slow warm up TDI

[shaudy]

Hi, I've recently bought a 140 TDI and noticed its takes a lot longer to warm up than the 2.0 petrol I had before. From reading online it seems normal to take a bit longer, but I’ve noticed once or twice the temperature dropping when the car is ticking over which I’ve never seen before on any car I’ve had.

Tonight I drove it about 10 miles and stopped when the temperature was a touch over 85C, then left the car to tick over and watched the temp drop to 75C, which took less than 10 minutes.. I’ve had the car in to VW and they couldn’t find anything wrong. Could that be a sticking thermostat?

Cheers
Shaun

[RW1]

TDi owners will no doubt help on the diesel side ......

Had the temperature dropping back at idle at 85'C on my 1.4.TSi and it was the thermostat (waxstat faulty). It had failed and was holding the thermostat valve open slightly when warming up. New waxstat sorted it. Recently noticed it has started again about 5 weeks ago and the engine in both cases runs cooler on the oil temperature readings at working temperature levels.

Warm-up time was also taking longer.

What you could do is a quick check when the engine is fully warmed up. Stop the Scirocco and with the engine still running, pop the bonnet and feel the top and bottom radiator hoses. (Careful they can be hot!.) There should be a pronouced difference in temperature.

In the first occurrance above I had both hoses at the same temperature. Post new waxstat in the thermostat assembly, I had hot and cold. Need to re-check mine given it seems to have lapsed.

BTW VW(UK) technical stated the car was perfectly normal in its faulty condition the first time round. I ended up buying the part (£25) and only when I was about to instruct the dealer's service department to do it, with the intention of directly claiming off VW did they offer to do it FoC. VW(UK) never paid the warranty, the dealer took the cost.

C.

[samdub]

I found this the other day when it was particularly cold. Try leaving the heater controls off for the first 5 minutes or so. As soon as I realised they were in full heat position on the dials I turned them down and up shot the water temperature to normal. Try using the oil temp page of the MFD to see when she's properly warmed up. Nothing technical here just experience. Hope this helps.

[GeoffT]

Hi, I've recently bought a 140 TDI and noticed its takes a lot longer to warm up than the 2.0 petrol I had before. From reading online it seems normal to take a bit longer, but I’ve noticed once or twice the temperature dropping when the car is ticking over which I’ve never seen before on any car I’ve had.

Tonight I drove it about 10 miles and stopped when the temperature was a touch over 85C, then left the car to tick over and watched the temp drop to 75C, which took less than 10 minutes.. I’ve had the car in to VW and they couldn’t find anything wrong. Could that be a sticking thermostat?

Cheers
Shaun

Not sure if you have a problem but Diesel engines all warm up slower than Petrol ones because they are more efficient and create less waste energy as heat.

[maisbitt]

You'll notice a big difference in warm up times on a TDI in the colder weather. TDI's have a higher internal combustion temperature. Flashpoint of petrol is about 40C, the compression in a diesel engine helps create the temp needed to combust diesel. As diesel has a much higher combustion temp, it takes longer to heat the engine.

In the winter, when the ambient temp drops, and you're more likely to divert engine heat by having warm air blow into the car, you'll see the time taken to get up to normal operating temp increase significantly.

2 weeks ago, my 140TDI was up to temp about 3 miles into my journey, now it's more like 5 miles.

If you have the car ticking over and the blowers are on full for temp, you could be pulling out heat from the engine bay quicker than the idling engine is creating it.

[shaudy]

Thanks for the replies.. I've tried it out with the heater off and it warms up a lot quicker, i guess it's just me getting used to a diesel and I've never seen a temp drop before. The temp drops seem to only happen with the heater on, outside temps lower than 5C and the car not fully warmed up. Once the water and oil are fully warmed I can't really get the temp to drop at all...

I havent had a feel of the rad pipes but will give it a try at the weekend.

Glad this one has heated seats!