bad blow by

[JasonGilholme]

A catch can won't pick up oil that is part of the blow by.

The catch can picks up oil that the oil seperator hasn't been able to get. Blow by is a result of poor piston ring to wall clearance.

have a compression test done to see what cylinders are down on pressure, and have it rebuilt accordingly if needed.

Once you've stopped blowing oil into the chamber and all over your plugs and valves you'll be able to get a better tune cause there won't be any oil in hibiting the combustion process.

Jase

[ginganggooly]

I'm wondering how a b-series with 75k km could suffer from blow by. How long have you had the car for??

I'm with the other guys here, go get a leakdown and compression test done...

I have thrashed the living sh!t out of my car for the last 200k km (now has about 260k km on the clock), and having replaced a clogged pcv valve, the oil consumption is pretty decent, about 1L/5000km.

[tinkerbell]

you say you have "blow-by"

but all i can see why you think this is due to your oil level going down...

you need to expalin more of why you think you have a blow-by issue on a 75'000km old engine...

[silver_screen]

that curve looks alrite to me
very flat torque curve.. 12.8 isnt rich.. sounds about right but he could get a bit more power uptop.. somethings not completely right

[JasonGilholme]

I'm wondering how a b-series with 75k km could suffer from blow by. How long have you had the car for??

I'm with the other guys here, go get a leakdown and compression test done...

I have thrashed the living sh!t out of my car for the last 200k km (now has about 260k km on the clock), and having replaced a clogged pcv valve, the oil consumption is pretty decent, about 1L/5000km.

My b16 has 140k on it and it doesn't blow smoke at all. No oil consumption either. i put in 4 litres and take out 4 litres each time i change the oil.

[BlitZ]

Please explain... then what does it pick up?...

my understanding
Oil separator is used to separate the oil in the blow by... honda has OEM separate called PCV..

PCV is ok.. but when there is alot of oil the oil still gets back to the head... so thats is the readson we run cathc cans

A catch can won't pick up oil that is part of the blow by.

The catch can picks up oil that the oil seperator hasn't been able to get. Blow by is a result of poor piston ring to wall clearance.

have a compression test done to see what cylinders are down on pressure, and have it rebuilt accordingly if needed.

Once you've stopped blowing oil into the chamber and all over your plugs and valves you'll be able to get a better tune cause there won't be any oil in hibiting the combustion process.

Jase

[tinkerbell]

I agree with BlitZ

it is the role of the PCV system (which involves the oil separator) to remove "blow by" gases and other substances like water and unburned fuel from the crank case.

a additional catch can augments this system and when set-up correctly , can completely prevent the ingestion of non-vaporised substances into the combustion process...

[JasonGilholme]

It doesn't seperate oil IN the blow by. But it does seperate the oil from the air in the crank case before it goes back into the combustion chamber.

The crank case is vented from the back of the engine and goes through the PCV then up into the intake manifold.

Blow by is where your piston rings aren't making a sufficient seal up against the cyllinder walls and oil is getting past. If the PCV valve worked on "blow by" it would mean that all cars would have poor piston ring to cylinder wall clearance from factory.

i hope this helps.

J

PS: I think ben has a good diagram which explains where the PCV system runs.

[tinkerbell]

how does that help?

you said:

A catch can won't pick up oil that is part of the blow by.

we said, yes - it will, that is what a catch can does...

[tinkerbell]

here are some links for you:

http://en.wikipedia.org/wiki/PCV_valve

http://www.honda-tech.com/zerothread?id=1199935

[DLO01]

Hi Comp, you say its Blow By, but I am not convinced the actual problem is Blow By.

[tinkerbell]

It doesn't seperate oil IN the blow by. But it does seperate the oil from the air in the crank case before it goes back into the combustion chamber.

The crank case is vented from the back of the engine and goes through the PCV then up into the intake manifold.

Blow by is where your piston rings aren't making a sufficient seal up against the cyllinder walls and oil is getting past. If the PCV valve worked on "blow by" it would mean that all cars would have poor piston ring to cylinder wall clearance from factory.

after trying to work out what you are saying - i need to ask:

do you realise that "blow by" is where the cylinder pressure rushes past the piston rings INTO the crank case? not the other way around?