Crankcase pressurisation and breathing on a turbo motor

[sowen]

On my Rover P6 with a later Rover M16 twincam n/a lump and turbo I've got issues with the crankcase pressurising and throwing oil out of the breathers and white smoke out of the exhaust. I've tried copying a schematic of a Nissan SR20 which has the rocker breather piped via a one-way pcv valve to the inlet manifold after the throttle, and the crankcase attached to a canister/seperator the piped into the intake between the air filter and turbo. I still get some impressive clouds of smoke out the back usually when it warms up and given full throttle. Last night I re-checked the pipe from the seperator to the intake and that was clean, no oil. There was a little oil in the hose from the rocker cover to the pcv valve.

Any ideas/suggestions?

[froggy]

I tried to get the factory breather system to work on my Saab engine when I fitted a much bigger turbo and went with a 1.5 litre catch tank with a 25mm ext breather filter to sort it

[Deleted]

I had similar symptoms years ago with a 2l 16v golf motor, big turbo, in a golf 1 pickup. Tried all sorts of things, breather wise and got nowhere. Turned out to be the oil drain from the turbo. Make sure it is as direct as possible. As big a diameter as possible. And most importantly that it definitely enters the sump above the oil level. I landed up fitting a much bigger drain and sump. Not a wisp of smoke after that in the three years I had it as a daily.

[sowen]

I've had a little break and have a slightly clearer mind now!

Forgot to add the engine oil pressure is around 60psi, I suspect this could be a major contributing factor?

Oil drain is 1" diameter and as near straight as straight can get. The fitting into the sump is a 30mm elbow, and sits above the oil level.

I'm also wondering if in my experimentation I've managed to fill the bottom of the intercooler with some oil, and when it warms up it's sucking it through? I had it off recently and drained a little out, but since changing the turbo the intake pre-intercooler is perfectly dry.

Maybe I should try a large catch tank? I had one of those little ones and it used to fill up with milky water, so I'd really want some form of seperator that naturally drains back into the sump.

Maybe a wing off the side of the sump below oil level that would let unpressurised oil drain back down from a large seperator/catch tank without crankcase pressure blowing it back up could work?

[ChasR]

Here is my breather experience.

On my RST it is as follows:

-An outlet in the crankcase
-A turbo drain inlet on the sump
-Two outlets on the rocker cover.
-One small inlet on the inlet manifold with a 1 way valve

As standard it went as follows:

-Turbo drain went to the sump
-Crankcase outlet went to the one of the rocker cover connections
-The final rocker connection went into an emmisions valve of sorts, which would either put the crankcase gasses back into the inlet manifold or back into the inlet on boost. It worked very similar to the carbed systems as below:



However, this setup is deemed iffy if you go to a ZVH (like me) since the setup breathes more crankcase gasses or modified engines). Mine had the following after this:
-A pipe going from the crankcase to the rocker cover as standard
-A pipe going from the rocker cover to a catch can with a filter on it.

This worked but I did notice some parts of the engine misting slightly and the oil fumes getting on the engine and cambelt which were next to it.

I could have left it as above but if you can avoid the smell of oil and it putting stuff over the engine why not take that choice? I now have a Bailey breather separator which is as the following:

-Crankcase outlet now goes to the bottom of the tank
-Both rocker connections go in tangentally to the centre of the tank
-A final bottom outlet of the breather tank either breathes to atmosphere or is plumbed back into the inlet.
-Inlet manifold is blocked unless you go for a Spec-R separator and retain the 1 way valve.

With this the engine has stopped misting from the seals ; for the first time to the sump is dry all round. However, since I went from a boggo standard 5W30 to a Millers 5W40 it now mists from near the tank slightly in the form of smoke, with no residue left. I think one of the pipes is a little iffy, something which I plan to sort in the future.

AFAIK the Porsche 944 Turbo setup is very similar to the Bailey tank setup even down to the tangental connections IIRC.

[sowen]

So you have something like this ChasR ?



This is the schematic I've based my breather system on:



The difference with my Rover engine to the Nissan engine is it has two 3/4" ports on the crankcase for breathers, one either side. Both of these are piped into a small catch tank which has a small 10mm pipe going to the intake pre-turbo. Before I piped it into the intake it blew oil all over the inner wing, but since putting the pipe on hasn't obviously had any significant oil flow through it. On the other side I have a single port off one rocker cover through a Saab pcv valve then through a brake servo one way valve. I haven't taken the inlet manifold off recently to see how much oil is inside there, that's a job for later.

What I could do is fit another pipe from the second rocker cover as in the Nissan schematic and route that into the seperator aswell? Also, make a new seperator/catch tank that mimics the Bailey tank (budget is tight and I have metal) and try again?

[squonk]

The M16 is basically the same as a T16 but without the turbo. It is designed to run at much lower pMax pressures than the T16. The T16 itself has a reputation for blowing head gaskets so boosting an M16 above what it was designed to take may well be forcing combustion pressure past the head gasket into the oil ways and pressurising the sump via the drain from the cylinder head. The white smoke from the exhaust suggests that water is getting into the combustion chambers too, all pointing towards either a cracked head or head gasket issue. If it were forcing oil into the combustion chamber that had collected in the intercooler the smoke would be blue.

If you have blown the head gasket make sure you replace it with a genuine Klinger gasket as these are recognised to be the best available for this engine (or at least the T16 version).

[ChasR]

Pretty much :

[sowen]

Aug 16, 2015 17:30:42 GMT squonk said:

The M16 is basically the same as a T16 but without the turbo. It is designed to run at much lower pMax pressures than the T16. The T16 itself has a reputation for blowing head gaskets so boosting an M16 above what it was designed to take may well be forcing combustion pressure past the head gasket into the oil ways and pressurising the sump via the drain from the cylinder head. The white smoke from the exhaust suggests that water is getting into the combustion chambers too, all pointing towards either a cracked head or head gasket issue. If it were forcing oil into the combustion chamber that had collected in the intercooler the smoke would be blue.

If you have blown the head gasket make sure you replace it with a genuine Klinger gasket as these are recognised to be the best available for this engine (or at least the T16 version).

I'm certain it's oil, the water level in the header tank is stable. The smoke is mostly white, with a bit of blue, hard to tell in the small rear view mirrors. I'm sure I've read the original M16 Tickford turbo was far superior to the T16 factory turbo, only difference in my setup I believe are the pistons, so maybe it's time to fit a decompression plate and see if dropping the combustion chamber pressures helps reduce the issues?

[squonk]

The Tickford engine was somewhat different different from the stadard M16. It had lower compression cast (not forged) Mahle pistons, sodium filled valves, different rods and I believe the heads were wire ringed so it was a very strong engine. In standard form the M16 is little more than an O series with a sixteen valve head!! The T16 also used Mahle pistons, and had stronger valve springs, larger exhaust valves and different rods, different cams, different injectors and a better head gasket - in some ways it was better than the Tickford and in some ways it was worse.

When turboing a standard M16 and keeping the standard pistons it is generally considered that the compression ratio becomes too high causing a lot of problems. A common mod is to fit O series turbo pistons as they have a deeper bowl and reduce the compression slightly. They also fit on the M16 rods whereas the T16 pistons won't as the rods use a different pin size

[sowen]

So far the standard headgasket with ARP headstuds has been holding without issue on 10.2:1CR. From my research the O-series pistons require skimming the top edge off the pistons, the block machining down to match, and a head skim, even then the CR I believe is crazy low, 8:1 or something?

The reason I started this thread is I pressurised the crankcase and blew one of the camshaft seals out, dumping half the oil over the belts and sprayed it everywhere! As per the other suggestions I've started making a new seperator/catch can and will weld a new port in below oil level so that oil can drain back un-pressurised.

[The Jackeria]

I'm yet to read posts above, here is what my car does when it idles for over a minute or so above 85 degrees. Never at cold or from start up or boost and only when left idling for a while, I've got a new oil pressure sender coming. I'm wondering if it has something to do with the shallow sump I have and oil level, I just did a change and didn't really think about how much less oil I should put in because of the shallow sump, I just put in the recommended amount. As the drain is on the rear of the engine, to test my theory one day when I can, I'll sit the car on a downward facing slope (so the oil level is away from the drain) and see if it smokes then. If it does then I'll be doing compression tests and possible getting a new turbo =(

its a video, click it =D


I've got stuff for an oil catch can but haven't fitted it yet so could be a possibility.