Hi all,

2000 TD5 with 308k and very recent head gasket replacement.

I have been having an intermittent issue with my combo TM2 Low Coolant Alarm going off consistently in the car in the mornings (after sitting overnight) and when I try to go home from work. It appears to be worsening over time.

This has been happening intermittently since I had the head gasket fixed last October. There had been a small amount of coolant getting past the spring clips on the top rad hose to the radiator, which I tried to resolve by changing spring clips, re-seating the clips, using a smaller (or right size?) size spring clip (42 mm). I assumed that the ongoing issue of losing a small amount of coolant by the spring clips was somehow introducing air into the system and causing the alarm.

After having no luck with spring clips, I recently changed over to heavy duty Norma clamps. There is no sign of coolant leakage at the top hose to radiator now, nonetheless the alarm saga continues. The only other suspect place is on the top rad hose bleeding valve, where it may be weeping, or it just could be leftover coolant from repeated bleedings. There are no apparent leaks from any other spring clamps anywhere else.

This morning I had to bleed it 3 or 4 times before the alarm finally stopped. This afternoon the alarm is back and it did not stop even after bleeding it 4x times (no air apparent on any bleed attempt). (I bleed the system by lifting expansion tank and releasing coolant and/or air from bleed valve on top rad hose BTW).

I eventually got sick of this as it was 42c and simply drove it with the alarm going. The alarm remained steady until Nanocom indicated that coolant temp was around 75c, at that point the alarm and red light became less and less steady and eventually stopped altogether about half way home. The alarm did not go off after I re-tested it 90 mins after arriving home.

I have had this reducing alarm occur previously after letting the car run in driveway after repeated bleedings before.

I did an AULRO search and noted that some people had issues with their earth wire, issues with dirty/corroded probes etc. I have confirmed that the alarm turns off when probe wire and probe itself earthed. My probe is quite new (I lost the old one) and it appeared clean - I plan to give it a clean if the alarm is on tomorrow morning. I also saw someone having the issue of the alarm increasing/decreasing while operating.

I also note that some suggest that the alarm going off like this indicative of head gasket issues. I would certainly hope that this is not the case here, although I realise that coolant leaking by clamps may indicate cooling system pressurising.


I was just wondering if anyone else had any suggestions, comments or ideas about what is causing this?


Mark