i already bought this one yesterday off ebay.

i thought it was pretty decent. it is a three core which i couldn't find anywhere else. the others were 1 and 2 core so i'm excited about that.