Oil issue? 3.6 conversion

[safe]

I have recently (last monday) finished my RSR-ich build, only took me 5.5 years... Finished is a strong word, there is still a bunch of things to do.
Its a 1969 widebody car, g50 gearbox, 964 3.6 engine, coilovers and a bunch of modifications...
This weekend I took it to the track for the first time, 400 miles after rebuild of the engine.

So to the issue...
I started slow, got a feel for the car, increased speed, harder on the revs. After a session or two in a sharp right hander after the straight the car laid a thick* smoke screen about 50 yards long, then the same in another right hander a bit further down.
I didn't notice this at all but I got called in to the pits immediately and was greeted by the rescue team with fire extinguishers...
But luckily there was no fire, no leaks, nothing.

So I checked the intake and there was some oil in there, I figuered that oil was pushed into the intake from the tank. I cut the hose between the intake and oil tank, plug the hose to the intake, and put a makeshift catch tank on the short hose from the tank.
I checked the oil level in the tank, it was right between MIN and MAX, I remove 1.5 liters of oil because I remember I put in 11.5 liters when I changed my oil last time and you never need to replace more than 9-10 (911 SC oil tank).

With this done next day I go out do some slow careful laps, start to push harder and pretty soon I'm flat out. I go like this for several laps, then out of the blue at the same spot another smoke screen maybe not as large as the first time, I don't notice it, still pushing hard for a lap or two no more smoke, I go into the pits, check the catch tank and there is not a single drop of oil in there.

How can the engine put out a thick smoke screen of oil without it coming from the intake?

Sorry for this long text.

*By thick I mean it obscured buildings, made those behind me break and switch on emergency flashers...

[bpu699]

Were you engine braking?Accelerating? Or doing a high-g turn at the time? No turbo I assume?

Air filter not doused in oil?

When you mix and match motors and oil tanks, a normal oil level is tough to guess. The dipstick may be way off...

[silverc4s]

May be too thin oil on right turn getting sucked into valve guides...

[-Levi-]

subd,

how many oil coolers are you running and how much oil are you using?

[safe]

Originally Posted by bpu699

Were you engine braking?Accelerating? Or doing a high-g turn at the time? No turbo I assume?

Air filter not doused in oil?

When you mix and match motors and oil tanks, a normal oil level is tough to guess. The dipstick may be way off...

Engine braking during braking, then on slight throttle during a tight right hander downhill that immediately turns into a left hander over a crest. Somewhere in this combination the smoke came, I didn't see it myself.

No oil in the air filter, not more than there should be. Should have said that I have an after market cone filter pretty much directly on the intake. No airflow-meter or MAF (using MAP and TP with VEMS ECU).

I've been thinking of oil tanks and its location relative to the engine. Does it really matter when its a dry sump? The engine might be slightly lower in the tub than what an original engine would be.

[safe]

Originally Posted by silverc4s

May be too thin oil on right turn getting sucked into valve guides...

10w60 oil, but way to much smoke to come from a missing valve seal. Valve guides are new.

[safe]

Originally Posted by -Levi-

subd,

how many oil coolers are you running and how much oil are you using?

Just one Setrab in the front.
Total amount of oil, no idea.
As I stated after I emptied the engine and tank for an oilchange I added 11.5 liters (or quarts) to get middle of the dipstick which seems like a large amount of oil. Maybe the dipstick is for a different tank...

Before the oil change I had the car on a dyno for half a day with no smoke issue. I think it must be G-related and/or oil level related.

[Steve@Rennsport]

G-related, indeed!

I would revisit how the tank is mounted in the chassis. You will need a catch can, for certain.

[safe]

Originally Posted by Steve@Rennsport

G-related, indeed!

I would revisit how the tank is mounted in the chassis. You will need a catch can, for certain.

Catch can, check!

The tank is a stock SC tank in the original position. Is that suficient or is there some additional trickery I need?

[gduke2010]

I usually, only add 8-8.5 quarts when changing my oil and warm with the engine running, the oil is only 1/16 - 1/8 above the bottom mark on the dipstick. I have 2 oil coolers in series, the original cararra cooler and a front mounted Setrab. My car is a 1985 911 with a 1995 3.6.

[Sboxin]

.
.
You may still have had oil in the intake system from the first two smoke events.

We had this issue before adding a catch can back into the breather hose to the intake - in fact
there was a large amount of oil that drained into the #3 cylinder during a 2 month pause running the engine.

Also agree with only filling the oil tank 1/2" above the low oil mark on the dip stick - when the oil
temp is above 180F and the oil line thermostat has opened to circulate the oil to the front oil
coolers.

Our oil tank is the original 1978SC tank in original location.

Regards,

[safe]

Thanks guys! Good to have some data points on the oil level.

Yesterday I plugged the intake that went to the oil tank before more permanently (than duct tape) and I will build a catch can of something better than a flimsy PET water bottle...
Fitted the proper oil temp sender on the engine for my 69 instrument cluster. Hopefully it will now show the correct oil temp.
Also need to fit a proper oil pressure sender, because I'm not really sure about what pressure I'm seeing. Most of the time It's probably double (which I think is "right" for this combo) but sometimes it pegs at 10 bar and that's more than what is correct.

I'm gonna run a trackday in early september that I know have some high g right handers. Trial and error, see what happens. Maybe a trackday on a small track late august and an auto-x/slalom next weekend.

The car, but lacking the gold-stripes that I'm in the process of adding right now.

[-Levi-]

Keep us posted please

[safe]

Originally Posted by -Levi-

Keep us posted please

Mostly unresolved.
The car has been out of commission since early 2018 due to a transmission issue (leading to a rebuild), but its all together now.
The engine started last weekend for the first time since transmission had to come out.
It had developed fuel leaks (yes multiple) and possibly it had fuel starvation issue (I hope). So I changed out some fuel lines and installed a fuel surge tank in the smuggler compartment. That was really tight and didn't really fit, but I have no lid on it anyway.

Hopefully I can get it out on the streets in a few weeks and on to some track/auto-x runs later.

[-Levi-]

Any updates?

[safe]

Originally Posted by -Levi-

Any updates?

Sadly not. I got the car back on the road, got an MOT (the last for its life), drove it for 20 km then the clutch fork in the transmission failed. The pin that holds the clutch fork in the G50 worked free and one ear broke off in the transmission. So the trans is out again waiting for another welding repair...

[stownsen914]

Sorry to hear of the ongoing troubles. Before you head to the track again, make sure your intake is clear of oil, as someone suggested above. A prior overflow from the tank when you still had it plumbed to the intake could have left residual oil that a high G turn causes to make its way into the motor. That’ll smoke like a mother.

[safe]

Car is back together. Fitted a catch tank, filled oil tank to between min and max.

Did some high speed slalom driving yesterday and oil puked out in the engine bay.
I'm convinced its g-related, didn't puke out anything o the dyno recently.

I have a look at the catch tank, it was a really cheap chinesium thing, thought it would be better than a soda bottle, but a more careful look makes me think the soda bottle was better engineered....

So I'll be making my own, just from regular steel, exhaust pipe and scrap steel from the pile of junk.

On the other hand the fuel mods I've made seem to work, the gearbox and clutch are working.
So after buying and started building this car in september 2010, its nearing a usable state
Tires were made in september of 2009!!! They seem ok still, looking at them, but I hade a hard time getting heat into them.



A question to you, if I would like to drain the catch tank (in the back right corner of the engine bay, near the shock tower) back into the engine how would you do that?
I was thinking of making the drain 1 inch above the bottom of the catch tank, a relatively small line like 1/4 -3/8 inch straight down through the tin and jacking it into the S-line going to the engine. Bad idea?

[stownsen914]

Just to confirm how you have this plumbed … the breather from the engine is going to the tank, and the catch can is connected to the tank … correct?

Also, make sure your catch can has a way for air to escape (e.g. one of those little breather vent things, looks like a miniature air filter). Otherwise the vent will just blow itself off the catch can and distribute oil everywhere.

As for a drain, do whatever is convenient. Ideally you shouldn't be getting much oil in the catch can, but it is nice to have it easy to check and empty as needed.

[safe]

Originally Posted by stownsen914

Just to confirm how you have this plumbed … the breather from the engine is going to the tank, and the catch can is connected to the tank … correct?

Also, make sure your catch can has a way for air to escape (e.g. one of those little breather vent things, looks like a miniature air filter). Otherwise the vent will just blow itself off the catch can and distribute oil everywhere.

As for a drain, do whatever is convenient. Ideally you shouldn't be getting much oil in the catch can, but it is nice to have it easy to check and empty as needed.

Yes from engine to tank and from tank (filler neck) to catch can. The catch can has a tiny little "air filter".

After 8 runs of the 90-95 seconds lap (high speed slalom, avg speed of 65 mph, top speed 120ish) I had half a quart in the catch can and more in the engine compartment draining out on the ground.
I think that catch can was so bad it blew oil from the inlet right at the filter basically.

Yeah, ideally there would not be much oil in the can, but I think I would need more baffles in the oil tank to prevent that, or run lower oil level in the tank. Maybe I need to rethink the stock oil tank.