4agte pushing buckets of oil out of breathers (solutions?)

[~SlideWays~]

[Novel]

Hopefully someone has an answer to my problem, possibly someone who has raced 16v 4age's.

I have a smallport 16v 4agTe, and at the race track it pushes oil out of the breathers after a couple of hard laps. It only ever does it at the track, never on the road, even after a very hard drive. So it leads me to assume it is because of the constant high rev's (5000rpm to 7800rpm) at the track and high combustion chamber pressures?

My previous bigport 16v 4agte did the exact same thing. Toyota themselves tried to fix the problem on the smallport by adding the external oil drain. And that is one of the reasons I changed to a smallport.

But after swapping, it was the same old story, it would fill the catch can (used to have a 800ml one with a breather on top).

Compression test showed up fine, but it has always had quite a bit of blow by.

So I designed what I thought would be a solution, pretty much a bigger version of Toyota's external oil drain. Basically its a 2L catch can with twin air filters and a 5/8"drain from the bottom of the new catch can straight the sump. I even had raised box sections added to the top of cam covers for the new large breathers going to the catch can.

Here they are with the catch can:




Fast forward to today, I went to Manfeild to do some testing. I drove it hard for about 20minutes and it was going very well. Oil pressure looked good, water temp was fine (previously it had overheating issues after 5 laps). I was happy and gave a few people/cars a surprise!

BUT I pulled into the pits after a cool down lap and what do you know. A big oily mess, not a small amount either I'm talking lucky-there-were-no-dead-bearings amounts.

After a bit of discussion in the pits, it was decided to test blocking off one of the breather hoses (from factory there is only one anyway). Theory was that there were two from the cam covers but only one, of the same size draining to the sump. So I tried it, did 4 or 5 laps and its was a $&#$% mess again.

So...it didn't work.

I've had three different 4agze's (one supercharged smallport, one turbo bigport and one turbo smallport) and they have all had the same problem. The current one is the worst, and also the highest hp and gets driven the hardest.

There are plenty of reports of the problem all over the internet, Toyota's external oil drain is proof of the problem...but WHAT WILL FIX IT?

As far as I am aware, 20v's do not have this problem.

-----------------------

- Can the oil drain channels in the head and/or block be enlarged?
- What about restricting the oil flow to the head?
- Is the blow by contributing enough for such a large amount?
- Do I need to pull down the short block and check piston gaps/cracked ringlands etc? If I have the bottom end rebuilt, should I go for factory piston clearances or give it a bigger tolerance...which would cause blow by again. Will it actually help the issue with the head filling with oil at all?
- The catch can drain goes to below the sump oil level. Would this be enough to restrict it draining?
- Any other suggestions?


I am open to anything, I want to be able to drive it for a decent stint at the track and not have this issue. It looks like I've go the cooling and braking under control but it this damn oil/breather issue that's rearing its ugly head again.

Any suggestions or experiences would be appreciated.


Cheers

[QikStarlie]

up the diameter of breathers to start with. this is the only thing i did to mine and it made a big diffrence, single 1" pipe. thru baffled (keeping flow no less than 1") catch can and 1" exit, vented to atmo, no filter, they clog. bigger the breather less velocity to throw oil out.

run another drain in the back of the head lower down,

also those small filters wont be helping, soon as they get oil in them will be like a cork, so crank case pressure will rise. may find since you return is lower than the oil level crank case pressure is pushing oil back up the drain.


short version i would put fitting in the back of the head low down and plumb it straight into your sump. above oil level. plus add big free flow catch can setup.

edit: have you tried running it without the breather filters?

[Crucible]

It will be interesting to see what solution you come up with. I just put it down to the nature of the beast ie: Higher boost more blow by and crankcase pressure etc. My can setup like yours less drain, never worked that well either, lots of oil after giving it a hard time..

Always thought I should of baffled the can also prior to venting but thought the steel wool in the covers would of stopped oil reaching the breathers, all trial and error i suppose..

QuickStarlie has a few good suggestions.

[Vertigo]

definitely plumb the return ABOVE the sump oil level! thats a large part of the problem. make sure the return line is fairly large diameter, also.

[~SlideWays~]

up the diameter of breathers to start with. this is the only thing i did to mine and it made a big diffrence, single 1" pipe. thru baffled (keeping flow no less than 1") catch can and 1" exit, vented to atmo, no filter, they clog. bigger the breather less velocity to throw oil out.

run another drain in the back of the head lower down,

also those small filters wont be helping, soon as they get oil in them will be like a cork, so crank case pressure will rise. may find since you return is lower than the oil level crank case pressure is pushing oil back up the drain.


short version i would put fitting in the back of the head low down and plumb it straight into your sump. above oil level. plus add big free flow catch can setup.

edit: have you tried running it without the breather filters?

Cheers for the suggestions:

Each cam cover breather is 5/8" I/D hose so a total of 32mm of breathing capacity from the head (not including factory oil drain). This was a massive difference from the tiny factory single breather.

The air filters might look small but they are both 25mm outlets so a total of 50mm or 2" of breathing capacity from the catch can.

I think the oil draining to below the oil level (pretty sure, will have to measure) is definitely contributing. I'll look at move it up as high as possible.

Good idea with the secondary oil drains, do you mean the lowest point of the cam covers or tap into the head itself? I could easily add some big outlets below the current big breathers (about 5cm lower), and maybe have it drain to the sump but at the back/firewall side to get it out of the way.

[matt dunn]

do you know that a 50mm hose will flow about 4 time the amount of a 25mm hose.

So two 25mm hoses are still half the flow of a 50mm hose.

[~SlideWays~]

do you know that a 50mm hose will flow about 4 time the amount of a 25mm hose.

So two 25mm hoses are still half the flow of a 50mm hose.

Interesting point, would be quite hard to fit a 50mm diameter hose in there though.

Out of interest in your race car, have you always run a 20v head? If not, did you ever have head oil surge problems? Obviously north south on yours vs east west on mine, but I also had the supercharged smallport in an AE86 and that also had similar problems.

[allencr]

Pic of the baffle/s between the cam & outlet on each cam cover?
Thanks.

[~SlideWays~]

Pic of the baffle/s between the cam & outlet on each cam cover?
Thanks.

Don't have pics of the inside of those box sections, the guy that did it for me supplied the alloy etc. This was over 3 years ago (has been sitting for ages with mortgage blah blah), it'll just be a big hole drilled into the covers then a plate over the top with gaps to let the air through. Then covered over with the raised box sections. The idea with raising it was to stop oil surging out the breathers.

[Dell'Orto]

Solution - run no oil

Or dry sump *nod*

[saft]

running the return below the oil level means you may well have oil coming back up the line into the catchcan from crank case pressure

[CelicaGT8]

Loop the pipe

[crispy'86]

Have you tried running normal 4age cam covers with the baffles in them or are they removed ??

[DexGT]

I had a similar problem in the starlet , it would fill a 1 ltr catch bottle in not many runs at the track . I decided to build a better system and it ended up like this



I drilled all the fittings on the head to be the same size as the hose , inside the box it goes thru foam and any oil drains to the low point where it can go to the sump.

The thing I think actually does the most is in the cam cover , I removed the plate that's fitted factory for separating the oil ( which it doesn't) and used an idea I got from the problems RB26's seem to have (people remove the gauze stacks that are fitted factory, then get oil problems) I fitted a stack of gauze under each breather pipe and a goldilocks pad around the stack.
I have now done 2 manfield dual car sprint days and the catch box is barely damp inside.
Your welcome to come have a look if you want.

[matt dunn]

Out of interest in your race car, have you always run a 20v head? If not, did you ever have head oil surge problems? Obviously north south on yours vs east west on mine, but I also had the supercharged smallport in an AE86 and that also had similar problems.

It is a common thing with all 4age's, My 20V had the same problems.

I have it sorted now though.

You need to run a rerurn line into the sump,
must be above the oil line and not in a place where the crank pushed pressure up the hose, have tried a couple of places in the sump, the first did not work the second one did.

Also need to run a baffeled catch can with a reasonably large volume,
not just to hold the oil, but the large volume has a slower air speed through it so the oil drops out of the air,

I also changed from 2 15mm pipes to a single 40 mm one, welded into the tappet cover,

and I also run the oil level about 2 or 3 mm down from the full mark on the dipstick. If you fill it further it will just blow it all out back to this level.

That's all on my car anyway.

Last season it ran the 2 small breathers and no return to the sump,
and over a rtace weekend I would drain about 3 litres or more from the catch can, but it did turno out to have a mechanical issue too at that stage.

[QikStarlie]

^ this. if your cam cover breathers aren't baffled well, wont be helping much. didn't think about that yesterday. from memory on mine, i removed the plate in the cam cover drilled it out so flowed more, re-attached. welded on the oversized breather in stock location.

my other car i just run 2 filler covers. so 2x standard breathers. no issues so far, hasn't been pushed as hard as the above though.


for oil drain, yeh i mean low down in the head itself. need to get drain low as possible, as you need to keep the oil level below the crank case breather gallery. (big one in middle of head on exhaust side) probably want to do as last resort since will be a pain in the ass to do.

re filters. was more suggesting once they are over oiled, they are super restrictive. try blow thru them

[CAMB01]

Its not just Toyota's that have this problem. My EVO does the same thing at manfeild. I'm filling the catch can up after 2 laps. Makes one hell of a mess in the engine bay after every run, even get oil spraying onto the windscreen from the small bonnet vent on the right hand side. I have the breathers baffled inside the catch can but the oil sill makes its way out. I have a drain going into the side of the block well above the oil level.
The catch can wont drain while there is pressure in the crankcase.

I dont have any problems doing street sprints though, and im revving higher also. On the track i dont rev over 7200rpm, but doing street sprints im revving between 7500 and 7800rpm.

I may have to come see you webster about catch internal deisgns.

[~SlideWays~]

Bugger so its not just a 16v 4age problem then...

RB's and 4g63's... must cause a lot of run bearings!

Cam, sounds like you're in the same boat too. Its pretty crap thinking about all that oil leaving the block while pushing it around the hair pins

I'm going to do the following:
- Enlarge the drain diameter from catch can.
- Raise drain inlet into sump
- Add two more outlets in cam covers at the lowest point, draining to the sump as well.

So hopefully that should mean that when oil surges in the head it SHOULD mostly drain into the lower cam cover outlets first, while crank pressure is relieved through the two higher cam cover outlets going to the catch can.
This will also let the block breath through both sump drain hoses and the factory external drain.


In theory...

[Vertigo]

also try adding a flap at the oil return inlet, not sure how effective it would be, but might help stop oil sloshing up the pipe around corners and causing more issues. definitely needs to be above oil level if at all possible tho.

[Adoom]

Are those dish washing sponges?