What's causing this leak ?

[on air]

what is causing this leak on the left side? I just had my mechanic do a valve adjustment, he replaced the upper and lower valve gaskets. He also did a partial engine drop and replaced the oil cooler seals and didn't notice any other areas that needed attention.

There were no leaks at idle or when he ran it at 2,000 rpm in the air. But after I drive it on the road and then park it about an hour later oil drips here form. I took it back to him already once, he couldn't get it to form a leak again. I drive it home and the drips form.

[kwikt 911]

Rocker arms shafts leaking or cam housing.

[tito911s]

Might want to share with us more specifics to help. Left side? Meaning passenger side? I'm guessing that since you mention oil cooler deals with are on that side. Have you looked at the triangle (breather hose, sending unit,...). You may just need to tighten the valve cover bolts a bit as they could be dripping from there. Above advice is also good -- could be leaking off rockers (install RSR Seals) or from the housing. Most troubleshooting requires cleaning area well, running car and looking for leaks. Good luck.


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[Bob Kontak]

Originally Posted by tito911s

Left side? Meaning passenger side?

As you know left side is driver's side in the US. LHD cars.

"Side" is always determined from the rear facing front. Only stating this so there is no confusion.

I am not able to tell from the picture the location.

Maybe a pic a little further back with a finger point?

I do know that replacing the seals on the cooler are a PITA with a partial drop. Not so much getting the seals in but getting the fasteners on. Access.

[on air]

The leaks are on the left (driver) side and forming along the front edge corner of where lower valve cover/cam tower area. He looked at the other items of 'triangle of death' but only thought the oil cooler needed attention. He couldn't get it to leak at idle or running while looking at it at 2,000 rpm. The leaks start showing up after a bit of town/highway drives and after car sits for about an hour.

[tito911s]

As kwikt911 said, it could be leaking off rocker arms. installing RSR seals might fix the leak. But it might not. I have similar symptoms on an 84 911 and have replaced oil return tubes, performed valve adjustment, checked head studs (to see if any have broken)...nothing has fixed my leak. I'm now concerned that I have a leak at the cylinder to case gasket, which will require pulling the engine to fix.


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[DRACO A5OG]

Most likely, rocker arm shafts.

You really should confirm for yourself the shafts are in the proper position and torque them to 20 ft/lbs

Your wrench probably did not inspect them, they never do

or you may get this:

You Must CHECK the Rocker Shaft Bolts when you DIY Valve Adjust!

[Marc Bixen]

Everyone wants to think the worst. Possible oil return tube seals??

[TibetanT]

Hello There:

Check your cam tower inside the engine compartment near the oil line. Could be the seal there.
Just my .02 cents.

And, like above ^^ could be the oil return tube's seal causing this.

[Trackrash]

Mine does the same thing. I have chased that leak for years. I replaced my cams and re-installed the rocker shafts, (no way they could leak that much anyway), new oil return tubes, many new valve covers, etc.

My guess is it is the joint between the heads and the cam housing.

[on air]

Thanks all. I have an appointment on Monday with another shop with a very experienced 911 guy. I'll report back soon

[yelcab1]

Originally Posted by Trackrash

Mine does the same thing. I have chased that leak for years. I replaced my cams and re-installed the rocker shafts, (no way they could leak that much anyway), new oil return tubes, many new valve covers, etc.

My guess is it is the joint between the heads and the cam housing.

And that cannot be easily fixed with the engine in the car.