Auxilliary Heater Question.....

[sicknote]

Hi I have a 1.9tdi MK2 Galaxy. I have been having problems with intermittent overheating, heaters blowing hot then cold etc, etc, etc. After several checks I now believe that the Aux Heater and Electric Run On Pump are not working and thus causing problems with air locks. Is it possible to disconnect and blank off the Aux Heater so no coolant runs to that part of the car and then remove the electric pump until I can service/repair all the parts etc.

[chrispb123456]

Firstly the run on pump not working will not stop an engine overheating it's job is to stop heat build up in the cylinder head and aid circulation through the rear compartment heater and correct operation of the booster heater.

 

What you need to do first is confirm the engine water pump is OK because it's a known problem that the impeller can shear off or spin on the shaft, you can physically check this by removing thermostat housing which is where the lower radiator pipe attaches to the block, you can see the impeller through the opening.

 

Also check to see if coolant is being returned to the bottle through the small pipe on top of bottle.

 

Of course there could be a blockage in the system but air entering the system is most likely to be head gasket failure

[sicknote]

Thanks for the reply. I have removed the stat and checked the water pump at the same time, the car is now running without the stat. It overheated last night and when I checked the pipes at the Aux. Heater were all cold (even though the engine was red hot!). I bled the system again and also squeezed all the pipes into and out of the Aux. Heater then left it overnight.

 

I have taken it for a run today and it does seem a little better, it came upto temperature and the heaters are blowing constantly hot but the pressure in the coolant pipes is such that they can't be squeezed and the water level in the expansion tank has dropped to below minimum (when the cap is opened the coolant rushes back to max). I have also cleaned and checked the return pipe and coolant is flowing through that (although it can be quite frothy!).

 

I would assume the froth, pressure and constant air locks (this is the 4th time the system has been bled in 2 weeks) would point towards Head Gasket?

[chrispb123456]

Sorry to say yes head gasket.

[seatkid]

It overheated last night and when I checked the pipes at the Aux. Heater were all cold (even though the engine was red hot!). I bled the system again and also squeezed all the pipes into and out of the Aux. Heater then left it overnight.

 

I hazard a guess that this points to a duff water pump, I'm fairly certain the aux heater would be self bleeding. Heaters blowing hot then cold also seem to support this. The common problem is the impeller in the pump is plastic and becomes detached from the shaft. Even if you stick your fingers in to check if the impeller is loose may not work as you could move the impeller a little and it seems as if its on the shaft firmly.

[Scorpiorefugee]

I've had pump impeller failure on this model and it gave no problem with the heater. It also ran fine in this sort of weather and I drove 200 miles up the A30/M5 and survived by keeping below 55mph (It returned nearly 60mpg) and found that it was OK ticking over in queues and round town so long as the heater was on. The symptom with the water running and frothing in the header tank is to be expected if you take the cap off once it reaches temperature. I should have thought that if you run it with the cap off while still cool you would see bubbling and frothing in there if you rev it and the gasket has gone. However. in my case I whipped it into my favourite garage pretty quickly so Seatkid's comments may be as reliable as usual.

It may well be that in my case the pump for the Auxiliary heater may have kept my engine cool and the heater working so I cannot really see how your symptoms as given allow a definite diagnosis but I hope my experience may help you understand the possibilities a bit better.

One thing is certain and that is you should always insist on the pump being replaced with the cam belt as the life of each seems to be much the same and failure is usually associated with a burst of higher than normal revs such as descending a steep hill in low gear which is what I think set mine off.

[new nige]

I have replaced the glow plug on my aux heater and all is well. However it dose seem to run quite alot of the time even after a 20 mile run, is this normal? Anyone know how much fuel it consumes, it sounds a powerful thing and the lable suggests it pumps out 5kw.

[acecard]

Maximum heat generation is equivalent to 5kw as you say. Maximum fuel consumption is 0.7 litres per hour.

iirc it should cut in when both air temp is below 10deg and engine temp below about 70deg - so when you reach normal engine temp, it should shut down - which you should reach easily with a 20mile run and the eberspracher operating.

I stand to be corrected on the temp figures though.

[new nige]

ta very much cuts out above 10 degrees will have to check the 70 degree shut off but expect its ok

 

ta