Pelican Parts
Parts Catalog Accessories Catalog How To Articles Pelican Tech Forums
Call Pelican Parts at 888-280-7799
Get FREE Ground Shipping with the purchase of $179 in qualifying parts!
> Valve Adjustment
> Shifting Improvements
> Jacking Up Your 911
> Fuel Filter & Accumulator Replacement
> Steering Bushing Replacement
> 911 Forum
> IMS Bearing Replacement
> Air / Oil Separator
> Coolant Flush
> Spark Plug and Coil Replacement
> Brake Pad Replacement
> Boxster Forum
> Water Pump & Thermostat Replacement
> MAF Sensor Replacement
> Fuel Line Vent Valve
> Air Conditioning Maintenance
> Auto Transmission Fluid Replacement
> 996-997 Forum
> Blower Fan Replacement
> Fuel Pump & Filter Replacement
> Air Filter Replacement
> Hatch Shock Replacement
> Glove Box Catch Replacement
> Cayenne Forum
> View All Porsche Tech Articles
> Classifieds
> Accessories
> Porsche Parts List
> Porsche Events
> Cars for Sale
HomeTech Articles > Fixing Oil Leaks...

Pelican Technical Article:

Oil Leak Fixes in the 911

Mark Jo

[Click on Photo]
Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

Figure 9:

Figure 10:

Figure 11:

Figure 12:

Oil Leak Fixes

  • Oil Thermostat
  • Oil Breather Cover
  • Oil Cooler (Engine)

 This article reviews a couple oil leak fixes that are common areas of leakage for older Porsches.  The car used for this is a 1982 911SC.  Techniques may vary from model year to year.

Also these are repairs that are done with the engine out of the car.   I did these while doing a clutch repair.   I have heard that the oil thermostat and the oil breather cover can be done with the engine in the car but necessitates the removal of the entire CIS system.  The oil cooler involves either a full or partial engine drop. Partial and full engine drops can be found at the technical article section.

 With the engine out of the car looking at the flywheel end of the engine we can proceed.  In Figure 1 you can see the 3 points of attack labeled.

Oil Breather Cover

If your engine was anything like mine there should be a puddle of oil here around the breather cover.  If not this may not be an area of leakage, but it is a common one.  If you look carefully (FIGURE 2) there is a sensor with an electrical connection coming out of the cover.  Unplug the electrical wire at the end of it, and screw it out.  Then there is a bracket connecting your accelerator linkage to the air box.   Be careful taking this off because if the rubber of the air box is old it will snap off (like it did for me) but can be repaired with epoxy.  It does not look like it is vital, just a support bracket.  After that you must go ahead and remove the whole accelerator linkage plate to be able to get your wrenches at the oil breather cover nuts.  From here it may differ from engine to engine.  A BBS member said that for his Carrera 3.0 he had to remove the whole CIS system, but on my car I was able to do it with a little bit of cheating.  You can see that even with all the nuts loosened and removed, the breather cover cannot be lifted because of the pipes above it.  And with some careful observation you can figure out which clamps have to be loosened so that the pipe system and the round gold modules (Vacuum modules?) can be removed as a unit (FIGURE 3, 4).  Hose clamps have to be undone at the junction directly above the oil breather cover then at the multi junctions above the oil thermostat, and also over on the side of the engine.  When all the hose clamps that need to be loosened are, and the 2 support brackets holding up this network of tubing are undone, the tubes can be pulled off.  But even with this, the breather cover still does not have the clearance to be lifted clear of its studs.  So to solve this, I undid the intake manifold nuts on the 2 most flywheel side cylinders (FIGURE 4).  And I was able to tilt the intake system enough to remove the breather cover.  With the breather cover off, put it on a level surface like a piece of glass to check for warpage or unevenness.  If so you can place a piece of sandpaper under it, still on the piece of glass and sand lightly to level it.   If it is bad, you will have to purchase a new one or have a machine shop level it for you.  The gasket for the cover was purchased at  The one I pulled out was cracked in several places leading to the oil leaks.  To prepare my gasket I coated with a light coat of motor oil, but I have heard different opinions.  Some say install dry, and other use a Loctite gasket sealer.  If I were doing this again I would probably use the Loctite, but my oil-coated gasket seems to be holding up.  Installation is reverse of removal.  But do not put all the parts together yet.

Oil Thermostat

To the right of the breather cover is the oil thermostat.  It looks like a circle with 2 tabs for the nuts holding it in place (FIGURE 2).  Directly in front of it is the oil pressure sensor that needs to be removed.  Then the removal of the Oil thermostat is straightforward.  Undo the nuts and lift it straight up.  If the thermostat comes out easily, that means the o-ring is worn and is no longer sealing.  But even so changing this o-ring is cheap insurance when the engine is exposed.  Roll off the o-ring, coat the new one with a coat of motor oil, and slide the thermostat back in.  You should feel some resistance indicating a properly sized and sealing o-ring. 

Engine Oil Cooler

To tackle the engine oil cooler o-rings we have to be able to support the engine, and remove the passenger side heat exchanger.  If you engine is on a stand, no problem, but I worked on the ground by supporting my engine on the driver’s side and the middle of the crankcase.  You should also put some support under the passenger side heat exchanger to be safe.  For information on heat exchager removal see the tech article on heat exchanger backdating at  Once the heat exchanger is removed securely support the engine from both the sides and middle.  The lower 2 oil cooler nuts should be exposed.  Also take off the white-ish oil cooler shroud on top of the oil cooler (Figure 1).  This should expose the two upper oil cooler nuts.  Put a turkey roasting pan under the cooler because there will be a lot of residual oil in there.  Once the cooler is off you will be able to see the 3 o-rings.   Two are the same size the other is different (Figure 5).  These o-rings can be purchased at  Coat these rings with motor oil and install.

Now you can reinstall everything and you should have solved 3 major areas of oil leaks.  If leaks persist, clean off you engine bottom with a degreaser or brake cleaners and then you can better track down the source of the leaks.  Other common areas are any junctions between oil line, or the oil line and the crankcase.  Also culprits are the oil return tubes that can be replaced using the tech article available at 

Comments and Suggestions:
John Comments: I purchased from Pelican the three seals to replace in my oil cooler to engine interface. My car is a 1973 911 S. When I removed the oil cooler I found an ATV sealant use with the seals. My question when I am putting in the new seals should I also use an ATV or do as your tech instruction say and only soak them in oil and put them in? I do not see any surface scratches or any thing else that would indicate damage that would require the use of an additional sealant.
July 26, 2011
  Followup from the Pelican Staff: You only have to soak them in oil. Do not apply any sealant to O-rings. - Nick at Pelican Parts  

Got more questions?  Join us in our Porsche Technical Forum Message Board, and ask a question to one of our many automotive experts
About Us
Pelican Parts, LLC
1600 240th Street
Harbor City, CA 90710
Order Online or Call:
Sign Up for Pelican Pit Stop News & Special Offers
Copyright 2017 Pelican Parts, LLC
DMCA Registered Agent Contact Page