blowby in nissan hr16de engine.

[shDK]

Hi all.

I often hear people talk about blowby in an engine becouse air is pushed out when removi g the oil fillercap.

My engine, a 4 cyllinder petrol engine also blows air out of the oil filler hole. And a freind are tryin to convince me that my engine is worn out. I uses about 0.5 litres of oil in 10.000 km. And runs perfekt. And have only 75.000 km on the clock. I say it.s completely normal. Who is rigt ? Me or my freind

Søren.

 

[Danno]

I suspect the engine blows air out of the oil filler hole as it does not have to go out the PCV valve and the oil filler hole is an easier place for the air to escape. PCV means Positive Crankcase Ventilation. The engine is designed to blow air and any oil particles through the PCV and back into the engine to be reburned.

No worries on a worn engine - it blows air because it is designed to do it.

 

[Quest]

air-blowing out from your oil filler cap (while the engine is running) and that's normal.

Also: burning 0.5L/10,000kms is mighty fine and well within range for a properly maintained engine.

tell your friend to go sleep early, for sleep-deprivation will definitely cloud his judgement RE: blow-by = worn engine.

Q.

 

[shDK]

Thank you all. I think it.s because he's heard to much about what he call blowby back home (he is american) from people who probertly know very litle about the subject. In Denmark vi call the air being pushed out "undercombustion". And is simply the air push out of the crankcase by the down moving pistons.

But thanks all

 

[KrisZ]

I would still check the PCV and the breather hose to make sure nothing is clogged. I would say this is normal to some extent, depending where the oil fill cap is situated.

Try putting your hand over the fill hole and see if the pressure goes somewhere else, if not and you feel quite a bit of gasses escaping through the fill hole, your breather hose and/or PCV need attention.

 

[shDK]

If you place the fillercap loose on the fill hole. It stays on. And actually feels like it sucks down the cap with a bit of vacume. All pcv hoses are nice and clean. Had the pcv system taken apart last weekend when changing the sparkplugs.

 

[shDK]

And the fillercap is placed in the valvecover.

 

[OVERKILL]

Originally Posted By: shDK
If you place the fillercap loose on the fill hole. It stays on. And actually feels like it sucks down the cap with a bit of vacume. All pcv hoses are nice and clean. Had the pcv system taken apart last weekend when changing the sparkplugs.


Then it is completely normal. What you are feeling on your hand is the pulse of the air being displaced by the pistons going down. What you are not feeling is the suction that also happens when the pistons go up. Since we are more sensitive to the former than the latter, with the pistons in motion, generating pulses of vacuum and pressure simultaneously, we only FEEL the former. This is why there is the "paper test", which involves putting a piece of paper over the opening and seeing what it does.

However, your observations with the fill cap pretty much answer that question, and that is that what you are observing is the proper behavior of a healthy engine with minimal blow-by. If it tried to launch the fill cap, then you'd know you had a blow-by problem.