MESSY OIL LEAK on modified engine 911 2.2

POR71 · 10-12-2010, 10:16 PM

Hi,
First off all in my book an oil leak is always messy....

After some carefull examination it apparantely comes from the air filter housing...in the middle off the housing is small opening where the oil pours out over the top off the engine...
No leakge on carter ventillation, oil thermostat and oil pressure sender so that's good news....
Apparentely the oil is pressed through the oil reservoir breather tube into the air filter housing. At the back here the tube connects to the air filter housing there even is an oil trap mounted, but there still relatibvely lotts off oil coming through....
Checked the oil level on the dipstick at 80 ° at it's at max....could it be that the carter ventillation is pushing to much air and pressure into the oil reservoir and so pushes the oil through the breather?

Should there be a tube connected to the lowest point on the air filter housing, if so where does it dumps the oil into?

The car is a 911 1968 SWB....
The engine is a 2,2 E carter, 2,4/2,7 Crankshaft, 2,2 T-Type pistons/cylinders and valve train....
The carter had an OIL BYPASS, 1989 Carerra oil pump and hydraulic chain tensioners fitted....also on top of the cylinder heads where the oil line enters on either side of the heads there is a smaller nipple fitted thus allowing more oil pressure.....
Could it has someting to do with all the modifications to the oil flow and pressures in the engine?
Anny suggestions on how to rectify...?
The engine runs perefectely, good compression and good torque.....
Thks

silverc4s · silverc4s's Garage

Hello, trying to understand your situation, and have a couple of questions... First not sure what you are referring to as a "carter" could that be the two 3 venturi carburetors on the engine? They will be either Weber, Zenith, or Solex by brand and have a large black steel air cleaner housing joining both of them above the engine.

Is that air cleaner housing where the oil is coming from?? If so, you have likely gotten too much oil in the wet sump system, and will need to rectify that.

Does the engine have an external oil cooler in the front wheel well? If not, it will be fairly simple to drain the oil & refill with the proper amount.

It is best to set the level on the dipstick with a warmed up engine; running on level ground; about midway between the marks. Possibly a little higher, but overfilling will always result in what you have right now.

Good luck, post some pictures of your car & let us know how things proceed.

1QuickS · 10-13-2010, 07:14 AM

I expect the issue to be oil vapor from the oil tank collecting in the air cleaner. Your air cleaner has a little tube that is on the bottom surface toward the firewall end of the housing. There should be a rubber tube that drains the oil from the air cleaner housing and directs it to a drain pipe assembly that is attached to the forward side of the passenger side engine shroud (forward of the oil cooler) and lets this oil drain outside the engine compartment. Remember that the air cleaner housing is a low pressure area so it cannot deliver high pressure air to your oil tank.

POR71 · 10-13-2010, 10:47 AM

Euh, "Carter" is the engine block
No external oil cooler at the front
Yes, it's the air cleaner housing where the oil pours out at the bottom,
There isn't a tube connected so all the oil is swept over the top of the engine...

I thought that the engine block breather on top of the block (middle near the thermostat and oil pressure contact) was pushing too much air in the oil tank through the black tube, look at the picture:

And this is the tube which directs the oil to the air filter housing

And this is the bottom of the housing where the oil pour out

YOU SAY
"""It is best to set the level on the dipstick with a warmed up engine; running on level ground; about midway between the marks. Possibly a little higher,"""

Why did they put MAX on the dipstick that high then???? Isn't Haynes telling to read oil level on the dipstick at warm engine 80 °C*176°F, so you supose you could go to maximum at that temp, it will even go to +/-120 °C so that's probably why the oil expands even further and blows out through the filter housing...
Can I adjust the thermostat whit the little screw on topallowing it to open faster and cool the engine more?
THKS

silverc4s · silverc4s's Garage

Quote:

Originally Posted by POR71

Euh, "Carter" is the engine block
No external oil cooler at the front
Yes, it's the air cleaner housing where the oil pours out at the bottom,
There isn't a tube connected so all the oil is swept over the top of the engine...

I thought that the engine block breather on top of the block (middle near the thermostat and oil pressure contact) was pushing too much air in the oil tank through the black tube, look at the picture:

And this is the tube which directs the oil to the air filter housing

And this is the bottom of the housing where the oil pour out

YOU SAY
"""It is best to set the level on the dipstick with a warmed up engine; running on level ground; about midway between the marks. Possibly a little higher,"""

Why did they put MAX on the dipstick that high then???? Isn't Haynes telling to read oil level on the dipstick at warm engine 80 °C*176°F, so you supose you could go to maximum at that temp, it will even go to +/-120 °C so that's probably why the oil expands even further and blows out through the filter housing...
Can I adjust the thermostat whit the little screw on topallowing it to open faster and cool the engine more?
THKS

There should be a tube connected to that air cleaner - I seem to recall that it goes to the thermostat on the top of the engine. The hose from the filler neck is also going to the air cleaner, just to suck up & burn any oil fumes - no actual oil should travel that path, or very very little, at any rate.

The marks on the dipstick are there to be an assist to the owner in managing safe oil level. You will have to get to know what range is safe in your engine, based on oil temps, etc. I think that there is about 1 quart or even less between the min and max marks on my cars, so at the top end it is easy to overfill if not careful.

There is no adjustment of the thermostat that I am aware of.

POR71 · 10-13-2010, 11:47 AM

Hi,
Think I 'll adjust the thermostat then (see underneath) and drain or suck out some oil out the oil tank.....so the dipstick reads a bit lower (as you state) then start the engine and disconnect the black tube from the air cleaner housing tot the oil tank and see if it still pushes out the oil this way and maybe further adjust the oil level this way......keep you posted THKS!!!

Just found you can adjust the thermostat with the little screw....

"""The set screw in used to adjust the opening of the thermostat. As the screw is turned in, it lowers the oil temp at which the thermostat is completely open. You can find the plastic washer at any hardware store."""

POR71 · 10-13-2010, 12:16 PM

Hi,
Anyone experience in these adjustable thermostats? Think the same type is just in all the early engines? I could srew mine in about 0,7 cm how does that correlate to how many °C or °F temperature reduction?
Thks

cjmurph · cjmurph's Garage

POR
I don't have any advice on the thermostat but, I believe my 2.2 was stock. It had a small drain line that went from the bottom of the housing through a small opening front of the motor and actually had a "catch" for excess oil mounted near the cooler.
I'll try and grab a pic.
Curt

mskala · 10-13-2010, 07:13 PM

First of all, with google helping with the search, I found this link: Setting adjustable oil thermostat? .

You would need to pull the thermostat and test in water or oil bath with a good
thermometer to really set it, if that screw really works (I have not touched mine).

But, also I believe it is completely irrelevant to your oil leak problem. It's vapors
rather than high level splashing out, so get all the hoses correct.

1QuickS · 10:14 AM

There is an oil cooler on the right front of the engine and the little tube on the bottom of the air cleaner runs to this breather which is attached outside the engine shroud, forward of the oil cooler on the right front of the engine. The grey fiberglass shroud that runs diagonally across the top of your engine ducts cooling air to the oil cooler I describe. If you look to the right of the pressure oil sender in the engine shroud, just below the rubber seal you should see the hole for the breather tube to stick through availing your rubber hose to attach to it, at least that is how it was done for the O and A series 911s, if your engine and shroud is a later version then this oil drain may have been achieved differently but your air cleaner does have a simple drain spigot.

POR71 · 10-14-2010, 10:31 AM

Hi,
The engine runs now at 105 °C (Thanks to adjusting the oil thermostat). So cooler then it was and sucked out the oil till it was underneath max....it cured the problem....still no tube on the underside of the air cleaner housing but don't think it 'll be that urgent anymore...winterproject maybe...
Anyway THANKS TO ALL for the great comments and info....keep it up...

mskala · 10-14-2010, 11:58 AM

I had an old style but non-working thermostat, so I took the adjustment screw out,
put a bolt in, and saw what the adjustment does. Clockwise moves the mechanism
downward. Before the limit of adjustment, it will start to open the port to the oil
cooler.

You do not want to adjust this screw with the thermostat in the car, as opening the
port to the cooler at room temperature is going to allow cold oil at the highest
pressure to the cooler, which is one thing the thermostat is there to prevent. Keeps
the oil cooler from being damaged.