Hi everyone,

I have searched and searched for answers to my heater problems and still cannot find any definite solution!!!

Symptoms:

Heater blows cold at low speed
Heater blows warm (not hot) only above 2000 rpm. Slightly warmer to the passengers side.

Things I have checked/tried:

Check temp flap motor works.... I assume this is one of the three motors on the side of the heater box that you can get to when the glove box is removed (I don't know which one is the heat flap). All three motors seem to work anyway.

Check heater hoses.... Inlet is hot, outlet is warm.
Tried to bleed heater core..... Found very little flow out. Problem solved you say!! Its a blocked core!!!
Flushed core with hose.... No sign of debris and very good flow at any pressure. (Damn)
Tried to bleed hose again... Same amount of flow.... No joy.

When bleeding the heater core there is a little increased flow at high rpm and it gives a little squirt of coolant when I back off the accelerator but its still not as much as I would expect. There is very little flow at idle (you can disconnect the hose completely without making too much of a mess). To me it seems that there is a problem with the pressure or the volume of coolant getting to the core rather than a core problem.

I have read a number of posts surrounding auxiliary water pumps (run out pumps) and this looked at first to answer all my questions. I cannot however find any information to suggest that the 2.5 TDi engine has one of these pumps. Can anyone confirm this??

Someone had posted that they attached an aftermarket electric pump and this did the trick.... Not ideal.

Are there other hoses or valves that can get clogged or fail? Does anyone have a diagram or info on the TDi rather than 2.7T??

I know there has been much talk around this subject but other than a blocked core or air lock there doesn't seem to be any other confirmed solutions to this problem.

Any help would be much appreciated!!!

 

Is the thermostat ok? its very common to fail on the 2.5, what temp does it sit at?

when bleeding I assume you are bleeding it from the upper hose pulling it back a little until the small pin hole is shown and water should flow out after a while, it should be a constant squirt of water though,

regards

Andy

 

Hi Andy,

Vehicle temp gets up within a couple of minutes of running and stays at half. I am pretty sure the thermostat is working as it should.

Yes, I have been bleeding the system through the small hole on the output pipe of the heater core. There is never a constant flow from this hole however, just a squirt when you come off the throttle.


I am still scratching my head over this one!! I think the next step is to maybe try an accessory pump to see if I can increase the flow and pressure into the core. Somewhere I read another post where this had done the job. This idea wont really fix the initial problem though so is not the best solution.....