I have a 54 plate TDI Octavia that last night on the way home got quite hot but not dangerously. I thought it was the temp sensor so I changed that. This morning it hit 130 climbing a hill should be 90. Have swapped thermostat which was opening but not very far. It’s still overheats. The top radiator hose is hot and the bottom hose is cold. I also have no heat in the cabin from the heater. I think it is either a blocked radiator or a failed water pump. Any suggestions how to try and diagnose which as both are pretty labour intensive to get out.

key issues?

Edited 7 October, 20214 yr by DeanVRS20VT
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Are the temp sensor and thermo genuine items? Our cars are known not to work well or give false warning with aftermarket version.

 

I’d also flush the whole system and rebleed it too.

Dean, I am stuck in rural Devon so only had access to a Hass temp sensor and an unknown make of thermostat. Will try to get some genuine ones.

Dean still doesn't explain the heater not getting hot does it. Can I try it without a thermostat?

Thermostat fitted backwards?

 

Aftermarket thermostat lacking the circulation hole?

 

Heater would work with a blocked radiator, rather too well in fact, what you are describing points to thermostat but you really need a genuine temperature sender to have faith in the readings, if the whole system were at 130°c I would expect to see the pressure cap blowing off steam.

Any suggestions for where to get genuine parts from, Skoda Exeter can only get them for possible Saturday probably Monday and they was £40 for a thermostat and £48 for a temp sensor.

TPS.

TPS wont sell to me as I don't have a trade account, is that normal.

1 hour ago, Bigsurfer said:

TPS wont sell to me as I don't have a trade account, is that normal.

It is, but some still sell to the public. If TPS doesn't sell to you, Skoda will get the same part and send it out to you.

 

Dean thanks for that, I have used a thermostat and temp sensor of a friends octavia genuine parts and known to be working and still the same situation. Pretty sure there is no circulation of water at all so my money is on the waterpump. Just trying to work out if I can be bothered to do the waterpump and timing belt myself, I have done it before or pay the garage but they can't fit me in for 1.5 weeks. I think its was over 1 days work for me from memory. 

43 minutes ago, Bigsurfer said:

Dean thanks for that, I have used a thermostat and temp sensor of a friends octavia genuine parts and known to be working and still the same situation. Pretty sure there is no circulation of water at all so my money is on the waterpump. Just trying to work out if I can be bothered to do the waterpump and timing belt myself, I have done it before or pay the garage but they can't fit me in for 1.5 weeks. I think its was over 1 days work for me from memory. 

Keep us updated mate, all the best.

6 hours ago, Bigsurfer said:

54 plate TDI Octavia that last night on the way home got quite hot but not dangerously. I thought it was the temp sensor so I changed that. This morning it hit 130 climbing a hill should be 90.

I think you already wondered about this, but my first thought was "water pump".

22 hours ago, KenONeill said:

I think you already wondered about this, but my first thought was "water pump".

Likewise water pump. If rad blocked or thermostat not opening the heater would still work presuming not low on coolant or air locked 

 

Edited 8 October, 20214 yr by bigjohn