breather fumes

[gherlt]

Hello experts,
in solving my car problems (so many !!) today I came to a (new) crossing with the S4.

On my S3 - 8/10 years ago- they routed the block vent into a Tudor bottle located in the nose, it works fine and I have only emptied it once, and not much dirt was inside.

My S4, which has a much more tired engine, lets out a much larger volume of block fumes, on the motorway on WOT I can see leaving quite a white cloud behind. The block will be rebored sometime soon, but meanwhile I would like not to cause so much attention, so I bought a nice round oil catch can from OBP, to be located in the nose, and thought that could be the solution.
I just tried it out and even if the fumes are less "dense", still a lot come out.
Now, I see three options:

1- bring back the remaining fumes to the airbox and use the breather tube inlet and "burn" them
adv: no mods; cheap
disadv: more backpressure in block due to long tube ?
all fumes go to cyl. no. 4 again

2- put on a Vent Air Filter (like KN 62 1010) on the oil catch can, the filter should do the work
adv: cheap
disadv: how long will filter last ?

3- Make a hole in the air filter box or in the air hose and blow into it, so fumes will dispatched to all 4 cylinders
adv: not all goes to cyl. 4
disadv: making a hole where there shouldn't be one ...

Any suggestion ? Comments ? Thanks ...
Cheers
Guillermo

[elans3]

Slightly confusing as you mention a "white" cloud of smoke. Oil burning is blue.
White can only mean one of two things, steam (usually head gasket failure or a cracked cylinder head), and you should notice some overheating and water loss if that were the case, or, if the car is running a servo, a failed servo (brake booster), and the white smoke is brake fluid being burned. (sucked into the inlet manifold & burnt off through the exhaust.). Are you positive that it's crankcase fumes, and should be blue smoke ? ?

[gherlt]

Hmmm, now that you mention it ...
Brake servo is new.
There is not water in oil to be seen from dipstick check. But then, oil is very new (150km?)
Engine has not been running for months, so maybe water within block due to humidity.
I will check water level, did not think about that.

[gherlt]

Nonetheless, independent from current fumes origin, which of the above solution is preferable ?

[ericbushby]

Good morning gherit.
Another simple check is to remove the oil filler cap. You may find white oil/water emulsion which looks a bit like mayonaisse on the underside. That is what I am working on just now.
Hoping it isn`t
Eric in Burnley
1967 S3SE DHC

[rgh0]

if you are not doing it use a high quality full synthetic oil. This smokes less ! Going to a 20W-60 will also reduce leakage into the cylinders and lessen burning

cheers
Rohan

[Craven]

Comments about adverse effects on returning the engine breather to the airbox, if real, could be overcome by a simple distribution pipe within the airbox itself. A perforated pipe running along under the trumpets should be sufficient, ensuring there is no increase in resistance to flow. Perhaps a series of graduated holes along the pipe would improve distribution.
FWIW.

[2cams70]

You need to give the engine a compression test to find out the general condition and you also need to disconnect the brake servo and plug the connection. Run the engine in this state to isolate the servo as a potential case.

If the servo is ok fumy smoke under continual hard acceleration is generally caused by bad piston/ring sealing. If you just get a puff of smoke after accelerating hard after a period of the engine coasting or idling under closed throttle conditions this is generally caused by bad valve guides.

[MrBonus]

if you are not doing it use a high quality full synthetic oil. This smokes less ! Going to a 20W-60 will also reduce leakage into the cylinders and lessen burning

cheers
Rohan

Do you have a preferred 20W60? Not many oils out there in that weight.

I'm assuming this is like asking someone what their favorite pizza place is!

[69S4]

if you are not doing it use a high quality full synthetic oil. This smokes less ! Going to a 20W-60 will also reduce leakage into the cylinders and lessen burning

cheers
Rohan

Do you have a preferred 20W60? Not many oils out there in that weight.

There's a few around - these from the local place I get most of my oil from -

https://www.classic-oils.net/Millers-CSS-20w60

https://www.classic-oils.net/Millers-Cl ... 60-5-litre

https://www.classic-oils.net/Millers-CFS-10W60-NT-

https://www.classic-oils.net/Penrite-HPR15

[gherlt]

The engine had a compression test and it was fine.
I wanted to do a compression loss test, but equipment was (and is) not available.
The engine IS worn, the cylinders walls are slick, any signs of previous honing are gone.
The fumes most likely come from the combustion chamber due to the worn sealing,
but nonetheless they are quite "whitish", not blue ...

I will disconnect the brake servo and test that.

[elans3]

As mentioned before, oil burning smoke is definitely blue, brake fluid & water white. You can't get them wrong.
Also, if it is the servo, the sparkplug nearest the inlet manifold servo take off will be white-ish too, completely different from the other three. Had exactly that issue on my Alfa a few years ago.

[2cams70]

The engine IS worn, the cylinders walls are slick, any signs of previous honing are gone.

The fact that the compression test was OK is a positive sign. It doesn't necessary mean the engine is too worn just because the honing marks are gone. Old style engines such as these running carburettors rather than fuel injection usually lose the honing marks in the bores quite early in the engine's life. Poor mixture control from carburettors leads to liquid fuel drenching the bores which increases the wear rate. If you can see the bore wear lip at the top of the piston ring's travel or better still accurately measure the bore precisely with a micrometer this is a more accurate way of determining the wear. From what you are saying about the compression test however I doubt you have much of a problem in this area.

[elans3]

The engine had a compression test and it was fine.

The fumes most likely come from the combustion chamber due to the worn sealing,
but nonetheless they are quite "whitish", not blue ...

I will disconnect the brake servo and test that.

Do you have the numbers from the compression test ?
Like the above, I'd say that no honing marks isn't necessarily a sign of a worn engine, particularly if the numbers from your compresion test are 150 +.

Just one thing, disconnect the servo hose from the manifold joint, not the servo, and cap the manifold fitting off somehow.
Otherwise, if the servo is bad, you'll still be burning brake fluid off for a few miles before it clears (i.e. the brake fluid residue on the inside of the hose from the servo to the inlet manifold)
Let us know how you go.

[gherlt]

I did check the ignition plug on the first cylinder, it was black.
Problem: my elbow stroke the ignition cable out of the plug conector and there are no means to put it back in/on.
So more engine test until arrival of new cables.

More details:
the tube is still a bit long, the fumes condensed inside and out came ... water.
And level of coolant is clearly descending.
No more doubts here.

Buckland says that if the engine has been standing a long time the pump seals could have shrunk/hardened and the water gets down from there.
A much better scenario than the possibility that mentions my mechanic, as the head was repaired recently and the head gasket is a "good one" (and the mechanic also a good one), the side wall of the cylinder could have a leak ...