Technical Is this normal?

[Elvis21]

Is there a lack of air? or a lack of pressure?

 

[Elvis21]

?

 

[Zardo]

Your question could be more precise. What are you inquiring about?

On a working internal combustion piston engine, it's normal to have blow-by gases. These go first to the crank case, they need to be evacuated otherwise the joints will blow out. It's possible to estimate the normal volume of the blow-by, and it becomes quite important if the engine is revving. Opening the oil cap on an active engine always produces some mist. There can be excessive blow-by if the piston rings are done for. But then you would probably also have a loss in compression, power, high oil consumption and some blue smoke on the exhaust.

 

[Elvis21]

the oil filler cap, she pulls it. it loses oil and at idle it emits blue smoke

 

[Zardo]

So you have some negative pressure in the cylinder head crankshaft area, an oil loss and blue smoke.

You didn't state what engine it is, like 1.4 16V, 1.4 16 V T-jet, it doesnt look like diesel or multi-air to me. There are Euro-4 and Euro-5 versions.

This is for Bravo 198 1.4 litre 16V T-Jet:

The gases coming from the crankcase rise to the cylinder head and are then directed to a separator which has a diaphragm which allows:

- the condensation and collection of the vapours

- the absorption of the vapours in the intake circuit for their combustion.

The system is equipped with a pipe for the intake of vapours connected to the air chamber and a pipe connected to the turbocharger intake.

This makes it possible to:

- during supercharging, send the vapours via the duct (3) to the turbocharger intake

- during idling or release, send the vapours to the duct (2) connected to the air chamber, downstream of the throttle.

Could be a problem with the air/oil separator and PCV System (positive crankcase ventilation system).

There is a video which shows one which is totally blocked:

 

[Elvis21]

1.4 t-jet. I changed the turbo and two PVC valves to be safe.
I want to be sure before I change the piston rings and valve seals.

 

[Zardo]

I edited my citation. In case you've already cleaned the air/oil separator and its membrane, I don't know how resistant that membrane is to, for example, brake cleaner or acetone. Depends how you've done it. An intact membrane, correctly fitted, is important for the correct function of the air/oil separation and PCV system.

Maybe re-check the air/oil separator and it's tubing. In addition, you could do a compression check on the cylinders just in case there is a loss of compression with, maybe, excessive blow-by. However, if there was excessive blow-by, I'd rather expect blow-by gases coming out of the oil cap hole, I would expect positive pressure in the space under the tappet.

Also, someone else might be able to help you more on this case, as I'm not a professional.

 

[Elvis21]

I installed a new PCV.

The pipe coming from the intake manifold to the PCV requires a lot of air while it is being compressed. I don't like this. The car runs perfectly.


thank you very much

 

[Zardo]

I installed a new PCV.

The pipe coming from the intake manifold to the PCV requires a lot of air while it is being compressed. I don't like this. The car runs perfectly.


thank you very much

I asked ChatGPT because I suspect that, for some reason, the gases are sucked into the vaccum intake manifold with the engine idling in your case. With the engine idling, they shouldn't go there, they should go to the air chamber.

Take this with a grain of salt:

A faulty membrane (diaphragm) in the described crankcase ventilation system of a Fiat 1.4 16V T-Jet engine could potentially lead to excessive vacuum in the camshaft area (the space under the tappet cover). Here’s why:

Function of the Diaphragm​

The diaphragm in the separator plays a critical role in regulating the flow of crankcase vapors to the intake system, depending on engine operating conditions:

1. Idle or deceleration (high manifold vacuum): Vapors are routed through the pipe connected to the air chamber (downstream of the throttle) to maintain appropriate pressure balance.
2. Boost conditions (low manifold vacuum): Vapors are redirected to the turbocharger intake pipe to avoid excessive vacuum in the crankcase.

Consequences of a Faulty Diaphragm​

If the diaphragm becomes damaged or stuck in a way that fails to properly regulate the crankcase ventilation:

• Excessive vacuum in the crankcase can occur during idling because the intake manifold vacuum is high, and the faulty diaphragm may not provide sufficient resistance or balance.
• This excessive vacuum could draw air and oil mist from the crankcase and camshaft area, leading to:
  • Oil leaks: Seals and gaskets may be pulled inward, leading to leaks or even failure.
  • Performance issues: The improper flow of crankcase gases can affect the air-fuel mixture and combustion process.
  • Noise or abnormal behavior: A malfunctioning diaphragm might produce a whistling or sucking noise due to air being improperly drawn.

Diagnosis and Verification​

1. Check vacuum levels in the crankcase using a vacuum gauge connected to the oil filler cap or dipstick tube while the engine is idling. Excessive vacuum suggests a faulty diaphragm.
2. Listen for unusual noises: A damaged diaphragm often produces noticeable sounds.
3. Inspect for oil leaks around seals or the separator itself.

Suggested Fix​

If you suspect a faulty diaphragm, it’s typically part of the crankcase ventilation system or oil separator assembly and needs to be replaced as a unit. Ensure all related hoses and connections are free of blockages or leaks to prevent further issues.

 

[Elvis21]

This makes me very confused.

 

[Zardo]

did you actually replace the whole air/oil separator or just the PCV valve?

I didn't know that one could buy the PCV valve separately, but it appears there are non OEM aftermarket PCV valves available.



When I cleaned my air/oil separator on my 2010 Punto 1.4 multiair turbo, there was this big membrane as in the video in post Nr. 5. But you talked about 2 PCV valves. Maybe you bought a newer part which is not compatible with your engine?

 

[Elvis21]

PCV-ja e re ishte një produkt origjinal i Fiat-it. Dyshova dhe bleva një tjetër të përdorur.

 

[Zardo]

There is definitively too much vacuum when the engine is idling. The vacuum most likely comes from the vaccum part of the intake manifold (before the turbo). This will result in too much oil vapour sucked into the intake, and might cause blue smoke when idling.

Your picture: the lower connection is the vapour supply pipe at supercharging speed and connects to the turbocharger air intake hose; whilst the upper connection is the vapour supply pipe at idle speed and connects with the air chamber.

Too much vacuum at idle could be resulting from a malfunction of the flow switching diaphragm (the membrane with the spring), for example if the membrane is incorretly mounted inside after cleaning, if the spring was forgotten or is broken. I remember that I had to look at my pictures taken when removing it to be sure how to fit it back in before closing the cap (which was actually quite cumbersome to open in the first place). So if you've fitted a used air/oil separator, better check if the membrane (the flow switching diaphragm) is correctly mounted inside.

The other reason of too much vacuum could be switching the connection tubes, but they have differing lenght, I would find that highly unlikely.

Hope this helps

 

[Elvis21]

should I get a third PCV? I'll take another look. Thank you very much for your dedication.

 

[Elvis21]

I removed the pipe from the pcv to the intake manifold. The car didn't smoke.

 

[xarenwo]

Hi, did you solve anything ? My pipe from PCV to intake manifold cracked (it was old) and it was also collapsed like yours. The car consumed 450ml of oil in 1000km, and before that I had faulty pcv valve and it was consuming 200ml/1000km. After replacing the pcv (completely new not just membrane) it was consuming around 100ml/1000km but then the hose from PCV to intake cracked and I did not notice when, I just noticed now, but sometime in the past month, the oil consumption increased by a lot. I don't have blue smoke from the exhaust in any condition though, no smoke at idle, no smoke during acceleration, no smoke in any situation, but 450ml/1000km is a lot and I don't suspect the piston rings or valve seals because that would not happen in 1 month and 1000km, and it would be consistent, it would not be 200ml/1000km then after new pcv 100ml/1000km and now 450ml/1000km. Turbo is old but no oil in the cold part that goes to intercooler. There is a lot of vacuum on that line from intake to pcv for me too. Could it be the new pcv valve broke already ? There are no oil leaks anywhere, I got the car 4 months ago, it had 158000km, just did the clutch and flywheel and made the car new (suspension,brakes, rocker cover gasket, oil seals camshaft &crankshaft, everything basically). Now I added oil back to full and I'm waiting to drive at least 1000km to see if the oil consumption was due to the broken pipe that was pulling false air in or loosing vacuum. Did you fix it in the end ? Thanks

 

[Elvis21]

I haven’t fixed it yet. The car consumes 600–700 ml of oil per 1,000 km. I checked the compression on all pistons and they were fine. However, I found traces of oil on the first piston.

 

[Mike1alike]

I found traces of oil on the first piston.

Just on the first cylinder spark plug or is that the only one you've checked?!
Probably all the spark plugs look the same and the cause is valve seals, as I've told you in the new topic you've opened.

 

[Elvis21]

Only the spark plug of the first cylinder is like this, the others are clean

 

[Mike1alike]

And the compression on cylinder 1 is ok?
I think we should talk about this in your othe topic, to be al in one place. I'll copy these las messages there, too. Reply there, please.