low coolant warning fix

[shogun]

found this on an E36 forum, but may also be applicable to 5 series:

Experienced that also although coolant leven is fine?
In case you already have changed the coolant level sensor, cleaned the plug and the contacts,checked for air bubbles, measured with your multimeter the wires to check for broken wires and still the warning comes up on occassion, read on what I found on another board, even confirmed by some more E36 owners......

worth to copy that:


Quote:
Finally fixed my "Check Coolant Level" warning while shutting off the engine. Like most others, I tried all the usual fixes that were posted on various groups with no success. Recently while replacing the thermostat I noted that inside the expansion tank there is what I would call a siphon tube that the small bypass hose from the radiator attaches to on the expansion tank. It broke off internally and was loose inside the tank. I ordered a new tank from the dealer and installed it. After the usual bleeding of the system, the check coolant level warning during engine shutdown had finally been fixed. My theory being that the cooling system could not be bled properly because of the broken tube. The air in the system was trapped because air would be drawn back into system through the broken tube. Normally the tube would extend below the coolant level in the tank and during bleeding the trapped air would be purged and not drawn back into the cooling system. With the tube broken or cracked air is drawn back into the system displacing coolant. While the car is not running the coolant level appears good but during driving the coolant drops as the air in the system circulates with the coolant. This trips the OBC and the warning comes on after shutdown. So check your expansion tank for this possible problem."

have to check that also on my M3, already cleaned plug and pins.

[genphreak]

Class catch, thanks- I'll check this on mine and report...

[alex 1993 525i auto]

In my case, after changing level sensor which didn't cure the issue, the fix was to bend a little bit the pins that goes in the connector of the sensor, it was sometime not making good contact apparently. Never seen back that message since three years now. But good info to know about the tube in the expansion tank, thanks!

[shogun]

Alex,
in case the pins do not fit exactly into the plug, the outer plastic surrounding of the pins is broken. Then the pins are bare metal and retract from the plug often, not only in case of this problem. Same applies to headlights, aux fan plug, etc.
Cheap fix: take the pins till they have the thicker diameter they should have to fit snug into the plug without slipping back.
Final, but more expensive solution: buy from BMW the new pins with attached short wire and solder in a new pin. They are even watertight. I bought all sizes of the pins.
Here
http://www.realoem.com/bmw/showparts.do?model=GC81&mospid=47354&btnr=61_1296&hg=61&fg=15&lang=enUS
01 Snap-in receptacle 2.5 watertight 0,5-1,0 MM² 61130007441 $5.53
01 Snap-in receptacle 2.5 watertight 1,0-2,5 MM² 61130007442 $5.75
02 Circular contact 2.5 watertight 0,5-1,0 MM² 61130007443 $5.18
02 Circular contact 2.5 watertight 1,0-2,5 MM² 61130007444 $5.43
03 Snap-in receptacle 2.5 watertight 0,5-1,0 MM² 61130007445 $5.58
03 Snap-in receptacle 2.5 watertight 1,0-2,5 MM² 61130007446 $5.80
04 Snap-in receptacle 2.5 with cable 0,5-1,0 MM² 61130007449 $2.07
04 Snap-in receptacle 2.5 with cable 1,0-2,5 MM² 61130007450 $2.32
05 Circular contact 2.5 with cable 0,5-1,0 MM² 61130007452 $2.07
05 Circular contact 2.5 with cable 1,0-2,5 MM² 61130007453 $2.35
06 Snap-in receptacle 2.5 with cable 0,5-1,0 MM² 61130007470 $2.27
06 Snap-in receptacle 2.5 with cable 1,0-2,5 MM² 61130007472 $2.55
07 Snap-in receptacle 2.5 ELA with cable 0,75-1,0 MM² 61130007569 $2.27
07 Snap-in receptacle 2.5 ELA with cable 1,0-2,5 MM² 61130007571 $2.65
08 Circular contact 2.5 ELA with cable 0,75-1,0 MM² 61130007570 $2.32
08 Circular contact 2.5 ELA with cable 1,0-2,5 MM² 61130007572 $2.65
09 Snap-in receptacle 2.5 0,5-1,0MM² 61131376202 $0.98
09 Snap-in receptacle 2.5 1,0-2,5MM² 61131376204 $0.98
09 Snap-in receptacle 2.5 2,5-4,0MM² 61131376206 $0.98
09 Terminal socket 2.5 2,5-4,0 MM² 61138352926 $0.42
only in conjunction with
-- Grommet 61138352924 $0.28
10 Snap-in receptacle 2.5 1,5-2,5MM² 61131376224 $0.50
11 Circular contact 2.5 0,5-1,5MM² 61131376191 $0.55
11 Circular contact 2.5 1,0-2,5MM² 61131376193 $1.12
11 Circular contact 2.5 2,5-4,0MM² 61131376195 $1.05

http://www.realoem.com/bmw/showparts.do?model=GC81&mospid=47354&btnr=61_0522&hg=61&fg=15&lang=enUS


I have replaced >50% of all plugs in my car and also those pins wherever possible. Have a large box with all these plugs and pins and connectors. Whatever you need, I have it, even some which are not available from BMW anymore or never have been, such as for example the plug for the oil level sensor, that I bought from Bosch.

[genphreak]

I want one of those boxes too... i face connector hell every time I do something!

[shogun]

genphreak:

Could it be that Australian version E36 do not have a level sensor? Read this from another forum:

Location: Sydney, NSW, Australia
Car: 1991 E36 BMW 320i

Coolant Level Sensor install on car which came without this feature?

Gday,
Is it possible to install/retrofit a coolant level sensor on a car that didnt come with the coolant level sensor from factory ? What light comes on in the instrument cluster? I dont have the computer check system.
Cheers
----------------------
my car doesnt have the check system
------------------------
I just checked out my car. Where the level sensor goes it has a screw plug to cover that hole. My car doesnt have that fancy computer in the centre console as well. I dont mind checking the coolant level as I do it quite often. I just worried that im going to damage something by unscrewing the coolant cap off and on. I also cant see the coolant level on the outside of the tank


Apart from this I found in the TIS:
Low coolant level Complaint: Cause: Affectedne vehicles: VK-23/Seyfried Baugruppe/Group: 17 17 01 97 (264) All countries 09/1997

Low coolant level
E36, E38, E39 with M52 engine

Complaint: Repeatedly having to top up with coolant, high reading by coolant temperature gauge, possibly Check Control display "Check coolant level".

Cause: During the manufacturing period stated below, original filling of the cooling systems at the factory was carried out according to the coolant level and not the amount of coolant.ne In addition, due to the glycol concentration of 50% used today instead of the 40% that was previously used, the air still in the cooling system only escapes between approx. 1,000 to 2,000 km (glycol binds any residual air). This leads to the coolant level in the expansion tank dropping. ne During this phase, you may find that the area around cylinder 6 becomes smeared due to coolant sweating out of the engine.ne This smearing occurs due to settling of the cylinder head gasket during the running-in phase of the engine. Once settling of the cylinder head gasket has ended, you will usually find that no more coolant escapes in this way. This process can lead to the above complaint from customers.


Nevertheless, the cylinder head gasket may in isolated cases still cause further sweating of coolant after the running-in phase.
Due to this slight sweating, it is not possible to check the cylinder head gasket for leakage by means of a CO concentration test on the coolant (using a CO leak tester).

Affected vehicles: E36, E38, E39 with M52 enginene Manufacturing period: September 1995 to March 1997

Procedure: If after talking to the customer, you find the complaint described above is clearly a valid one, the cylinder head gasket must be replaced.


If the above complaint is received, carry out the actions described below. Action before replacing the cylinder head gasket in accordance with the Repair Instructions:
see Repair Instructions 11 12 100.
Check for traces of coolant on the exhaust side of the crankcase in the area of cylinder 6.
Important note on how to fill the engine with coolant:
see Repair Instructions 17 00 005.
In the E38 and E39 with M52 engine, both vent screws (on the expansion tank and on the thermostat casing) must be loosened.
The following additional instructions have been added to the Repair Instructions:
- Turn on the ignition before filling the engine with coolant.
- Set the heating control to maximum temperature.
- Set the blower to a low speed.
In this way, the heating valves are opened and the auxiliary water pump runs (if fitted).
Pour in the coolant slowly.
Observe the coolant mixture ratio glycol : water of 50 : 50.
Bleed the coolant system.
See Repair Instructions 17 00 039.
In vehicles fitted with a latent-heat accumulator, follow the special bleeding routine specified.
See Repair Instructions 64 12 ...
In vehicles fitted with independent heating, follow the additional bleeding routine.
See Repair Instructions 64 12 ...
The coolant mixture ratio (glycol : water) of 50 : 50 must under no circumstances be exceeded. Reason: An impermissibly high concentration of glycol binds any residual air still in the cooling system, thus delaying elimination of the residual air during engine operation.ne Moreover, the thermal conductivity of the coolant is reduced as the glycol concentration increases. However, if the mixture ratio of 50 : 50 is not adhered to, with more water than glycol being poured in, the level of corrosion protection over the 3-year change interval specified is no longer guaranteed. Guide values for measuring the concentration: glycol : water = 50 : 50 corresponds to anti-freeze protection down to - 40 ° Cne glycol : water =
40 : 60 corresponds to anti-freeze protection down to - 30 ° C