Hi all,
I've created a new post for 02 1.9 2002 Passat 1.9 TDI 130 BHP - White(ish) Smthis on going problem as at the time of the other post I had multiple issues on the car - I think it confused the issue. However all of those problems are now resolved, the car is running okay except for one problem. Smoke.
The only problem remaining with the car is that when started after being stationary for over 4 hours a large amount of smoke is produced from the exhust. The amount of smoke does not appear to vary greatly - ie its the same amount of smoke after being stationary for one day as if I left it for 3 days.
The first problem is I can't decide what the smoke is, whether its oil / coolant / diesel etc. It appears a blueish / white and I think it smells of diesel (although the garage say oil !)
Heres a vid clip of the smoke
www.youtube.com/watch?v=RBgCa__sQoc
So far the car has had the following work done to rectify other problems / attempt to fix this problem:
replaced injector on cyl 2
replaced injector wiring loom
replaced wastegate (N75)
replaced turbo vacuum hoses (there was a leak on a small tube)
replaced all glow plugs
changed fuel filter / air filter / pollen filter.
Compression test shows correct values.
I also done an oil change with an engine flush product used, followed by oil filter change.
One test that was conducted by hte garage was they removed the oil cap, when I placed my hand over the hole I could feel hot air coming out in waves with some pressure - the garage tell me that this is a breathing problem but didn't elaborate.
After speaking with various people and the garage they put it down to one of three things:
1. Its running too rich on a cold startup and pumping out unburnt diesel as smoke.
2. Oil is leaking across the steam vavles and building up whilst the car is stationary.
3. Coolant is leaking into the exhust whilst its under pressure and stationary.
I am unsure how to proceed to test each of the above ideas. I was wondering if the following would work / be safe ?
1. Light a match in the exhust fumes and see if it burns / goes bang indicating unburnt diesel??
2. I've added an oil supplement for stopping smoke (it was a very thick gel / liquid substance) they claim it repairs rubber seals and stops stem / valve leaks. - Its made no difference.
3. If I removed the coolant tank cap so the pressure is removed and left the car stationary - would that prevent the coolant leaking into the exhust?
Anyone else have any thoughts / ideas why the car would smoke like it does? Or any other tests that I can do? I have vag-com if you need any readings....
thanks everyone.
Richard
Edited by Pugugly on 27/10/2008 at 18:42
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Richard, Is your car fitted with an auto box?
The EGR fitted to the auto versions of the PD are water cooled and very prone to coolant ingress through micro-cracks in the EGR jacket. It might be possible to bypass temporarily the coolant circuit for the EGR with a piece of hose, for test purposes.
Strangely, the manual cars don't have a cooled EGR.
659.
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hi, nice idea but its a manuel. sorry.
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OK - off the list then.
Any diesel will give a lot of blow-by if you remove the dipstick or oil cap. You're also likely to get covered in black oil. I have never seen one of these engines, reasonably treated, with cylinder bore wear - the valve cam lobes go first.
A diagnosis is difficult without seeing the vehicle, but one more thought:
A very small quantity of brake fluid will produce lots of smoke. You may not even notice the level dropping beyond that caused by normal pad wear. The tandem vac pump exhausts to the crankcase on this engine so any fluid will end up being burnt via the breather.
To check for an internal servo leak, you could try disconnecting and plugging the vac line to the servo prior to a cold start-up test (don't drive it like this). Make sure you leave the narrow vac line to the vac reservoir via the NRV connected to the tandem pump, otherwise there will be "operating consequences" and possibly an EML.
Brake servo problems are not unknown on the B5 if the plenum drains get blocked with leaf mould and the housing rusts through.
659.
Edited by 659FBE on 27/10/2008 at 20:53
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Hi all, think we're getting somewhere, not sure where but here's what happened tonight.....
Firstly its freezing cold tonight, temp is just above 0 degree's C. I went out and started the car - as usual lots of smoke and the sickening sweet smell, lasted for a good 30 secs whilst the car was running lumpy. After that it was fine as normal.
As a test I left it running for half an hour and then switched it off. I went back to the car after it had been standing still in the cold for 2 hours. I hooked vag com up and checked the coolant temp and fuel temp. After 2 hours in the freezing cold it showed 27.8 C for the fuel and 49 C for the coolant temp. Considering it was less than 1 C outside I thought these might be a bit high.
Now normally it takes a good 4 - 6 hours before I get the smoke reappearing on startup - however this time it smoked as thou it was the first start of the day. Again it ws gone after 30 secs or so.
I'm guessing that the temp sensor is reporting a false temp to the ecu / glowplugs - which in turns mean they are not heating up for long enough / at all so a large amount of excess unburnt diesel is thrown out the back.
Does that sound plausible / possible?? I was wondering if I disconnected the coolant temp sensor would that report back as 0 and bring the glowplugs up to max ? Can I start the engine with the sensor disconnected or would it cause all sort of problems?
thanks everyone
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Richard
When you stuck your hand on the engine; did it feel warm? 49 o C is 10 o above blood heat.
The fuel temp sensor is near the engine too.
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soorry didn't think of that. I'm going to leave overnight and run the test again in the morning. I'll post back the results.
cheers
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If the temperature transducer in the block is faulty you will lose the post-heat (glowplugs on after engine started). This will certainly cause white smoke.
Check this very carefully - VAG temperature transducers are bead thermistors potted in epoxy and (of course) fail with thermal cycling. A soft encapsulant with an appropriately designed expansion void and stress relief for the leads would have avoided this.
659.
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>>potted in epoxy and (of course) fail with thermal cycling. A soft encapsulant with an appropriately designed expansion void and stress relief for the leads would have avoided this.
I'm currently learning exactly this lesson with one of my designs - it's too late for drastic design changes, hopefully a change in the grade of epoxy will get me off the hook!
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You might well have a job on your hands - I hate the stuff. It has a very high linear coefficient of expansion and will rip electronic components and soldered joints apart. It's essential in any design to avoid what I call the toothpaste effect. This is where a large bulk of material has a smallish cross sectional area for expansion and thus gives rise to a high degree of linear movement. This will rip anything apart - as it does with the VAG thermistor potted into a brass sleeve with a space at only one end.
If the design is wrong, changing the grade of epoxy won't help. Configuration and stress relief provision are far more important than material choice. Polyurethane rubber is softer and has a slightly lower expansion rate, but you still need the right design.
I used to test engine mounted components for 500 cycles - ambient to max working. There was then an all-important microscopic examination for fatigue. It's no good testing the thing functionally as the joints may be hanging on by a thread. I wish more designers had a proper understanding of this - it's a remarkably common failure mode (speed probes do this all the time).
659.
Edited by 659FBE on 29/10/2008 at 12:22
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Coolant temp sesnor was a red herring I think. I left the car overnight and went out this morning. Coolant temp / Fuel Temp / Air temp all read within 1 C of the outside temp (4.5 C) Guess it takes longer than 2 hours for the coolant to cool down.
I decided to change the pre glow period anyway - I bumped it up to 7 secs via vagcom and started the car. Made no difference - still lots of smoke and the smell.
Could it still be the afterglow? or would you now suggest the air/fuel mix. Is there a way of looking at the amount of air and fuel the car is starting up with?
thanks
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>>Polyurethane rubber is softer and has a slightly lower expansion rate
Yes, this is where I'm pinning most of my hopes - some trials are running at the moment. We are limited in material choice by fairly stringent outgassing requirements.
Thankfully, there's no "toothpaste effect" at work.
We have micro-sectioned our solder joints after thermal cycling to prove our soldering processes, but, in this particular case, the failure was much more stark, with cracks forming in the epoxy itself.
It's one of those times where I wish that someone else's initials were on those drawings! A more positive way of looking at it is that it's when things don't quite go to plan that you learn something.
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Richard,
I know your post is quite old now but I have a 2001 passat 130 that seems to be showing the exact same symptoms as your car, the white (ish) smoke only appears when the car is cold or when it has been left to idle for more than about 15 - 20 mins. did you ever get to the bottom of the problem? My car has been in and out of an independent garage for the past 4000 miles but they still haven't gotten to the bottom of the problem, an additive has been added to the engine old but this made no difference. the mechanic is now suggesting that the engine is worn and needs replacing!! as you can imagine I am slightly reluctant to do this as the car has only done 110,000 miles which I believe is not much for this engine.
Any thoughts or comments gratefully received.
Thanks,
Donald
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