98 Polo heater problem

Dilbert75

Colleague has a 98 Polo 1.4. About 2 months ago, she & her husband came out one morning and started the car, drove the couple of miles to work and realised that the cabin heater wasn't heating up. They reckoned the engine was reaching operating temperature ok, but given the short journey I'd be surprised if they'd noticed anything out of the ordinary. My first thought was that the head gasket was going / gone.

A couple of weeks later, within 10 mins of leaving Cork Airport, the needle went into the red and they pulled over. Called AA and AA man said that it was very low on water. Topped it up and sent them on their way. Drove the 85 miles home with no problems. No leaks since.

They brought it to a mechanic who said that the problem was a faulty board controlling the heater. Replaced that but made no difference. Changed thermostat but made no difference. Did some sort of dye test on the cooling system and are adamant that there is no gasket problem.

So, after a new thermostat and heater control board, and countless hours of poking and prodding, they still have no heater in the car. Anyone got any ideas?

mike65

Faulty heater valve control? Does ANY warm air get generated?

Any signs of air locks?

Mike.

Squirrel

Was it brought to a Volkswagen mechanic?

BrianD3

Maybe a water pump problem? Well known problem on some VWs, apparently the impeller blades on the pump shear off, the pump spins but there is poor circulation. This could result in cold water in some parts of the cooling system and hot water in other parts.

The low coolant level noticed by the AA guy could have been due to the engine boiling over and losing coolant i.e. the low level may have been a result of the overheating as opposed to being the cause of the overheating.

Dilbert75

No heat being generated at all. I thought the same about the low level being caused by overheating. AA man did have to squeeze the hoses to get the water through. I wondered also about a blockage of gunk somewhere - would it be worth flushing out the cooling system?

Wasn't brought to VW mechanic - local guy would charge WAAAAYYYY too much to make it worth while. Nearly cheaper to scrap it. Or ask about on forums such as this for the benefit of other peoples expertise and experience!!

mike65

No harm in flushing the system, best way is to unclip the bottom rad pipe, then get a hosepipe and simply set to Stun and flush via the resovoiur filler cap until there's nothing but clear water comming out the botttom. Then reconnect pipe and refill system with 50/50 mix of water and anti-freeze.

On a completly different tack, is there any suggestion the heater control on the dash is'nt working properly ie dial turns too easily which might suggest its not connected the the valve. Thats something you could proberly check visually under the dash.

Mike.

ibanez

Flush the entire system and check the pipes that lead to the heater matrix if the pipes get warm and still no heat in the car the matrix could be blocked.