w126 water pump

[aaronsdad1997]

Hello again everyone...yet another question for you all to mull over....How do i check my water pump is working on my 1990 300se w126.
I just changed the coolant but on refilling i only managed to fill the expantion tank...so i ran the engine a little while thinking that the coolant would circulate and i`d top it up,but the coolant in the tank is still there.This doesn`t seem like nearly enough coolant has gone in to me so i`m thinking maybe the pump has stopped working.I have been out on small journeys and run the engine at idle for about half and hour with no overheating issues but am perplexed.As i said,i would have thought it would take more coolant than just the amount i put into the expantion tank.
I would welcome any thoughts,ideas or answers on this...in fact i`m a little worried and a little desperate as i don`t want to run the car and risk engine damage until resolved??? Also is the fan supposed to come on as soon as i start the engine or kick in as the engine heats up???
Many thanks one and all

 

[television]

The water will not circulate until the engine has reach the temperature of the thermostat, around 87-95 degrees. If the pump was not working it would soon overheat on an incline or in traffic, the optimum temp is around 100c and you have the gauge to tell you what is going on

 

[grober]

Did you check how much you drained out?? Did you drain the block as well as the radiator for example? As Malcolm says the full water cooling system wont come into play until the thermostat is fully open. Check this by feeling the top hose when the engine is warmed up it should be hot if the thermostat is open. To help filling with coolant it pays to park the car with a slightly nose up attitude so the radiator/expansion tank represent the highest points in the cooling system. After a refill it helps to do the following--From cold with the expansion tank cap off run the engine and gently squeeze the radiator bottom hose to expel any trapped air. ( WATCH THAT FAN!!) The other possible area for trapped air is the heater matrix but since this is served by a small circulating pump this should rapidly clear.

 

[aaronsdad1997]

Thanks for 2 very very quick replys...It seems all is well after reading them and i am actually worrying over nothing,just my overcautious nature...
Have joined this forum only a couple of days ago and am amazed how friendly an helpful you all are.
No doubt i will be returning with more little problems soon as this is my first foray into the world of vintage mercs.

 

[television]

To make sure that the system is full and no air, take off the filler cap and squeeze the bottom fat hose on the rad, this will force air bubbles out, best done when hot, but do take car if you have an electric fan, as they can start up at any time, even with the ignition off.

Great cars the 126 and welcome

 

[aaronsdad1997]

How would i drain the coolant from the block???

 

[television]

Taking off the bottom hose would empty most of it

 

[aaronsdad1997]

Many thanks,yet another problem i`ve come across while trying to change oil.I found that the sump plug is rounded,any tips on removing a rounded sump plug????
Desperately need help on this one...Thanks in advance

 

[television]

You could get the oil sucked out, many engineers do this.

A small stiltson should move it best done hot, you could try hammering on an odd size socket, but take care as the sump is alli, A cold chisel not too sharp may also do it