3t/2tg blowby.

[shelldrake]

Hey guys,

On my hybrid There is a blanking plate on the block where the "pcv" thingy went once. It is blanked from factory on the 3t block I believe.

Off the cam cover I initially had a supercheap mini air filter. When this started spewing out quite a bit of oil I ran a tube to a catch can with a filter on top. Now this filter spews oil.

Some people I have spoken to have suggested I simply run a tube from the top of the cam cover to my inlet manifold, suggesting this would pull the rings out to cylinder walls. - end story. I dont like the idea of a significant amount of oil passing back into my inlet. I have very little understanding of the fuction of the pcv that was initially on the 2tg blocks - But I think this is what I require to stop the mass amount of blowby. Is this the solution? Other people I have spoken to just run catch cans, but I would like to know if this is actually how it should be setup best.

[MWP]

Having a vacuum in the crank case is always a good thing.
It does reduce blow-by by making the rings seal better, decreases oil contamination & helps prevent oil leaks from gaskets/seals/etc.

The is the setup you want:
cam cover -> pcv valve -> catch can -> inlet manifold.

Make sure the catch can is the type that has one inlet, one outlet and a drain bolt on the bottom.
The ones that have the air filter on top are useless.

[shelldrake]

Thanks MWP. So, I shall track down a 2t pcv valve and connect as suggested. Cheers.

[jfallen]

The is the setup you want:
cam cover -> pcv valve -> catch can -> inlet manifold.

What about on a different motor (say, cough CA18DET)

cam covers -> catch can -> sump/with a ilter on top of the catch can to let it vent the crank case gas..

I know it's not immisions legal, but pfft to that. This is what I'm planing to do to mine once i get back to Adelaide. Will also be tapping a small hole in the back of the port side cam cover and running a line to the sump to assit oil drainage out of the head.

Jordan

[shelldrake]

Interesting...

[MWP]

cam covers -> catch can -> sump/with a ilter on top of the catch can to let it vent the crank case gas..

Problem is that doesnt create any vacuum in the crankcase, so you miss those benefits for no real gain of that setup.

[jfallen]

in a turbo application, though, having it connected to the inlet manifold will 'increase' cranck case pressure.

the PCV is basically a one way valve, the only real way to generate negative cranck case pressures is via a dry sump system, where the oil pump is located externally and you basically suck the oil/air out of the motor.

Vent to atmo on turbo cars, and have less issues with your intake getting coated in oil at high loads

Jordan

[MWP]

in a turbo application, though, having it connected to the inlet manifold will 'increase' cranck case pressure.

Not so, thats what the PCV is for.
During idle or deaccel the inlent manifold is in a vacuum which is when the drity crank case vapors are removed.

the PCV is basically a one way valve, the only real way to generate negative cranck case pressures is via a dry sump system, where the oil pump is located externally and you basically suck the oil/air out of the motor.

Or to use a special crank case pump like they do in nascar.
But yeah, your right there.

Vent to atmo on turbo cars, and have less issues with your intake getting coated in oil at high loads

If your still getting oil into your intake after the catch can, then obviously the catch can isnt working properly...

[Turdinator]

Somethings i found the other day whilst bored at work.

Link 1
Link 2

This is what i was talking to you about the other day Ed.

But for others who weren't there. It worries me that by creating a hybrid 3/2TG you block of the crank case ventalation on the 3T block, with the 2TG head. As on 2T and 3Ts the crank case vents through the push rod tubes to the rocker cover, then out a tube and into the carbi/airfilter. On a 2TG there is ventilation on the side of the block, as the twin cam covers the push rod tubes. See above links for diagrams.

[merc-blue]

hmm intresting i have never seen the 2 pictures side by side,
heres a idea i may be WAY off,
but i assume most of us are using electric pumps,
why not use the old fuel pump hole fab up a block off with a vent/PCV valve


Sidenote:
does the PCV system actually prevent blow by or just recycle it?
would a PCV valve -> oil air seperator -> intake and
Rocker -> oil air seperator -> intake
so that both are vented, dirty oil vapor removed and then air returned back to intake, or vented to atmo (as the "air" isnt halping your engine)

[jfallen]

If your still getting oil into your intake after the catch can, then obviously the catch can isnt working properly...

quite right, or it's full.

but I was refering to having no catch can.

Cheers
Jordan

[MWP]

does the PCV system actually prevent blow by or just recycle it?

recycle it. you cant stop blow-by completely.

would a PCV valve -> oil air seperator -> intake and
Rocker -> oil air seperator -> intake

They are the same thing??
PCV valves go between the cam cover/block and the oil catch can.

so that both are vented, dirty oil vapor removed and then air returned back to intake, or vented to atmo (as the "air" isnt halping your engine)

PCV system doesnt work if there is no vac to pull the dirty air out of the crankcase.
Hence why venting PCV at all (even after air-filter & catch can) is illegal.

Any catch can you with an air-filter on top of it is wank... it means the PCV system isnt working properly and is illegal.

[Turdinator]

So the ideal is to have a vacume in the crank case right?

I'm sure i've read somewhere that the airpumps used on emission vehicles make for good vacume pumps. So if you could rig up the air pump to the crank, via an oil air separator/catch can, this would be a good solution?

If you were to do this where do you guys think the best place to 'suck' from would be? Drill into the block where the 2TG pcv valve goes. As i'm sure my 13T (same as a 3T) block has the mounting holes there. Or do a custom 'suck point' elswhere?

[MWP]

So the ideal is to have a vacume in the crank case right?

I'm sure i've read somewhere that the airpumps used on emission vehicles make for good vacume pumps. So if you could rig up the air pump to the crank, via an oil air separator/catch can, this would be a good solution?

Yeah, but im sure its not that simple.
For example, youll need some sort of pressure regulator.
If your serious about it, youll need to do a lot more research.

If you were to do this where do you guys think the best place to 'suck' from would be? Drill into the block where the 2TG pcv valve goes. As i'm sure my 13T (same as a 3T) block has the mounting holes there. Or do a custom 'suck point' elswhere?

Use the stock cam cover points.

[The Witzl]

i have my 18R-GE PCV system setup pretty much exactly as per the 2T-G stock system...

INTAKE AIR (in front of TB) -> CAM COVER -> BLOCK VENT -> INTAKE MANIFOLD

This means air is sucked from in front of the TB, thru the crank, out the crank vent and into the intake.... taking the dirty oil vapours with them.

This is how it was meant to be from the factory