Red-Line Temp Gauge and Cold feet!

[modustollens]

I have been noticing that no heat will come out of the cab heater unless the 2.8td engine is over 1000 rpm. At idle it spits out cold air. The engine temp gauge would be at 1/4 or below.

Now, this morning on the way to work, the temp gauge went all the way to the top into the red yet I could get no heat out of the heater.

I was thinking - at -1 C my engine is overheating after running all of 10 minutes! I opened the bonnet and the radiator is cold to the touch and there is not excessive heat coming off the engine block. So, I do not think that the engine was in fact overheating.

Perplexed I am; what to do?

Is the thermostat faulty and not opening? Bad radiator cap? Or is this some electric sensor failure?

I have been reading threads here and looking at the manual. Some talk of faulty radiator caps (keeping coolant system pressure too low); some talk of failed thermostats.

Taking the thermostat out of the engine is no small task for me to do at the side of the road, in the cold. Replacing the radiator cap - as some suggest - would that help?

I know there is an engine temp sensor and coolant sensor:

http://www.imagerocket.net/photos/1351580025_engine.jpg

I will see if these are loose.

Any suggestions about the best way to proceed given my limited skills and the almost total absence of easily replaceable parts? What test procedure would diagnose the problem? How about a good tap to the thermostat housing?

Any help would be appreciated!

Of course - the race is on: the winter is coming - temps below -40C! (-8C overnight low is already here). We should start a betting pool: at what temperature will I no longer be able to get, and keep, this thing running?

Obviously, I can't run without cab heat to keep the windows clear and me from freezing to death. So, this cab heat problem is major, not minor.

During the summer the engine was getting really hot - and I believed the temp guage at that time given that outside was around 35; I hosed all the dirt and dust in the radiator fins to great effect. And I went to one garage with my translator asking them to flush the coolant system out and refill - but they refused to do it! Odd - easy money (and foreigners here always pay more than a local would).

Maybe I should flush the system out myself and see if that helps?

Thanks,

MT

[snewin]

My 2c - thermostat. I've never been known to be correct though.

[threedogs]

Do one mod at a time to eliminate the problem, I'd start with the thermostat

[choppie]

Presume you are using a good anti-freeze coolant, have known radiators to freeze at -2c without the right anti-freeze,
suggest let motor warm up for 10+ mins before driving if not already doing so, Good luck mate, let us know when it gets Cold LOL.

[Clunk]

Could the thermostat be stuck open?...... Easy to do, especially if I can do it. Cheap to replace too

Don't stroke it, TAP it!!!!.....

[modustollens]

Thanks for the advice. The problem did not recur on the way home. I looked at the temp sensor wire and buffed up the connector - I assume this leads to the dash's temperature gauge?.

But from the manual it looks like the thermostat opens and closes without any electrical signal at all it being a purely temperature sensitive mechanical control. Anyway, I am sure the coolant was not circulating around for the radiator and its hoses were stone cold; so perhaps the thermostat was stuck closed or just still too cold to open? After all, I had only been driving a short time. Though in the past the cab heat would work and the temp gauge would never red line. Maybe if I had drove a bit longer the thermostat would have opened up and started passing hot fluid into the cooling system and the cab heater circuit?

I did add some antifreeze a few days ago; but I have not tested with a hydrometer the freezing point; I am sure I will need add more; but I will need find a hydrometer to make sure I am well situated for the extreme temps.

Thanks again fellows!

MT