craig1410
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| posted on 19/1/13 at 02:02 PM |
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SEAT Altea 1.6 petrol - int. white smoke on cold start
Hi guys,
My wife's Altea (2005 1.6 petrol, 75k miles, owned from new) sometimes struggles to fire up when cold and runs roughly and emits white smoke
(tinge of blue perhaps) for a short time before reverting to normal (good) running. My thoughts are that it is over-fuelling on these occasions either
due to a sticking injector or some sort of cold start enrichment going wrong. I've heard people suggest changing the coolant temp sensor too.
However, 90%+ of the time it is fine so it is either an electrical (wiring/sensor etc) intermittent failure or something mechanical sticking (eg.
injector) in my opinion. Before I start to replace bits or do any further diagnosis I thought I'd ask if anyone has seen this before with any VW
group cars with the same SOHC 1.6 petrol engine?
Another problem I have is that the car is losing a bit of coolant but I don't know if it is a leak or cylinder head gasket starting to go. The
engine undertray tends to hide any leaks and can store water from previous wet days and then make you think there is a leak when there isn't.
I'll probably remove the tray to help diagnose any possible leaks. I do get quite a bit of oil mayo under the oil refill cap but I think this
car has always had a bit of that. No sign of water or emulsion on the dipstick so far.
Any advice on either issue much appreciated.
Thanks,
Craig.
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Slimy38
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| posted on 19/1/13 at 02:32 PM |
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White smoke + coolant loss + mayo does suggest failing head gasket. However, it could also be to do with short journeys and the current cold weather.
Might be worth checking all pipes and joints for telltale coolant signs, with VAG cars using bright pink or purple coolant it tends to be fairly easy
to see.
The coolant temperature sensor and the thermostat are both common failures on VW engines. What does the temperature gauge do when you're
driving? Does it stay solid at 90, or is it going up and down depending on the driving conditions?
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britishtrident
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| posted on 19/1/13 at 04:02 PM |
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As a rule cold starting problems are often to down to the coolant temperature sensor, on modern cars the temperature gauge doesn’t really show
temperature it simply shows what the ECU wants you to see it shows N between 75c and about 115c. To see what temperature the sensor is
actually really reading you would need to use an OBD II or VW diagnostic scanner/dongle that reads live data. OBD II and VW specific
diagnostic tools that read live data aren't expensive (ie dirt cheap on ebay) so it would be worth the investment.
Blueish white smoke on start up traditionally suggests leaking valve stem oil seals but if your are losing coolant it has to be going somewhere ,
however don't assume it is a head gasket a leaking radiator spraying coolant on to the exhaust manifold as the coolant warms up and
expands. will give clouds of blue white smoke and a very distinctive sweet aroma.
Mayo in the top end of the engine can indicate a head gasket problem but more usually it is due to the engine not getting up to working
temperature (80c+) due to a thermostat problem or only being used for short cold weather journeys.
To detect head gasket failure most garages stick the exhaust emission tester probe into the top of the coolant header tank to check for the presence
of combustion gases.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Slimy38
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| posted on 19/1/13 at 04:31 PM |
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If the car has climate control, you can use that to get at the ECU's view of the temperature;
http://www.seatcupra.net/forums/showpost.php?p=1302617&postcount=24
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craig1410
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| posted on 19/1/13 at 06:24 PM |
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Hi guys,
Thank for the comments.
I don't drive the car very often so I'll need to try to get my wife to observe some of the things you have suggested such as coolant gauge
readings but I'm pretty sure she would have noticed if the gauge was giving strange readings. The coolant loss itself was 400ml in something
close to 1 year so not massive. Mayo around the filler isn't any worse than other vehicles I've owned either and since the car does do
regular 4-5 mile journeys, it could be the short journeys that are making it a bit worse, especially in current cold snap. The smoke is mainly white
and quite dense and hangs in the air for a while. It also smells strongly of petrol so I'm leaning more towards fuelling issues rather than oil
usage. The bluish tinge could just be caused by petrol washing the oil from the bores and possibly from the catalyst.
I do have an OBD-II cable and software package for my iPhone (Dash Command) - this shows coolant temperature and allows me to check for fault codes
and reset them etc. There are no fault codes (actual or pending) showing and the coolant temperature seems to be reading correctly. I ran the engine
for 5 mins while watching the value and it rose from 48C to 64C while the dashboard gauge rose from around 50C to almost 80C. The dash seemed to be
reading high but they may be sensing from different places or the dash gauge might be compensating for lag or something. The important thing is that I
was getting a reading which was changing as the car warmed up. Still worth changing the temp sensor though given the low cost in doing so.
So, first action is to just replace the coolant sensor and run a dose of injector cleaner through it. I'll get my wife to monitor it for a few
days and maybe try using it myself a few times.
Thanks again,
Craig.
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ss1turbo
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| posted on 1/2/13 at 03:22 PM |
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As has been mentioned, the dash gauge is only a placebo gauge; the engine is pretty much classed as "warm" when it hits about 65 degrees
(which is when the closed loop running kicks in, from what I remember). At which point the dash gauge would probably ramp nicely to the indicated
90.
When fully warmed up, you'll probably see the real temperature floating between 90 and 100 degrees (or even slightly higher), yet the dash gauge
will stay planted at 90..
Long live RWD...
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