Hi all, have a 2005 octavia 1.9 TDI,owned for just over 3 years and just up over 200,000 miles but drives great but has recently started getting hot on a run,always previously sat bang on 90 degrees but will now more often than not go up to three quarters on the temp gauge and when I switch off the fan keeps running for quite a while,not losing any coolant at all......could this just be a thermostat fault and if so are these an easy change......thanks

Could also be the water pump not pushing the coolant around fast enough.

Never thought of that.......thanks.water pump and timing belt changed 3 years ago but anything can happen

Check the condition of the radiator.

The visible part at the front is the AC condenser, use judgement to assess whether it could indicate condition of engine cooling radiator behind it.

I have a 2006 1.9 and improved AC performance and engine cooling by carefully cleaning the matrix with a pressure washer.

It's amazing the amount of crap that clogs it up.

Yes, as above check the rad fins and air con fins and matrix as the radiator, being behind the air con condenser matrix, relies on sufficient air flow through the condenser unit in front.  Thermostat is also a likely culprit, if the matrix looks clean enough, I'd probably go there.

 

Then the water pump (but note you have replaced 3 years ago so less likely)  beyond that, some sort of flow blockage perhaps internally inside the radiator itself...   

The thermostat is the easiest and cheapest thing to check. all you need is a bowl of hot water but I would just change it for a GENUINE one if I was going to the trouble of removing it.

...could this just be a thermostat fault and if so are these an easy change......thanks

Does this help at all? Looks pretty straight forward.

 

http://workshop-manuals.com/skoda/octavia-mk2/drive_unit/1.9/77_kw_tdi_pd_engine/engine_cooling/removing_and_installing_parts_of_the_cooling_system/removing_and_installing_coolant_regulator_(superb_ii_octavia_ii)/

Does this help at all? Looks pretty straight forward.

 

http://workshop-manuals.com/skoda/octavia-mk2/drive_unit/1.9/77_kw_tdi_pd_engine/engine_cooling/removing_and_installing_parts_of_the_cooling_system/removing_and_installing_coolant_regulator_(superb_ii_octavia_ii)/

 

It is pretty straight forward the problem is the access is not so good. I have done a few on these engines and have removed the alternator every time just to make it a bit easier.

Thanks all for taking the time for your answers......I can't do much til the weekend now but will keep you informed of what I find.....might be of use to others .

When was the coolant last changed?

Do your fans work and both high and low speed?

Edited 6 September, 20169 yr by Mikek3111

Coolant was changed last year,changed the expansion tank as that was leaking and drained and refilled then.

Fan speeds, I have no idea,I thought it just kicked in when reaching temperature,something else to check this weekend.

My 2006 Tdi 4x4 estate has blown out coolant, replaced expansion tank then kept overheating under load (cools down quickly just by backing off) but now replaced thermostat & sensor & now radiator (lots of sludge out of it!) & still the dash is saying it's overheating & the warning light kicks in - mechanic is getting as frustrated as I am!! Could this be a problem that needs sorting out with a computer check? Any help appreciated, thanks

Top 2 things for me would be either thermostat or a partially blocked rad. Had an old car that ran round just below the red due to a blocked rad. Was a good excuse to run it "swiftly" to keep the airflow up through the working part

Ha 'swiftly'! Thanks, suspecting it might be blocked elsewhere, no heat from the heater at all!!

My 2006 Tdi 4x4 estate has blown out coolant, replaced expansion tank then kept overheating under load (cools down quickly just by backing off) but now replaced thermostat & sensor & now radiator (lots of sludge out of it!) & still the dash is saying it's overheating & the warning light kicks in - mechanic is getting as frustrated as I am!! Could this be a problem that needs sorting out with a computer check? Any help appreciated, thanks

When the radiator was replaced, was the block flushed?

You have to wonder about the water pump in these cases - e.g. the impeller may have detatched from the shaft, so there is no, or very limited, coolant flow.

Iv seen water pumps with the plastic impeller spin in shaft so it dont spin at full speed

No heat from heater says to me either blockage or pump failure. Best get the water pump checked out as that's not a good thing to have broken with the car in use!

Water pump being replaced today, thanks for all your input, much appreciated

Luckily mine was just the thermostat....27 quid for a genuine one but the one that came out was probably the original so can't complain.....happy boy again now.

Good to hear the outcome is a happy one and one of the cheaper options.