fuming through dipstick questions

Hello,
i'm looking after a used passat in a dealership and after several visits i got them to agree to allow me to take it to a mechanic, so we take it and the first thing my mech does is take out the dipstick, then the engine starts fuming through the hole(pulsating smoke, kind of like a mini steam locomotive at the idle rythm) so my mech told me "i wouldn't touch this car with a 10-foot pole, this is at least broken rings and you'll be looking at a full engine rebuild which will take you back 4~ grand or more".
It was still fuming even after putting the dipstick on through the sides

Then later that day the dealer calls me that he took the car to another mechanic shop and they checked the car and said it was in mint condition, that the fuming was normal for a passat tdi and that the turbo was also ok.

Now of course i'm torn, the first mechanic i took it is a trusted guy i know and i'm sure he wouldn't be bull****ting me.

So, ¿is this -in fact- normal or i should be walking quietly away from that deal?(which was sweet in the first place, maybe *too* sweet )
Maybe it's a broken CCV?, i saw no MILs or warning lights on the dashboard or the central MFD display...

The car is a 2006 Passat TDI(2.0 engine, 140BHP) DSG with 75000km(if i where to believe the odometer reading ).

BTW, when i first started it in the dealership with the hood off, it was quite noisy and vibrated a lot, but after reading the FAQs here it seems that's not abnormal.

thanks for any info guys!

Being a turbocharged compression ignition engine, the blowby will be much higher than on a naturally aspirated spark ignition engine. It is a combination of compression ring design/arrangement and high cylinder pressure.

If you remove the oil fill cap while the engine is running, the engine will blow it away if you don't hold on to it.

I'm not sure what you meant by "it was still fuming after putting the dipstick on through the sides."

Traces of oil in the intake pressure pipes is also normal, and not a cause for concern.

The DSG must be serviced every 40000 miles (65000 km) for best service. It's expensive, but you can save some money doing it yourself with wholesale/discount genuine factory parts (or OEM equivalents).

Thanks jcrews for your prompt response, i knew i came to the right place, so far i only drove an 2.0 HDi engine(PSA group) that's smooth as silk and has zero blowby even after 250000km.

i didn't knew crankcase pressure was so high on this VW TDi engines, by still fuming, i meant that with the dipstick "plugged in" you could still see smoke coming out the sides of it(probably not a perfect seal of the dipstick).

i wonder if there's any youtube videos of a tdi fuming...

There shouldn't be enough pressure to do that. I've never seen it myself. Although there's a lot of volume, the CCV keeps the pressure under control.

The PSA units may have a different vent valve and/or pipe design that reduces the pressure further than on VAG units. I haven't seen one in a while, so I won't take any further guesses

One item you should check when looking at a pumpjet VAG engine is the camshaft on 8V engines. I didn't look to see if that unit is a 16V twin cam unit. I expect (but don't know) those to have better cam wear than the 8V arrangements.

kind of impossible to check the crankcase, i highly doubt he'll allow a partial engine takedown like that

well, it was fuming like a small locomotive whilst idling, like "puf puf puf puf puf puf" of smoke, ofc it wasn't billowing like a smoke machine!, but was very noticeable

Well, i'm a little less torn now, soi can assume it's in fact normal for the engine to puf puf smoke through the dipstick....

I've yet to see the first Internal Combustion engine (gasoline, kerosene, diesel, natural gas, propane, etc.) that had zero blow-by........they do not exist! It has nothing to do with ring design, type of oil, who made the engine, etc. It is just a fact of function. EPA would re-write the rules, if someone come up with an internal combustion engine with zero blow-by (crankcase fumes).

The Intake sytem pulls the fumes from the CCV system located on top of the valve cover. The Dip Stick hole goes directly into the bottom of the engine. It would/could serve as a vent if left open. So, seeing blow-by smoke come out of the dip stick hole is not out of the ordinary..........however, I'd venture to say a cold engine (not warmed up to full operating temp) will have a more blow-by. Therefore, depending on how far away the mechanic friend was located (the drive) the engine may not have been completely warmed up, thus a little more blow-by smoke than usual showed when he pulled the dip stick!.........just guessing!

Eliminateur said:

kind of impossible to check the crankcase, i highly doubt he'll allow a partial engine takedown like that

well, it was fuming like a small locomotive whilst idling, like "puf puf puf puf puf puf" of smoke, ofc it wasn't billowing like a smoke machine!, but was very noticeable

Well, i'm a little less torn now, soi can assume it's in fact normal for the engine to puf puf smoke through the dipstick....

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Well, gees, I didn't realize he pulled the dip stick out while the engine was idling............ totally explains why it was puffing! At idle the Intake "suction" is so low that CCV system fumes will accumulate faster than they will be drawn out....

Also, the fumes from a diesel engine are quite different than those that come out of a gasoline engine, I might add.

I'd say my engine would do the same thing........

I had a volvo 760 turbo (gas) that did that. (that car's name was "Loki" - I now refrain from naming my cars, because it is BAD LUCK!). Among many other issues, it had bad rings.

Its hard to say from an internet board, a video would be particularly helpful and maybe it can compared to another's car. As was said, internal combustion piston engines do not seal 100% and the crankcases will get some positive pressure as 'blow by". However, worn out engines get a LOT of blow by. Diesels have more pressure so more blow by, but I'm not sure with info folks have a determination can be made as to the condition of the engine. If it has good power, that's a good sign.

I'm happy to explain this one...

HDIs have just as much blowby- remember, too, that the vacuum pumps exhaust into the crankcase on both.

But here's the reason for your observation: HDIs and all other PSA engines since 2001 or so have the dipstick tube extended into the base of the sump, to allow for vacuum extraction of the oil.
If there was sufficient crankcase pressure, it would pump the oil out through the open tube, but at normal pressures the oil in the sump seals the bottom of the tube.

simples!

i don't know if i'll manage to get a video, kind of unlikely.
DPM: very informative, that explains why our xsara doesn't do anything out the dipstick hole.
Anybees: your engine does the same puffing whilst idle and then stops whilst revving?

Well the mechanic was some 15~ city blocks away in moderate to heavy traffic at ~ 20+°C outside in sunny day, so i guess it should have been warmed up enough

So, resuming what you guys tolds me:
1) it should puf whist idling, but as soon as i rev it it should stop(if it continues then i can say it's bad rings?).
2) it should also puf more whilst cold

but i'm also worried as n4s said, that it has broken rings...
What i'm going to do is check other same year TDI passats in other dealers and see if they do the same....

I would check rings with a compression test, not the dipstick.

That's for checking oil.

KLXD i thought of that but it's kind of involved, i should call the VW dealer that did the service to see if they have the tools available to perform that onsite

If a Vacuum pump is pushing that much air into the CCV system, there must be one 'ell of a vacuum leak somewhere.......... I've read that comment numerous times. The Vacuum pump exit air (very very very small amount if no vacuum leak) is nothing compared to the usual normal blow-by........it's virtually a non-issue!

Dip stick tubes on all the vehicles I have ever owned always extended into the oil pan area somewhere close to the bottom of the block .......nothing new there!

As suggested, to rule out rings as a possible problem, do a compression check!

hmmmm i'm getting some very conflicting info you guys are posting.., and a lot of theoretical stuff...

some say this is normal, some say it's the vacuum pump, then other says it can't be unless a vac line is broken, some others say the dipstick doesn't go to the bottom of the sump, then other say it does...

so, the most important thing seems to be missing: can someone visually verify if their 2.0 TDI engine(specially ~2006 model) does indeed fume(puf puf puf) whilst idling with their own eyes?(and if it keeps doing so after revving)

About the comp test, i've talked to one of the 2 official VW dealers(with service) and the sooner they can look at it is ~oct 13th for a 24 point inspection +comp+turbo test

Find another similar TDI near you and see if it does the same thing.

Bill

i am trying that as well, but it's not very easy to find them...

went to see a same year, same engine vento (oh yeah, jetta as you call it), it doesn't fumes AT ALL, not even pushes hot air.
and the engine was noticeable quieter as well

If your engine starts-up pretty good (not lots of cranking), then I'd say the compression is probably within specification.

I'd first check the CrankCase Ventilation system on top of the valve cover (top of engine) to make sure it is not plugged with crud.

Here are a couple of photos of the "bottom end" of an ALH engine 1.9. You can see the end of the dip stick.......indication that the Dip Stick tube (funnel) goes to the bottom of the engine block.......right where there would be lots of blow-by fumes/smoke.

In this photo, the dip stick is visible in the back ground.............


In this photo, the dip stick is very obvious.....

...but as I said, PSA extend the TUBE to the floor of the pan; no chance of fumes to get past three or four inches of oil...

Mine just shot oil all over me

The fact the engine smokes is not the issue. The fact it runs unevenly, now THAT is an issue. I don't believe the car salesman.

If you had anyone hook up the VCDS to the engine, block 13 would probably tell it all. If the valve cover were removed, that would probably tell the rest of the story. I think it may have more than one issue, but I suspect the cam is worn out. At 75k, that would not be normal, but it wouldn't be the first with 'questionable mileage'.
If not that, the injectors are expensive to replace. One way or the other, a VAG-COM software program is the ONLY way I know to check some of this stuff without major dismantling.

The simple 'redneck check' is to loosen the oil cap and see if the cap wants to blow off. I agree, some blowby is normal. The cap blowing off is not. If there is oil spatter blowing out the hole, that's too much for me...Also, it seems there is a distinct 'puffing' where one stroke shows a greater volume of blowby. That could be rings or a bad injector, maybe both. At that point, believe your first mechanic and move on.

I'm getting the pulsing blowby from the oil cap and and splatter.

How would a bad injector cause blow by? Do you mean bad injector seals?

PS my engine runs smoothly. Little oil consumption.

Franko6 said:

The fact the engine smokes is not the issue. The fact it runs unevenly, now THAT is an issue. I don't believe the car salesman.

If you had anyone hook up the VCDS to the engine, block 13 would probably tell it all. If the valve cover were removed, that would probably tell the rest of the story. I think it may have more than one issue, but I suspect the cam is worn out. At 75k, that would not be normal, but it wouldn't be the first with 'questionable mileage'.
If not that, the injectors are expensive to replace. One way or the other, a VAG-COM software program is the ONLY way I know to check some of this stuff without major dismantling.

The simple 'redneck check' is to loosen the oil cap and see if the cap wants to blow off. I agree, some blowby is normal. The cap blowing off is not. If there is oil spatter blowing out the hole, that's too much for me...Also, it seems there is a distinct 'puffing' where one stroke shows a greater volume of blowby. That could be rings or a bad injector, maybe both. At that point, believe your first mechanic and move on.

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