Airlock in the system - Mercedes ML 270 cdi Auto W163 2002

[13enzy]

Hi
The car has been stood for over 6 weeks whilst i was recovering from my operation
When I finally started it, i eventually realised that there was NO Heat coming in the car !
The engine temperature was sitting at less than 20 degrees all the time, the dashboard was at... -2.0 to 3.0 degrees ......so if i was driving, it would be less than 2.0, and if i was stationery with the engine running it may go up to 4.0degrees... (and that is still... COLD)
It was suggested by members that my Thermostat is stuck in the open position, and is faulty and will need replacing
I have replaced the thermostat and the engine temperature is now always around + 87 degrees (approximately), so this means that my previous thermostat WAS in fact faulty, and the old thermostat had a rattle coming from it too.
HOWEVER....However, although the engine temperature has now gone up to > 87 degrees...... nevertheless i am not getting any heat in the car....Please someone help...we are FREEEEEZING !.......As the thermostat has been replaced, i thought it could be an electrical problem, which is not allowing the heat to come through...Hmmmm ...
Please indicate how to bleed the airlock in my system also
Thanks

 

[zipdip]

Well I think you might have a airlock,just remove the radiator cap/header cap and start the car up and let it get warmed up you may well see the air bubble out,it is worth a try,as it does not cost anything to do.

 

[estate-agent]

If it is an air lock then as above, bleeding the air out via the filler cap is usually possible, make sure the heater control in the car is set to hot otherwise the heater matrix will be closed off leaving a potential air lock still in the system. Not sure on the ML but many cars will have some form of bleed nipple (some times more than one) in the cooling system to help expel any trapped air, but chances are you'll get them out via the filler cap. You will need to make sure it gets right up to temperature otherwise the thermostat will be reducing the flow of coolent around the engine. It can take forever in cold weather to get fully up to temperature so I would suggest a run around the block and I normal leave the cap off whilst doing this as it will help with air removal. Once you up to temperature it's a case of waiting and watching, get the fan on to speed 1 or 2 in the car so you can feel the air, don't bother with full blast as it'll just slow down the warm up time of engine, as long as you can feel the air on your hand that'll be ok. When the thermostat opens the water level should drop in the filling reservoir, top up again if necessary. Once you feel hot air in the cabin you're hopefully done Just remember to use an anti-freeze mix if necessary.

If you still get stone cold air then your heater matrix valve maybe stuck / faulty.


.

 

[chrisk2010]

Try what zipdip and estate-agent have suggested i've had a particularly stuborn airlock in my golf and old C class on seperate occasions both taking over an hour to clear by doing the above.

 

[grober]

Unless your cooling system has been drained recently an airlock seems unlikely? What may have happened is the valves that control coolant flow through the heater matrix have seized. There may also be an auxilliary pump on the return side which may have seized/ fuse blown. here's a strip down of the valves on another model--- the ML may be different ??
Howto: Clean the Duovalve

A HOW TO on changing the auxilliary heating pump again for a slightly different model
Mercedes-Benz ML-Class W163 (1998-2003) Technical Articles – ML320 – Pelican Parts

 

[Joderest]

Guy said thermostats replaced, so some coolant will have had to be taken out. I have read somewhere that an air lock can result from this.
Did you replace state yourself or did workshop do it, if workshop, take it back and ask them to bleed system

 

[13enzy]

Guy said thermostats replaced, so some coolant will have had to be taken out. I have read somewhere that an air lock can result from this.
Did you replace state yourself or did workshop do it, if workshop, take it back and ask them to bleed system

hi
i did it myself after flush, and then also replaced with new antifreeze

 

[13enzy]

Guy said thermostats replaced, so some coolant will have had to be taken out. I have read somewhere that an air lock can result from this.
Did you replace state yourself or did workshop do it, if workshop, take it back and ask them to bleed system

Hi
Yes I did it myself