2003 Octavia 1.9 TDi

Since the cold weather struck I have noticed that when the ambient temp. is below 0c the engine temperature gauge needle does not leave the stop for the first three miles which is mostly downhill. It rises and reaches operating temp. after the next 4 miles which are mostly flat It was not like this when the weather was warmer.

I have noticed an increase in fuel consumption of about 6mpg and I use the same route every day.

Local garage think that thermostat needs replacing but cannot tell me how long it should take to warm up when thermostat is good.

My old petrol Felicia was blasting hot air after 2 miles but our diesel Focus takes as long to warm up as the Octavia and a garage said it had a new thermostat fitted.

Is there a standard warm up time when the engine is left to idle?

Is there any way to tell if the thermostat is working properly

you will have an increase in fuel consuption as the car will use more fuel in the cold weather thats answers that one

also with it being so cold it will for sure take a little while longer than normal. how long do you leave the car to idle to warm it up ???

surely if it was the thermostat it would either overheat or temp just wouldnt go up as its always open..?????

Edited 4 January, 201016 yr by westallc

Diesel engines take much longer to warm up than petrols. I tend to keep the car in one higher gear than normal on a morning to quicken getting the car up to temperature e.g 4th rather than 5th. Your down hill stretch then flat wont really be working the engine which is why it is taking its time to get warm. I wouldnt be unduly worried if it was my car.

I agree, all sounds perfectly normal for a 1.9TDi

2003 Octavia 1.9 TDi

Since the cold weather struck I have noticed that when the ambient temp. is below 0c the engine temperature gauge needle does not leave the stop for the first three miles which is mostly downhill. It rises and reaches operating temp. after the next 4 miles which are mostly flat It was not like this when the weather was warmer.

I have noticed an increase in fuel consumption of about 6mpg and I use the same route every day.

Local garage think that thermostat needs replacing but cannot tell me how long it should take to warm up when thermostat is good.

My old petrol Felicia was blasting hot air after 2 miles but our diesel Focus takes as long to warm up as the Octavia and a garage said it had a new thermostat fitted.

Is there a standard warm up time when the engine is left to idle?

Is there any way to tell if the thermostat is working properly

I have a 2008 Octavia 1.9 TDI and in this recent weather it seems to take the temperature guage much longer to come up off zero. Certainly it is not up to operating temp (90 deg C) until five miles or so. If it is switched off and left a few minutes it will cool quickly.

I have read diesels are much "colder" than petrols so this may be normal.

I have had a couple of thermostats fail on me in petrol engines and it seems to me they always fail "open" so the water circulates through the rad much earlier than it should. The result is usually a mixture of the following:

- poor starting

- a cold engine which doesn't heat up,

- a refusal to come off fast tick over i.e. the choke. NB tick over on your car is 900 rpm when hot but it is normal if it is between 800 and 1000 rpm when hot.

- greater fuel consuption.

if it were stuck in the closed position the car would tend to overheat and perhaps boil over once fully warmed up.

The old test was to put the thermostat in water in a saucepan and heat it up on the stove then watch it work.

This isn't posible these days since they are usually burried in sealed units.

Another test is to start the car from cold with the bonnet up. Place your hand on the top radiator hose and wait for a rush of hot water to heat the hose under your hand once the thermostat opens.

In any case I am sure a dicky thermostat will show up on a diagnostic test so I would try a VAG garage first. My 1993 Jeep showed a faulty thermostat by blinking the engine warning light so surely a European car with computers on board would be able to let you know?

Diesel engines take much longer to warm up than petrols. I tend to keep the car in one higher gear than normal on a morning to quicken getting the car up to temperature e.g 4th rather than 5th. Your down hill stretch then flat wont really be working the engine which is why it is taking its time to get warm. I wouldnt be unduly worried if it was my car.

Ditto: plus you'll have your heater on, which hammers the MPG a lot more than aircon :(

My 1.9 TDI's the same in this cold weather, much longer to warm up.

Makes me wonder of one of those plastic bolt on radiator grill covers for the Octavia might be worth trying - anyone ever seen or know someone who's used one?

Yup, mine's the same also in cold weather. In fact in recent weeks mine only reaches around 70°C no matter how far I drive.

The behavior you describe is perfectly normal. My 2.0 Octy PD was about the same a,d my present 2.0 125 kW CR Yeti is even a little slower.

If after a few miles the temperature gauge goes up to the normal 90°C and stays there ion normal driveing, forget it. It is working as prescribed.

Simple test, get the car up to temp and then leave it ticking over in cold weather for 10 to 20 mins, if the thermostat is stuck wide open the temp will come back down

If the thermostat is okay it should maintain the needle in the middle of the gauge

My 2.0 PD TDi is the same, this morning at -4c it took 7 miles before the temp guage got to 90c and then it sat there as it should. The reason for this behaviour is that a diesel engine is more thermally eficient than a petrol, so takes a very long time to reach normal temperature in these cold conditions.

I have noticed an increase in fuel consumption of about 6mpg and I use the same route every day.

You will normally be running winter diesel now which gets less mpg than the summer variety. With the sold snap you guys had you may even have what is often called Alpine diesel which is modified for even colder temperatures than standard winter diesel. It goes without saying that Alpine diesel gets even worse mpg than winter diesel.

Be thankful. If you had standard diesel your fuel would have waxed up and you would have been walking to work. :-)

Diesels are slow to warm up due to their inherent efficiency, and that most of them have a big iron block to warm up (most petrols these days are now alloy blocked).

Yesterday when it was particularly cold, my car eventually got up to 75 degrees after 5 miles or so. I was then stuck in slow moving traffic for another couple of miles and the temperature actually went down to 60 degrees.

I've a long downhill stretch on my commute (both ways). When it was -4°C or so and I was being forced to drive slowly by other traffic, the temperature gauge reading almost dropped to cold. Guess it took 10 miles plus to indicate normal. My Passat diesel tended to do that as well. Heater seems to work OK though.

After reading all the above I've stopped worrying about the thermostat being faulty.

Thank all for saving me the cost and fitting of a new one.

Be thankful. If you had standard diesel your fuel would have waxed up and you would have been walking to work. :-)

I can remember the days of adding Petrol to Diesel in cold weather to reduce waxing, Im not sure how the modern diesel engine with finely tuned injectors, bags of sensors & turbo would cope with that.

I can remember the days of adding Petrol to Diesel in cold weather to reduce waxing, Im not sure how the modern diesel engine with finely tuned injectors, bags of sensors & turbo would cope with that.

You should be adding kerosine not petrol today. I think the ratio is 5 parts diesel to one part kero but you'd need to check that.

I can remember the days of adding Petrol to Diesel in cold weather to reduce waxing, Im not sure how the modern diesel engine with finely tuned injectors, bags of sensors & turbo would cope with that.

You should be adding kerosine not petrol today. I think the ratio is 5 parts diesel to one part kero but you'd need to check that.

Yup, mine's the same also in cold weather. In fact in recent weeks mine only reaches around 70°C no matter how far I drive.

Something doesn't sound right there, because even at -8 degrees my car was up to 90 on the gauge within 5 miles from stone cold.

My 1.9 TDI's the same in this cold weather, much longer to warm up.

Makes me wonder of one of those plastic bolt on radiator grill covers for the Octavia might be worth trying - anyone ever seen or know someone who's used one?

You can use aluminium foil wrapped over the lower or upper part of the grill. This reduces the flow of cold air over the radiator and so means the car is up to operating temperature sooner rather than later. I can remember many years ago on old cars seeing half the grill covered.

The BMW's with efficient dynamics have a set of flaps that open and close the grill to aid the engine warming up.

Edited 6 January, 201016 yr by cheezemonkhai

Yup, mine's the same also in cold weather. In fact in recent weeks mine only reaches around 70°C no matter how far I drive.

Something doesn't sound right there, because even at -8 degrees my car was up to 90 on the gauge within 5 miles from stone cold.

This might be why

http://fmi.fi/weather/local.html?Keywords=&param=4&map=1&place=Jyvaskyla

You should be adding kerosine not petrol today. I think the ratio is 5 parts diesel to one part kero but you'd need to check that.

It used to be a gallon of petrol to a tank of diesel. I can also remember truck drivers lighting fires under the diesel tank, that was pre Health & Safety but it worked

Edited 6 January, 201016 yr by Stuart_J

my felicia 1.9d gets to 80 degrees & stays there, I also have a 1.3 mpi which is the same 80 degrees, after I changed the thermostat ..before it never warmed up & heater was just warm, the diesel does take much longer to get hot.

If a thermostat fails 'shut' engine will boil over, if it fails open it will never get to normal temp in winter. felicia 1.3 thermostats fall off the housing leaving the port open & running cold.

2003 Octavia 1.9 TDi

Is there any way to tell if the thermostat is working properly

IIRC you remove it and put it in a pan of water and heat with a thermometer. IIRC the temperature it's set for is stamped into it. Older cars used to have radiator blinds to block some of the radiator area. With a temperature gauge on the dash it should be possible to blank part of the radiator on cold weather to get optimum warm up time. If the gauge goes over the 'normal' running temperature remove more of the blanking until it's no higher than normal for the whole of your journey.

Edited 21 February, 201016 yr by icarusi@hotmail

Not sure if it might affect it if there is an electric fan then it should only run when exceeding normal temperature. If it is on all the time that that that would probably keep the temperature down below design level.

Not sure if it might affect it if there is an electric fan then it should only run when exceeding normal temperature. If it is on all the time that that that would probably keep the temperature down below design level.

If you have dual zone climate then the fans run all the time whilst the engine is running regardless of coolant temp. The flow of coolant through the raditor is regulated by the thrermostat so it doesnt really matter that the fan is running as until the water is hot then there should be no water actually flowing through the radiator.