CDTI cooling troubles

[vfr16v]

Hi everyone,

Strange problem with my 04 ZT cdti.
Today I noticed that the heater wasn't working (as normal). It took 15 mins to turn warm, although the coolant temp was 90 degrees.
After a while (at HIGH) it blows hot air but only when I was revving, not when idle. And not a constant temperature, sometimes colder and sometimes warmer.
When I arrived at my work I looked into an empty coolant tank. I filled it up and bleed it. It was not immediately fixed but now it seems alright.
When revving I can hear water stream inside the car. I can't find a leak with my naked eye. It's also dry under the car and it run fine
I removed the engine cover but seems dry everywhere!
Suggestions? I badly need the car for my work and next Friday I'm going to Germany.

[T-Cut]

Sounds like air in the cooling system. I'd suggest a couple of things. Fill and bleed the system using the correct method. It's regularly discussed and I'm sure someone will be along with the details.

I would predict that your normal running temperature is too low. So, the second suggestion is to fit the in-line thermostat modification. Again, a simple search will pull out lots of information. You need to get the running temperture near 90C if possible. You can only find out what temperature it's now running at by usingthe trip screen diagnostic made (Test 7): http://www.the75andztclub.co.uk/forum/showthread.php?t=55585

TC

[SD1too]

Peter,

The correct filling and bleeding method for the diesel is here (http://www.the75andztclub.co.uk/forum/showpost.php?p=1558211&postcount=12).

Simon

[vfr16v]

T-cut, there's a new thermostat fitted last year. Running temperature is around 90 degrees. Never had troubles after the original was replaced last year. Now it's out of coolant. Looks that there's a leak somewhere

@ Simon, thanks :)

[T-Cut]

T-cut, there's a new thermostat fitted last year. Running temperature is around 90 degrees.

OK good. The fill'n'bleed ought to fix it temporarily. The cause of the coolant loss needs investigating. The pump/thermostat area is typical in diesels, but it could be anywhere there's a join/joint.

TC

[ChestersDad]

1. Further to the above - may be worth trying a vacuum fill (diy or local garage) where the air is evacuated and the coolant mix is drawn in.
This will tell you if you have a leek as you won't achieve a vacuum if there is a leak or it will be lost quickly and secondly is it a really good way of getting coolant to those awkward air trap places - I know I've got an old Land Rover!!! :eek:

2. Assuming the obvious has been checked (pressure cap, seals, gaskets and hose clips and drips) in respect of finding a leak I have had great success with a hand sprayer bottle with water and a drop of washing up liquid spraying over the whole system route.
In the past I found a very small crack in a weld of an outlet pipe on a very expensive ally radiator this way. Loads of pretty bubbles when under pressure.
Got an exchange rad and hey presto hot heater and no more coolant loss! :duh:

HTH,

Good luck!