blowby

[Zulfiqar]

whats up with this blowby thing

my 1.6 TD engine which has good north of 420 psi compression has some white blowby at idle (engine hot) and then goes away when revved - same thing with my freinds old 5 cyl mercedes and new C220 CDI mercedes. - even my Honda Accord gasser has blow at idle and then nothing at 2000 rpms.. and it has good 180 psi compression in all holes

Some mechanics here say that a good diesel should have no blowby at all, Are they right?? coz half the time they are trying to nick money from your wallets.

Any ideas - btw all the engines mentioned above burn extremely little dino oil - maybe less than half a litre per 1000 kms.

[ObscuredByClouds]

Might be improper atomization of fuel (injectors re-furbed) or the headgasket could be seeping (I doubt it though).

[Pre95]

Might be improper atomization of fuel (injectors re-furbed) or the headgasket could be seeping (I doubt it though).

2nd, time for some new injectors, or double check the fuel load adjustment.

On my 81 it used to have a lot of white smoke @ start up, once I adjusted the fuel to where I *believe* it is supposed to be (felt peppier, touch of gray smoke @ WOT) the start up smoke went away. I have a new set of injectors that will be going in shortly, we'll see if that changes anything about the tuning or running condition.

[Rabbit on Roids]

dude, my 1.5 has so much blow by that it pressurizes the crank case under boost. dont worry about blow by until it starts running away on the blow by.

[rabbitman]

Might be improper atomization of fuel (injectors re-furbed) or the headgasket could be seeping (I doubt it though).

2nd, time for some new injectors, or double check the fuel load adjustment.

On my 81 it used to have a lot of white smoke @ start up, once I adjusted the fuel to where I *believe* it is supposed to be (felt peppier, touch of gray smoke @ WOT) the start up smoke went away. I have a new set of injectors that will be going in shortly, we'll see if that changes anything about the tuning or running condition.

The fuel screw cannot change the idle fueling without the idle speed changing.

whats up with this blowby thing

my 1.6 TD engine which has good north of 420 psi compression has some white blowby at idle (engine hot) and then goes away when revved - same thing with my freinds old 5 cyl mercedes and new C220 CDI mercedes. - even my Honda Accord gasser has blow at idle and then nothing at 2000 rpms.. and it has good 180 psi compression in all holes

Some mechanics here say that a good diesel should have no blowby at all, Are they right?? coz half the time they are trying to nick money from your wallets.

Any ideas - btw all the engines mentioned above burn extremely little dino oil - maybe less than half a litre per 1000 kms.

I don't think any diesel diesel can have zero blowby like those mechanics are saying.

[maxfax]

To the OP, where are you noticing this blowby???   From the tailpipe or the oil fill/breather???

If from the oil/cap breather some will always be present..   I haven;t seen an engine yet that has ZERO blowby..  Some will have very little, and almost appear to have nothing..  With the diesel it is more noticable since there is no PCV system to speak of..   With your oil consumption as low as it is, and compression where it's at don;t get too worried..  Just make sure the breather tube from the V/C to the intake is clear and properly connected...

If you are seeing this white smoke from the tail pipe then the above suggestions is where you need to look...

[Zulfiqar]

this blowby I mention is when you take off the oil filler cap - At the tailpipe on my 1.6 Ive got

black puff at start
clean exhaust on light accelerator
light gray powdery exhaust WOT engine revving nearly 4000
no white at all in any condition

Exhaust system is the original VW one

[rabbitman]

The white smoke at idle is not right, tho.  As mentioned the injectors might be bad.  It could also be injection pump or cam timing.

I think he meant white smoke coming out the breather

[Zulfiqar]

yeah I meant the breather, its not thick white, its kind of like a very light hazy white thing that goes away as soon as you rev

[maxfax]

That's just your normal blowby gasses, and probably small amounts of moisture..  Sounds like your engine is working pretty normal...

[Rabbit TD]

this blowby I mention is when you take off the oil filler cap - At the tailpipe on my 1.6 Ive got

black puff at start
clean exhaust on light accelerator
light gray powdery exhaust WOT engine revving nearly 4000
no white at all in any condition

Exhaust system is the original VW one

It sounds to me like it is exactly what it is supposed to be doing.

[arb]

Some mechanics here say that a good diesel should have no blowby at all,

Since EVERY internal combustion engine has _some_ blow-by (it is not possible to have 100% perfect seals - rings have gaps, round it not absolutely round, etc) it would be very interesting to see a video of all these diesel's they are telling you about that have zero blow-by. ;-)

Yeah, they are trying to part you with your cash !