Quote:
Originally Posted by volvomadwoman
water escapes through the header/expansion tank when it pressurises tto much but on short journeys it doesnt leak out,so looking for another 940 auto estate
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I’m not a mechanic. I’ve never owned an auto. I know nothing about Dave’s fear that water may be leaking into the auto box via the cooler.
BUT:
Do I understand this correctly? Water is escaping through the header/expansion tank.
Do you actually mean the expansion tank?
Does it fill up completely with coolant then eject it through the breather pipe? You state that no escaped coolant can be seen so I suspect not so does the expansion tank now appear empty?
Did you confirm that the heater valve is on the engine side of the bulkhead?
Is the heater valve open or closed? If it’s open then coolant will be able to flow through the heater and leak away. Even if it’s closed I suggest that, as there is a leak in the heater matrix the pressurised coolant is able to enter the matrix via the return end and leak away.
I do not understand how the system is pressurising so much if the heater matrix is leaking, surely that will be preventing a build up of pressure.
I’m still thinking, access those heater hoses and isolate that heater matrix. You will ascertain the state of the heater hoses whilst doing so. Then see what happens.
If the pressure is still building then move on to a suspect head gasket and the usual checks for that.
The “how to change a heater matrix” seems very comprehensive. I agree that it appears to be a long tedious job and would consume a lot of labour hours if someone else needs to be paid to do the work, but, it’s probably still less than the cost of a replacement car, and GreenBrick has a re-cored matrix available, if it is the correct one.
Just to add to the sorry story, I once owned a Ford Cortina Mk3, 1600cc. It was fine around town and on short trips but after a couple of hours on a motorway the coolant all disappeared. The cylinder head gasket was suspect but when the head was removed it was found to be cracked. It was replaced with a good used one. The coolant still continued to disappear. The piston rings eventually gave up (blue smoke etc) so the engine was completely stripped and the block and head checked by a reputable engineering works. No faults were found. The engine was rebuilt but continued to use coolant. No idea where it was going or how. Traded the car into a dealership who wanted the registration number and the Rostyle wheels.
Sorry if I’m on the wrong track here, just trying to help.