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Catch can, breather hoses and excessive blowby

Dauntless

The Brapmaster™
Joined
Jun 13, 2004
Location
NSW, Australia
Hi Everyone,

My 90 745T has a fairly worn out B230FT, and a replacement engine is planned. However, it's my daily driver and I need to keep it running for now.

The engine runs well and makes good power, but does have some piston slap.

I recently changed the breather setup and added a catch can. Since then, oil consumption seems to have increased, and the catch can fills up very frequently.

The outlets of the breather box and valve cover meet and run to the catch can, which then vents.

After 200km of highway driving yesterday, it pushed at least 300mL of oil into the catch can, possibly much more. It consumed around 2.5L of oil to drive 400km.

Is it likely that my setup is allowing too much oil to be vented? Or is the engine just so worn out that the stock breather couldn't keep up? The stock arrangement did fill the intercooler with oil.

Any advice greatly appreciated.

Here are some pics of the setup:
IMAG2478.jpg

IMAG2477.jpg

IMAG2479.jpg

IMAG2481.jpg
 
With a stock engine, running normal boost and rpm's, why would you vent the cam cover (did you baffle the inner opening)? That is probably where you are losing all the oil.

Have you done a leak down or compression test? That will more precisely tell you the exact condition of your engine. Did it smoke before or now under load? At idle? Cold starts?

Any VTA setup needs to have lines and all fittings with ID larger than stock (so at least 14mm ID) to prevent restriction. Right angle fittings are also a poor solution unless they are much oversized. Venting the cam cover makes no sense if it's not properly baffled to prevent sloshing all the oil out the tube. Having a drain back to the block from the catch can would prevent the oil loss of course...

I use AN10 fittings, bored out as much as possible with Volvo 949701 breather hose

null_zps293cebee.jpg


1901117_10151904681051370_56745800_n_zps32a22672.jpg
 
With a stock engine, running normal boost and rpm's, why would you vent the cam cover (did you baffle the inner opening)? That is probably where you are losing all the oil.
I think Ash from DVS had previously ran it on his track day car, with no issues. It isn't baffled. How would I go about this? Could I get away with some steel wool in the AN fitting?

Mods are 15G at 15psi and an IPD Turbo cam. 380,000km on the engine.

Have you done a leak down or compression test? That will more precisely tell you the exact condition of your engine. Did it smoke before or now under load? At idle? Cold starts?
I haven't. 60,000km ago when I had the head off, the pistons could be rocked in the bores by hand. I know it needs to be replaced. It doesn't smoke from the exhaust under any conditions that I know of, and didn't before the mods either.

Any VTA setup needs to have lines and all fittings with ID larger than stock (so at least 14mm ID) to prevent restriction. Right angle fittings are also a poor solution unless they are much oversized. Venting the cam cover makes no sense if it's not properly baffled to prevent sloshing all the oil out the tube. Having a drain back to the block from the catch can would prevent the oil loss of course...

I use AN10 fittings, bored out as much as possible with Volvo 949701 breather hose

null_zps293cebee.jpg


1901117_10151904681051370_56745800_n_zps32a22672.jpg
VTA? Your setup looks nice. Unfortunately I wasn't able to find anything nicer than right angle fittings that would fit. I did drill out the ones that weren't full bore internally. I assumed this setup would flow more than stock. I'm using 13mm hose.

If the setup was too restrictive, could it cause more oil to blow out? I wouldn't have thought this was the case.
 
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Yea, if that valve cover opening isn't baffled you are gonna pull a **** load of oil out. You need to install some type of deflector shield in front of that.

If you were filling the intercooler up with oil with a completely stock setup your ish might be so messed up that a catch can wont save you.
 
I'm having trouble finding any good information.

Should I fit some sort of baffle just over the inside of the vent hole? Fitting a baffle to the entire valve cover seems difficult.
 
So there is the hose that goes from the top of the PCV flame trap box back to the inlet across the top of the valve cover. I installed my catch can replacing that and get no oil. Every oil change some dirty water drains from the catch can. The photo does not show the connections, but you can piece in the rest.

 
I recently changed the breather setup and added a catch can. Since then, oil consumption seems to have increased, and the catch can fills up very frequently.


Put it back how it was before?
 
B20 oil cap?

Screw in a baffle below that maybe just because of the oil splashing OHC motor, but I haven't needed to with a coarse something (similar to a scotch-brite pad or maybe the oil resistant foam like pipercross uses for air filters that's breathable in the B20 oil cap), I know it can very effectively precipitate the oil droplets out as the vapors blow thru the oil cap. TB budget friendly, pretty proven to work.

Personally, I'd just do that and Y the hoses together and forget the catch can. Your fitting on the oil trap box looks kind of restrictive as well. I'd just Y them together right before the turbo inlet hose from B20 oil cap with pipercross foam style element in it and oil trap box on the block and be done with it. Could be done cleanly and pretty elegantly. The small hose for high vacuum/low load (light cruise) that runs to the intake manifold directly from the nipple fitting above the factory oil trap box plays a very important role in oil consumption on B230Fts/other sohc red motors that use it (all but B21FT/et IIRC).. I drill out the fitting though, so it is the same ID as the big hose basically. Run the can if you must, I haven't really needed to. Just the above has been enough generally for most hooped out blowby specials. I've done it to a couple tired out old turbos cleanly and it has kept oil consumption at fairly acceptable levels and leaks in check. Easy/cheap.

If the blowby is worse than that minimal effort step can cure, dry sump because you are really force feeding it and making big power with abyse, or replace the engine (more likely whats needed on TB..not that it that happens per se.).

The current setup is basically a perfect oil siphon for oil to literally be pumped off the camshaft directly into the catch can.
 
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Thanks for the info. Where are you suggesting I screw in a baffle? And where would you place the oil resistant foam?

Do you think I'd get an acceptable result by effectively baffling and filtering the oil out of the top hose?
 
The '75 tall B20 oil cap usually has something similar to a pipercross foam air filter in it. It's just...an oil cap with a pipercross air filter inside it...works great! Need pictures?

Earlier ones breathe through the sides of the oil cap and have a baffle in the oil cap, but I'd probably run the gauze filter, it isn't much of a restriction at all. Then have the dual vent and probably a baffle for zero effort.

Like I said, I've done it on hooped out old B230Fts that practically run on their own blowby. Works, helps keep the blowby/oil consumption in check, keeps them from blowing tons of oil out the seals, doesn't require doing anything drastic or reinventing the wheel, just a Y and a sharp 90 degree bend oil resistant hose off the oil cap itself (found a hose that would work).
 
Thanks for the info. So you don't think there's any point trying to fit a baffle inside the valve cover and using my existing setup?
 
Thanks for the info. So you don't think there's any point trying to fit a baffle inside the valve cover and using my existing setup?

You can just add (weld) a aluminum plate inside the valve cover directly over the opening - you just have to allow the vapor to escape, which it will. if there is a gap on either side. The plate will act as a barrier for (most of) the oil droplets in the vapor. Just make sure the cam lobes do not hit it.

pics of mine won't really help, it's a whiteblock setup with dual vents. The plate inside is just a piece of arched aluminum cut from a section of IC piping, and tacked in place

1508623_10151904681056370_2144950292_n_zps35176878.jpg


I'd do that, since you already have everything else in place.
 
That sounds like a plan to me.

I was thinking a short piece of aluminium tube with a piece of aluminium sheet welded over the end, and holes drilled in the sides.

Would it also be worth using some sort of foam or steel wool in there as an additional barrier for oil droplets?
 
That sounds like a plan to me.

I was thinking a short piece of aluminium tube with a piece of aluminium sheet welded over the end, and holes drilled in the sides.

Would it also be worth using some sort of foam or steel wool in there as an additional barrier for oil droplets?

Just an arched piece of aluminum stock, to prevent the oil being thrown/drawn directly out the vent, don't get any more elaborate than that.
 
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