[bfaone]

M47 320d e90 2006 odometer 130105 miles ...
It started by engine over heating.
Coolant circultion was sun-optimal , air in system.
I opened the mechical coolant pump, It looked fine since it was only replaced 6 months ago. I replaced it again along with a new thermostat. Also changed the AGR thermostat.
I have been UNABLE to get the system Rid of the air..........
Despite my best effects......
Opened the hoses and flushed the radiator.... Fine
Disconnected the heating pipes ,,,, flushed them with tap pressure... FINE
( Heater has become highly unreliable ,,, most of the time DOES NOT WORK ??)
CAR Heats up and coolant is expressed frm the safety cap of coolant reservoir.... Checked even Replaced.....Fine

Radiator FAN kicks in always at 97C ... Fine
Blows air which is COLD !!!!! Pump not circulating ????

TOOK out Thermostat from the Thermostst body , so it does not need to open at 87C for water to circulate through radiator...... No improvement in pump function, No steady flow falling into coolant reservoir...

HAVE TRIED AGAIN AND AGAIN BUT THE AIR KEEPS OF ACCUMULTING IN THE SYSTEM .... IS THAT NOT THE REASON FOR THE INABILITY OF WATER PUMP TO PUMP ???



PLEASE HELP........

[Daviebrown]

Check the heater control valve, it's possibly stuck closed trapping air inside the heater circuit. Have you got a code reader?

[bfaone]

I have INPA as well as ISTA
I have flushed the heater by directly connecting a mains water hose pipe. So there should be no air trapped there.
Also , recently noticed water being flushed out of cap of coolant reservoir, too much pressure generated ?????
It's because of air being sucked into the coolant circuit ,, from where. ??????
Or it it headGaskit ????
Any ideas .....

[Daviebrown]

Have you checked the additional water pump part number 64 11 8 369 806 on realoem.com? Also the heater control valve or the changeover valve 64 12 6 951 814 if you have independant heating, either way your diagnostic should throw a code

[bfaone]

I have no diagnostic codes related to coolant / pumps on ISTA D
Also, I bye passed the cabin heating and additional axillary heating pump to make sure they are not the cause.
DID NOT CHANGE A THING...so re-connected them back in circuit...

[Daviebrown]

Then i would recommend what is described as a sniff test where the coolant is tested for hydrocarbons, basically its a non invasive head gasket test.

[therealdb1]

Originally Posted by bfaone

Also , recently noticed water being flushed out of cap of coolant reservoir, too much pressure generated ?????
It's because of air being sucked into the coolant circuit ,, from where.

It is unlikely air will be sucked into the cooling system as your pumps will not generate enough suction to overcome the hot water pressure above atmospheric to pull air past the seals.

If you have water blowing out of the expansion tank you have either:
a) Too much water in there to start with.

b) An air lock or other blockage somewhere causing excessive pressure. You say you bled the the heater matrix and bypassed the heater valves and separate pump but did you fill and bleed the system properly? On the petrol engine there are certain bleed screws that need to be opened and the coolant pump needs to run for 12 minutes with the heater on full blast to effectively fill the system. I assume there is a similar procedure on the diesel but I do not have a manual for oil burners.

c) The system is being pressurised perhaps by a failed head gasket. You will need to get a compression check or sniffer test done but I would expect other symptoms of poor drivability if this were the case as at least one cylinder will not be giving you the full bang for your buck.

A later thought. Did the thermostats you replaced have a giggle pin or equivalent? These should be placed at the highest point to allow air to pass even when the thermostat is closed.

[bfaone]

Thank you everyone.

I have opened up the head and am going to put a new head gasket and new oil stem seals for valves.
Waiting for spare parts from Autodoc .......

There did not seem to be any other cause as I have properly and meticulously purged the coolant of air but lately there was buttles coming up in coolant reservoir....
And pump was erratic off / on poorly pumping...
Thank everybody

[bfaone]

Day 2 after refitting a new head gasket.
Everythings seems to work EXCEPT that high pressure sensor signal failure 3F30
there is check engine light on.
Car is starting OK.
Took Five long selfs yesterday before it started, I thought , thats it , its never going to start !!!!! I might have messed it up !!!

Thanks God it started !!!
Today again tried different things to sort out the sensor error, its not going away !!!!

[Daviebrown]

If the code reads signal failure then there is a possibility that the plug on the front end of the fuel rail is not connected properly, or the sensor is faulty, Have you tried to clear the code ?. if so have you tried to clear the code after it started up? you have obviously lost the pressure from the fuel rail by removing everything to lift the head and that's why it took such a long time to start the first time after re build. you can often get a low fuel rail pressure code when restarting following a strip down but that wouldn't be a signal failure, check out the rail sensor plug first then report back. I've got both fuel rail sensors if you want to buy them drop me a PM.