TDI heats up slowly

I have recently purchased a 97 Golf Variant TDI (90hp. The temperaure gauge goes up very slowly. Driving to and from work the temperature never goes over 70 C and it is after about a half hour of driving. Outside temperature 0-5 C. If I increase the inside temperature the gauge will go down below 70 C.
I have checked the block temperature and it is the same as on the gauge. The VW customer service tells me its nothing wrong, they claim it is becuse the engine is so efficient. When I had it serviced they checked the termostat and they said it was OK.
I wonder if this is normal or is something wrong?


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Yes, it's normal. Diesel engines are designed to keep a lot of heat in the engine itself, without losing it out the radiator. Diesel fuel burns more efficiently in a hot engine. It makes sense when you think about it: An internal combustion engine is intended to change the chemical energy released by combustion into mechanical energy. Any heat produced by the engine is "wasted" energy. A diesel engine is better at preserving that heat in the engine and using it to increase the efficiency of the combustion. That's why they install a lot of insulating materials all around the engine. There was some discussion in this forum recently about commercial trucks with their radiator grills covered during the winter. Someone asked "why is that necessary when the thermostat will shut off the water flow anyway?" I just had an idea: The radiator cover is not intended to reduce the cooling of the water in the radiator, it's intended to prevent the loss of heat from the air under the hood!

-mickey

I live in Toronto. My A4 Jetta always climed to the 90C mark no matter how cold it was - and we are talking as low as -15C. It did take a while at time to "warm up" sometimes (15 min, part city, part hi-way/motorway), but it always reached the middle of the guage.

The TDI (99 models for sure and I assume earlier ones as well) include 3 additional glow plugs in the coolant to speed warm up. I saw a partial schematic; the ECU can turn on one, or all three (two are in wired in parallel). You may want to check them with a voltmeter when the car is cold. I do not know the temps at which these are "fired up". You can measure them without removing the wire boot. I do know that at -10C they should be both on.

I have a 1999 Golf 90hp. The temperature stays at at steady 87 C or 190 F. Outside temperature at this time of year here in Arkansas is 80-85 F. Since diesels are more fuel efficient. Meaning they use the expansion of gas more efficiently they will run cooler. Totally agree with mickey.

Sounds like it could be the glow plugs. The last days the outdoor temperature has been higher, up to 25C and the engine heats up quicker and reaches up to the 80C mark. Do you or anyone else know where these glow plugs are located?

Johan,
It seems normal to me. Indeed the new TDI produces less heat as normal diesels or TD's. The switch on temp for the glowing plugs are around 0°C. The heatup of the engine with an outside temp between 0-5°C is about 20-30 min. depending the driving conditions. In Europe the luxe versions of the TDI's are equiped with an extra water heater (on diesel) that gives you 3KW of heat with a compumption of 0.4L diesel an hour. The heater is an D3W of espar, special equipment for VW/FORD/SEAT. How they work can be found on www.espar.com From there you can browse to the geman mothercompagny or to the UK site. By the way that heater switches on at 5°C and heats up the car in 10 min when outside temp is not lower than -15°C even at idle.

The earlier Tdi's do not have the extra glow plugs that Jimmy is talking about. I believe that the first car to have that was the new '98 Passat. VW did it because the Tdi can take so damn long to warm up! My 96 Tdi doesn't have the extra glow plugs in the coolant. If I want to warm up quickly in cold weather then I have drive fast!

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1996 Passat Tdi estate (wagon)
1988 Peugeot 305 diesel estate
Visit me at http://www.geocities.com/MotorCity/Garage/5067/

On the 99 (A4) TDi engine, the 3 coolant glow plugs are on the right hand side of the engine, mounted close together (about 1.5cm apart). A black wire connects to each and has a long "boot" (not unlike a spark plug) with a 90 deg turn at the top. They are controlled by two relays and the ECU. I may be wrong, but I think these relays live in the little black box mounted on the firewall, near to the MAF connector (left side of engine compartment). They are actuated by the ECU.

Current for Glow plugs goes thru the two 50A fuses on top of the battery (one closest to 110A fuse perhaps?).

I do not think these glow plugs are monitored like the engine glow plugs. If any one of the four engine glow plugs fail, the ECU it triggers he "Check Engine" light. If you upset the engine glow circuit, the light will need to be reset using the VW VAG1551 tool or similar.

Hello guys !! My name is Pedro and i´m from Portugal. I have an Seat Ibiza TDi (110hp) and i just want you to know what are my numbers in relation with temperature.
With an 5W40 synthetic oil and at a stabilized speed of 100 km/h (60 mph) my car as the temperature of 94°C .
With an 10W60 synthetic oil and at a stabilized speed of 100 km/h (60 mph) my car as the temperature of 98°C .
At idle my car stabilizes the temperature at 90-92°C (i only know with 5w40 oil....)
And in Portugal the temperature normally is between 10-12° in Winter and 30-35°C in Summer, but at that speed my car doers not rise or lower the temperature.....the only thing that i note different is the time that the car takes to rise stabilized at that temperature/speed
Sorry my bad English, but i would like to share my "numbers"
Bye Guys......


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Pedro Jorge