White Smoke on Start up and Losing Coolant, are they Linked?

[Shortie1979]

Hi all, after a bit of wisdom! My Audi 04 plate 2.0tdi Sport, kicks out white smoke when started from Cold. This only lasts about 20-30 seconds (about the time it takes me to drive down my lane), if i put my footdown in this early point i get lots of white smoke, but by the time i hit the main road its all pretty much gone! It also can sometimes not start that great from cold (i.e takes a couple of seconds to kick in once i turn the key after the glow plug light has gone out, for reference glow plugs have been replaced pretty recently) Now i know white smoke indicates burning Diesel or it could be steam, which brings me to my other point. It seems to be losing coolant on a regular basis, not a lot but about every 2 weeks the coolant light will come on and i top it up. There are no signs of any water leaking under the car (although this is hard to tell at this time of year) and no signs that it is getting into the head at all (no milky residue on the oil filler cap). Could these 2 be related?? If it could be coolant getting into the exhaust system, where the hell do i need to look to find out?!?! Or is it likely to be fuel? In that case what would you suggest looking at?? Thanks in advance.

[cliffcoggin]

The white smoke may or may not be related to the water loss, so I suggest the leak should be sorted out before worrying about the smoke. The water can only escape from the coolant system via:

[1] an external leak from the radiator/hoses/pump/thermostat/pump etc. You should be able to see a wet spot or dried crud around the leak. Alternatively a  pressure test of the cooling system will confirm.

[2] an internal leak to the engine if the head gasket is damaged. A compression test of the engine will confirm. (A compression test may also reveal other causes for white smoke such as worn bores and valves. Are you using a lot of oil?)

Both tests can be done by a competent home mechanic if you are prepared to buy the equipment, or you take the car to someone who is.

[Magnet]

Hello Wayne,

I would agree with Cliff, and it's quite possible that the two symptoms are not connected. Re white smoke and not staring as well as it should ( smell of diesel as well?) could well be problems with one or more injectors, and this can be checked via. a leak-back test. If it were mine, I would be getting this done st a local and trusted diesel specialist.

Again, I'm with Cliff on the water loss logic, and getting a system pressure test would be the best starting point. Re. compression test, you would need to be aware that diesels run on high compression pressures compared with petrol engines. If there is a head gasket issue between a cylinder and a coolant channel, it will not necessarily show up on this test since the relative compression pressure loss may be too small to assess.

Kind regards,

Gareth.

[Shortie1979]

Cheers guys, i will get it looked into

[Dan3222]

Does your engine have an EGR cooler?  I have known of vehicles with a break in the welds allowing water to very very slowly leak into the exhausts system, causing a white smoke which takes a wee while to dissipate. Once the engine warms up, say 4-5 mins, the exhaust gasses are usually hot enough to fully evaporate any water in the system hence clearing the white smoke effect. 

Irronically enough, I had a 2.0 TDI on a 58 plate that I had to top up the coolant every 3-4 weeks, this was from new too. Audi said it was to slow a leak to diagnose the source and even blamed my driving style..... creaky bugg-ers. But saying that they could fix any problem, I did 125k in that car with no other issues except a new turbo at 65k.

good luck

[Shortie1979]

Hi Dan, I dont believe my one has an EGR cooler as its the old 2.0tdi (not the common rail one you would have had)

[elikalac]

Hello, sir. did you find the cause of the leak and white smoke?