Oil catch can

DMan

shawly the least hangeriest guy on rotorburn
Hey Dman have you checked to see how much oil it goes through in between services?

What a lot of you blokes don't realise is that the car is tuned to cope with oil vapours as part of the emission control system, Fair enough if the car has a serious problem with piston blowby but I wouldn't put a catch can on for the sake of it. I can tell you now it will not stop gas reversion from valve overlap depositing carbon gunk on the back of the valves. The only thing you can do there is use fuel additive cleaner from the start of owning the car.

https://www.outbacktravelaustralia.com.au/4wd-mods-powertrain/diesel-fiddles-may-2016
Hardly anything Flow. It doesn't smoke and I don't need to top the oil between services. So I'm thinking it can only be a relatively small amount if the level isn't dropping on the dipstick?
 

Dales Cannon

lightbrain about 4pm
Staff member
Modern common rail diesels produce blowby from day 1 and it isn't because the rings are munted. I bought a Provent copy and it was shit, capacity was smaller, filters weren't interchangeable and the original filter medium was shit. As long as you plumb the catch can back into the ontake it is legal. Keep an eye on oil levels and drain regularly.
 

Flow-Rider

Burner
Hardly anything Flow. It doesn't smoke and I don't need to top the oil between services. So I'm thinking it can only be a relatively small amount if the level isn't dropping on the dipstick?
Yeah, It will be bugger all oil if it's not dropping on the dip stick. I just don't get the need for it on a relatively new car, you might want to put one as a preventive maintenance for the future.

I've removed lots of intercoolers on turbo diesels, new and old cars that have had a small amount of oil in them. We used to run kero cleaner through the inlet manifold and inter cooler as part of the service if we needed to do any major work on the engine like a head gasket and customers didn't notice any difference with the engine performance from when it was previously running good.
 

Flow-Rider

Burner
Modern common rail diesels produce blowby from day 1 and it isn't because the rings are munted. I bought a Provent copy and it was shit, capacity was smaller, filters weren't interchangeable and the original filter medium was shit. As long as you plumb the catch can back into the ontake it is legal. Keep an eye on oil levels and drain regularly.
All piston driven motors have a certain degree of blow-by gases, it's just on diesels you get more ( Higher compression ratios) and by adding forced induction you get even more again. As diesels get older, you get what's called 'bell mouthing' in the top of the cylinder bores and the efficiency of the piston rings to seal against the cylinder bores fall. I've also seen where people have used the wrong grade oil, it glazed the bores and they ended up with oil usage and lower compression rations.
 
Last edited:

DMan

shawly the least hangeriest guy on rotorburn
All piston driven motors have a certain degree of blow-by gases, it's just on diesels you get more ( Higher compression ratios) and by adding forced induction you get even more again. As diesels get older, you get what's call bell mouthing in the top of the cylinder bores and the efficiency of the piston rings to seal against the cylinder bores fall. I've also seen where people have used the wrong grade oil, it glazed the bores and they ended up with oil usage and lower compression rations.
Thanks Flow. At this stage I'll just keep an eye on things then.
 

Haakon

has an accommodating arse
All this catch can talk reminded me the Alfa really needs one... It’s a very highly boosted engine (170bhp from a 1.4).

Popped the engine cover off and staring back at me is a factory oil separator that just drains back into the valve cover! Nice :)

 

Dales Cannon

lightbrain about 4pm
Staff member
Can you please confirm which bit is nice?

Think we have a different idea of what constitutes highly boosted, 400+bhp from 2.8L is normal and I am looking for more....
 
Last edited:

Haakon

has an accommodating arse
Can you please confirm which bit is nice?

Think we have a different idea of what constitutes highly boosted, 400+bhp from 2.8L is normal and I am looking for more....
Jeez, call yourself a car nut and don’t recognise a factory PCV oil separator system...? Tut tut.

For a factory system, 18-22psi is pretty high. Although the 0.9 three cylinder Clio I had ran 30psi.
 

hifiandmtb

Sphincter beanie
@Dales Cannon Avatar is a BMW M2, it's a 3.0l hence me asking! (you said you had a 2.8l).

Fun fact: My mate has an M2 now, did have an M135i that I loved. It was rather more practical!
 

Flow-Rider

Burner
All this catch can talk reminded me the Alfa really needs one... It’s a very highly boosted engine (170bhp from a 1.4).

Popped the engine cover off and staring back at me is a factory oil separator that just drains back into the valve cover! Nice :)

Does that steel pipe join to the tappet cover ?
 

Flow-Rider

Burner
Can you please confirm which bit is nice?

Think we have a different idea of what constitutes highly boosted, 400+bhp from 2.8L is normal and I am looking for more....
My mate has one of those and close to that figure normally aspirated, I think you might know him (Pierz)
 

Haakon

has an accommodating arse
Most of these modern “downsized” turbo engines have the wicked turned up pretty high... Makes them a bit laggy, but they get along pretty well. The G isn’t a terribly light car, but it’s 1.4 is pretty motivating!!

The Clio was pulling 66kw out a 900cc triple - it went waaaaay better than it should have :)
 

Dales Cannon

lightbrain about 4pm
Staff member
I like modern turbo engines. The ones I have driven are not at all laggy, well compared to the 80s and 90s turboed engines anyway.

Boost pressure isnt meaningful on its own, depends on compression ratio.

My thing dips now into the high threes to get to highway speeds. That isnt too shabby. The Guilia is a bit tubby, surprised at that!
 

Haakon

has an accommodating arse
Mine is a guilietta, not the Giulia - Guilia gets a 2 litre or the glorious V6 which is a Ferrari California V8 with two pots chopped off.

It’s 1.4 is pretty snappy in sport mode, the “normal” mode is a bit doughy though.

The Clio 0.9 was very highly strung - it was a gutsy little thing on boost but could be caught off.
 
Top