Rb26 Blowing Oil In Catchcan

[Beer Baron]

yeah I agree, you need 1.1mm restrictor. envy have found the same thing. with their big engines with good oil pumps they still get too much up to the head so have started making their own 1.1mm restrictors. boostdr is on the right track. 1.1mm orifice, and lower the oil pressure. at least if you have an MLS head gasket you should be right to re-use it.

[Mark-32]

Thanks for the info. Scavenger pumps and one way valves just seem like the pump must be working too hard.

So how much oil pressure should i be aiming to run to keep the engine alive?

If the pump is running extremely high oil pressure I may be able to fix the problem whilst leaving the engine in the car, just removing the sump and not the head?

It all just seems weird to me as today I spoke to 2 different people who both run nitto pumps, they both even left the spring in when fitting there pumps had the exact same problems as me. They then removed the spring to lower the oil pressure and now they dont get any oil in the catchcan at all and thats with the 1.5mm restrictor in place. Neither of them have an external oil drain or inlarged oil returns either

Also, Can i re-use a metal layer head gasket a second time around? This will be the second time lifting the head since the rebuild using the same 1.2 nitto head gasket?

Cars and bloody money

[T04GTR]

just for arguments sake. we have a 32 at work. with a nice big fabricated sump. it had a breather can and from the breather can it drains to the sump via a -10 hose. this drain is on the drivers side. at high rpm it actually pumps oil up the hose and all over the engine... lol. so it would seem the windage from the crank is pumping the oil up the hose..

the nismo setup is good. having that in conjunction with a big 2-3L catch can with a -6 drain back to the passenger side of the sump should do the trick. well it did on a r34gtr that have a really nice arc catch tank that filled up every session at wakie. put the nismo seperator on with the outlet going to the arc. not a drop in it at the next outing.

[DVS JEZ]

you have to remember that enlarging the oil galleries and the oil return from the back of the head are great for letting oil back down but also let crankcase pressure up to the head.

[XRATED]

Try running a decent size breather line from the intake side of the sump (above the oil level) into your catch can... this will bleed off excess pressure in the crank case. Also, either take off your head 'drain' or plumb it into the exhaust side of the sump, otherwise it will be adding to your problem- not fixing it.

J.

[Beer Baron]

Thanks for the info. Scavenger pumps and one way valves just seem like the pump must be working too hard.

So how much oil pressure should i be aiming to run to keep the engine alive?

If the pump is running extremely high oil pressure I may be able to fix the problem whilst leaving the engine in the car, just removing the sump and not the head?

It all just seems weird to me as today I spoke to 2 different people who both run nitto pumps, they both even left the spring in when fitting there pumps had the exact same problems as me. They then removed the spring to lower the oil pressure and now they dont get any oil in the catchcan at all and thats with the 1.5mm restrictor in place. Neither of them have an external oil drain or inlarged oil returns either

Also, Can i re-use a metal layer head gasket a second time around? This will be the second time lifting the head since the rebuild using the same 1.2 nitto head gasket?

Cars and bloody money

yeah the MLS should be ok to re-use. 3 times is getting there but they have bugger all "crush" in them even from new so it could be fine. just do a visual inspection to make sure it's not damaged or blown anywhere and whack it in. some people reccomend a light coating of hylomar when re-fitting others will say never use hylomar on a MLS gasket. up to you. just make sure you check the head torque after a couple of heat cycles.

RB26 oil system set-up including crankcase ventilation is a pretty divided topic. everyone seems to have different ideas on what works. makes it hard for the average bloke to hit the right set-up straight away.

[Mark-32]

yeah the MLS should be ok to re-use. 3 times is getting there but they have bugger all "crush" in them even from new so it could be fine. just do a visual inspection to make sure it's not damaged or blown anywhere and whack it in. some people reccomend a light coating of hylomar when re-fitting others will say never use hylomar on a MLS gasket. up to you. just make sure you check the head torque after a couple of heat cycles.

RB26 oil system set-up including crankcase ventilation is a pretty divided topic. everyone seems to have different ideas on what works. makes it hard for the average bloke to hit the right set-up straight away.

Thanks for your help mate.

First things first i will put an oil pressure gauge on the car and do a leak down test for good measure.

[Mark-32]

yeah I agree, you need 1.1mm restrictor. envy have found the same thing. with their big engines with good oil pumps they still get too much up to the head so have started making their own 1.1mm restrictors. boostdr is on the right track. 1.1mm orifice, and lower the oil pressure. at least if you have an MLS head gasket you should be right to re-use it.

Made a few calls today, first off I spoke to Jim at Croydon as they were the guys who supplied me the engine hardware.

They said that its normal for the engine to be blowing oil into the catch can and I just need to fit a proper catch can with return line into the sump. He said If i fit a smaller restrictor it will make bugger all difference to the amount of oil entering the head. I reckon thats bullshit!!

I then rang envy here in sydney and told them about my setup and as Beer Baron said they certainly know there stuff. They said that its strange im having these issues at only 7800rpm and that they are using 0.9mm retrictors on there engines and are now even going to 0.7mm restrictor.

All in all this is a huge headf@ck

[BoostdR]

Made a few calls today, first off I spoke to Jim at Croydon as they were the guys who supplied me the engine hardware.

They said that its normal for the engine to be blowing oil into the catch can and I just need to fit a proper catch can with return line into the sump. He said If i fit a smaller restrictor it will make bugger all difference to the amount of oil entering the head. I reckon thats bullshit!!

I then rang envy here in sydney and told them about my setup and as Beer Baron said they certainly know there stuff. They said that its strange im having these issues at only 7800rpm and that they are using 0.9mm retrictors on there engines and are now even going to 0.7mm restrictor.

All in all this is a huge headf@ck

Going from a 1.5mm to a 1.1mm restrictor reduces flow by 47%. I have also dropped pressure. I'm sure it will make an impact.

Matt

[Mark-32]

Going from a 1.5mm to a 1.1mm restrictor reduces flow by 47%. I have also dropped pressure. I'm sure it will make an impact.

Matt

How did you drop pressure though?

Im hearing what you saying but I really dont want go ahead and lift the head and fit the 1.1 restrictor only to find I still have oil in the catch can once its up and going.

In saying that though i also dont want to fit the 0.9 restricctor to find im starving my top end of oil, especialy seeing that I have removed the spring fromm the oil pump.

The guys at envy spin their engines to 10,000rpm, dont remove the spring from the nitto pumps and have zero oil in the catch can with the 1.1 restrictor in place.

That makes me think maybe I should refit the spring in the pump and run the 0.9 restrictor?

Jim at croydon said that I shoudnt have removed the spring from the pump either and that the 26 engines need every bit of the 125psi oil pressure that the pump provides.

I dont want to drag this on but I also want to get it right so I can wind the boost up on the bloody thing and drive it.

[XRATED]

If I was you, I would listen very carefully to what Jim at Croyden has to say...

There is more than just one factor to your problem:

- Windage/Pressure build up in the crank case

- Lack of crossover hose from one cover to the other

- Draining

- Rocker cover baffles

- Catch can design

- Pressurised oil flow (not pressure) total

- Modification from factory design

When the GTR was first released, there was no such problem with pumping massive amounts of oil out the rocker covers... Somthing to think abaout?

My next oil/breather set up is going to include:

- 1.5mm oil restricters

- Trust sump extension

- Nitto pump and collar

- Matched and enlarged oil returns

- Multiple drain points from the rocker covers

- -12 hoses from the rocker covers to eachother (as factory... there is a cross over hose!) and to a catch can

- Baffled catch can

- Oil air seperator filters

- Lines back into the intake pipes (for negative pressure) after the AFM's

- Drains to the exhaust side of the sump (above oil level)

- -10 hose from the intake side of the sump (above oil level)

- -8 hose from the back of the head to the exhaust side of the sump

I will be pumping as much oil volume and pressure around as I can, if it's too much oil being pumped up then I'll create better ways to drain it back to the sump (4 stage scavenge pump), not restrict the flow too much. I think alot of the issues rb's have is the crossover hose from rocker covers are removed, thus not letting the pressure equalise between drain galleries/crank case either side of the crank (think windage). Any drains must run to the exhaust side of the sump as the intake side will become pressurised at high rpm.

Hope that helps.

Justin

[BoostdR]

If I was you, I would listen very carefully to what Jim at Croyden has to say...

There is more than just one factor to your problem:

- Windage/Pressure build up in the crank case

- Lack of crossover hose from one cover to the other

- Draining

- Rocker cover baffles

- Catch can design

- Pressurised oil flow (not pressure) total

- Modification from factory design

When the GTR was first released, there was no such problem with pumping massive amounts of oil out the rocker covers... Somthing to think abaout?

My next oil/breather set up is going to include:

- 1.5mm oil restricters

- Trust sump extension

- Nitto pump and collar

- Matched and enlarged oil returns

- Multiple drain points from the rocker covers

- -12 hoses from the rocker covers to eachother (as factory... there is a cross over hose!) and to a catch can

- Baffled catch can

- Oil air seperator filters

- Lines back into the intake pipes (for negative pressure) after the AFM's

- Drains to the exhaust side of the sump (above oil level)

- -10 hose from the intake side of the sump (above oil level)

- -8 hose from the back of the head to the exhaust side of the sump

I will be pumping as much oil volume and pressure around as I can, if it's too much oil being pumped up then I'll create better ways to drain it back to the sump (4 stage scavenge pump), not restrict the flow too much. I think alot of the issues rb's have is the crossover hose from rocker covers are removed, thus not letting the pressure equalise between drain galleries/crank case either side of the crank (think windage). Any drains must run to the exhaust side of the sump as the intake side will become pressurised at high rpm.

Hope that helps.

Justin

I'm going to have to disagree on a few of your points Justin, sorry mate

The factory car had no issue's as the pump pressure was matched to the factory restrictor. Cast piston clearance and ring gap is also much less than forged meaning less blow by. CRD'd comment about putting in a smaller restrictor making no difference intriges me as its not the first time I have heard a comment from someone there that is obviously incorrect. I think the story changes with who you talk to there.

So the issue shows itself because:

1. a higher pressure pumps flows more oil through the same size restrictor giving more in the head

2. more blow by from larger piston to bore clearance, which floats the oil in the head

3. G forces from track work and constant rpm compound the problem

So with what we know, reducing oil flow back to the std amount will not bring us back to factory spec due to the increased blow by gas. To get around this we need to do at least one of the following:

1. Increase drain back to the sump by enlarging the oil galleries which is not easy and not much diameter increase to be had

2. Run a crank case breather which will reduce the pressure differential from sump to head encouraging the oil to return

3. Install a rear head drain which also acts as a breather

As Sydneykid said a while back there is a multistep approach required to fix this issue. And you have to complete all the steps.

There are easier ways to get around the issue, however usually have a downside.

-Running a scavenger pump or catch can drain will still give a head full of oil which leaves less in the sump and a harder path for the blowby gas to travel up and out...usually resulting in a spun bearing or spitting the dipstick out.

Matt

[XRATED]

I'm going to have to disagree on a few of your points Justin, sorry mate

The factory car had no issue's as the pump pressure was matched to the factory restrictor. Cast piston clearance and ring gap is also much less than forged meaning less blow by. CRD'd comment about putting in a smaller restrictor making no difference intriges me as its not the first time I have heard a comment from someone there that is obviously incorrect. I think the story changes with who you talk to there.

So the issue shows itself because:

1. a higher pressure pumps flows more oil through the same size restrictor giving more in the head

2. more blow by from larger piston to bore clearance, which floats the oil in the head

3. G forces from track work and constant rpm compound the problem

So with what we know, reducing oil flow back to the std amount will not bring us back to factory spec due to the increased blow by gas. To get around this we need to do at least one of the following:

1. Increase drain back to the sump by enlarging the oil galleries which is not easy and not much diameter increase to be had

2. Run a crank case breather which will reduce the pressure differential from sump to head encouraging the oil to return

3. Install a rear head drain which also acts as a breather

As Sydneykid said a while back there is a multistep approach required to fix this issue. And you have to complete all the steps.

There are easier ways to get around the issue, however usually have a downside.

-Running a scavenger pump or catch can drain will still give a head full of oil which leaves less in the sump and a harder path for the blowby gas to travel up and out...usually resulting in a spun bearing or spitting the dipstick out.

Matt

Ha ha, you don't have to apologise...

We're pretty much on the same page though.

The piston/ring clearance difference isn't huge between a tightly built forged engine and a stock engine... plus there are plenty of stock piston/gap rb26's showing the same symptoms. I do agree there will be more blow by/combustion pressure getting into the crank case with forged pistons... but there are also many forged piston rb26's out there that don't show these symptoms.

When I was commenting on Jim's advice, I was reffering to replacing the spring in the oil pump... (Jim has ALOT of experience with 26's)- not oil restricters advice. I will be installing restricters, but no where near .9mm ...

A belt driven scavenger pump will get oil back into the sump ALOT quicker than gravity will...

[Mark-32]

Ha ha, you don't have to apologise...

We're pretty much on the same page though.

The piston/ring clearance difference isn't huge between a tightly built forged engine and a stock engine... plus there are plenty of stock piston/gap rb26's showing the same symptoms. I do agree there will be more blow by/combustion pressure getting into the crank case with forged pistons... but there are also many forged piston rb26's out there that don't show these symptoms.

When I was commenting on Jim's advice, I was reffering to replacing the spring in the oil pump... (Jim has ALOT of experience with 26's)- not oil restricters advice. I will be installing restricters, but no where near .9mm ...

A belt driven scavenger pump will get oil back into the sump ALOT quicker than gravity will...

Thanks for all the info that was very helpful. It gives me a couple of things to try help fix the problem before I go ahead and remove the engine from the car.

Two things I will try are the crossovver pipe between the rocker covers, and also swapping my rear head drain from the drivers side of the sump into the rear turbo oil return pipe that goes into the block. That way I can use the fitting that goes into the driverside of the sump as a breather that runs to a baffled catch can

Surely If you get to the point of having to use scaverger pumps to return oil to the sump then the wrong size restrictor is being used, either that or you have way too much oil pressure?

I mean you mentioned only running the 1.5 restrictor with the nitto pump, I realise that you also stated all the other oil return mods to but if im having these problems with the 1.5 restrictor and no spring in the nitto pump surely your going to be worse?

I just dont see how its healthy to have that amount of oil in the head for any preiod of time even if there is still enough in the sump to keep the bearings alive, especialy when the head gets that full to the top of the rocker covers to the point that it overflows out the rocker covers by the litre.

The smokey exhaust surely cant be a good thing either?

As I said before I would really like to avoid pulling the head off the engine again if possible as it means removing the entire engine from the car. I surpose Im hoping that someone tells me that amount of oil in the head is fine, dont worry about the smokey exhaust, just fit the nismo seperator and another catchcan with the drain to the sump and drive it.

I know that setup is far from ideal but surely if people are resorting to scavenge pumps and things then my setup would still work fine until I get around to lifting the head and replacing the restrictor? The car will not see any WOT for long periods of time, only short runs drifting and when on the dyno adding boost.

[BoostdR]

pull the head.

Skirting around the issue is just wasting time and possibly risking a motor.

I procrastinated for 12 months trying everything and eventually realised pulling the head was what had to be done.

[Mark-32]

pull the head.

Skirting around the issue is just wasting time and possibly risking a motor.

I procrastinated for 12 months trying everything and eventually realised pulling the head was what had to be done.

Yeah thats what I thought.

So lift the head fitt the 1.1mm and go from there!

Thanks for the input.

[XRATED]

Thanks for all the info that was very helpful. It gives me a couple of things to try help fix the problem before I go ahead and remove the engine from the car.

Two things I will try are the crossovver pipe between the rocker covers, and also swapping my rear head drain from the drivers side of the sump into the rear turbo oil return pipe that goes into the block. That way I can use the fitting that goes into the driverside of the sump as a breather that runs to a baffled catch can

Surely If you get to the point of having to use scaverger pumps to return oil to the sump then the wrong size restrictor is being used, either that or you have way too much oil pressure?

I mean you mentioned only running the 1.5 restrictor with the nitto pump, I realise that you also stated all the other oil return mods to but if im having these problems with the 1.5 restrictor and no spring in the nitto pump surely your going to be worse?

I just dont see how its healthy to have that amount of oil in the head for any preiod of time even if there is still enough in the sump to keep the bearings alive, especialy when the head gets that full to the top of the rocker covers to the point that it overflows out the rocker covers by the litre.

The smokey exhaust surely cant be a good thing either?

As I said before I would really like to avoid pulling the head off the engine again if possible as it means removing the entire engine from the car. I surpose Im hoping that someone tells me that amount of oil in the head is fine, dont worry about the smokey exhaust, just fit the nismo seperator and another catchcan with the drain to the sump and drive it.

I know that setup is far from ideal but surely if people are resorting to scavenge pumps and things then my setup would still work fine until I get around to lifting the head and replacing the restrictor? The car will not see any WOT for long periods of time, only short runs drifting and when on the dyno adding boost.

There are other reasons to run a multistage scavenge pump other than just oil return.. But I would much rather have alot more oil going roundy roundy than 'just enough'. There are other factors that affect oil pressure and volume other than the pump it self.. If I can't get the oil in the head under controll with 1.5mm restricters (I believe I can) then I will look at smaller or other options (there are other options other than restricers). I havn't seen a scavenge (only) pump on a 26 yet... I have used them on other engines though.

I would try swapping the head drain to the other side, add a cross over hose between the rocker covers and a decent size catch can with a drain before you pull the engine again... Your going to do it anyway, so what do you have to loose? If you test it properly, your not going to loose an engine..

Must be frustrating...

J.

[rob82]

This might seem like a dumb question but what is the need for a higer flow pump? Has anybody done any calcs on rod bearing forces? Surely if you have a set pressure that is "required" not to spin bearings then obviously you just need a pump that gets to the relief pressure by somewhere before peak torque. Engine oil pressure is just a resistance to flow so if an enigne reaches the releif valve pressure by say 4000rpm whats the point of a higher flow pump given that there is adequate oil temperature control.

What are the chances that the relief valve cannot bypass enough oil at high rpm and the pressure is going through the roof? Obviously when engines get built the bearing clearences are increased which means a higher flow pump is required to get to the same pressure at the same rpm.

[O2 Autosports]

Most people run high volume pumps because they're stronger and seem to suffer less failures.

I,ve been using an rb26 for drifting for the past four years and haven't had any trouble with oil in the catch can. Never tried a restricter bigger than 1.2mm and thats the only real difference be can see unlees you've got alot more blow by. I only have standard sump baffles also.

[Ziller]

You seem to be trying your best to solve this issue, you have had many theorys and solutions put forward to you that may or may not help but still no cigar as yet.

I can't help thinking that you might not have an oil presure or drainage problem but maybe a high crankcase pressure problem, you have a new built engine but don't take that for granted, if it hasn't got a good piston ring to bore seal or you could be chasing your tail.

I'm not saying that this is the case with you and I hope it isn't, is your engine builder helping you with this? I'm sure you paid him lots of money so he should be finishing off what he started in my mind.

Anyway good luck and I hope you find the answers in the end.