Found source of my oil drip, but what can I do?

[tbitz]

After much cleaning a looking under the car I think I found the source of my oil drips on the heat exchangers. It seems like it is coming between the cam housing and the heads. What can I do? Should I try and re-torque the cam housing screws?

My oil drips are not the valve covers (top or bottom). I am certain of this.



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Tony
'78 911SC

[GIBSON]

Tony, it's possible your leaks are coming from the rocker shafts, this is a common place to see oil when these shafts leak.
It's not that commong for the cam tower/head interface to leak oil. You can check the torque on the shaft nuts but most likely you will have to take them out and install seals on the shafts (Pelican sells them). My experience is that this leak is quite common, it's usually caused by improper torque on the shaft sealing nuts. Also, failure to install the shaft in the center of the bore can do the same thing.
See what other advice you get but my guess is rocker arms.

Bruce Herrmann
73911S

[Nick L]

How hard is it to replace the rocker shaft seals?
Does the engine have to come out?
What is the procedure?
Thanks!

[GIBSON]

Tony, these seals can be done with the engine in but it's a pain. You just about have to remove the cam chain boxes to get the #1 and 6 shafts out. You will need
an aluminum drift to tap out the shafts and ideally a small torque wrench (1/4 in drive, snap-on makes a great one). You will find the job much easier with the engine out as you can better tell when the shafts are in the middle of the bores, an important measurement. When you get the shafts out, inspect them for wear, grooves etc. The seals install in grooves already in each shaft, seems like it should be part of any engine rebuild but most of the time they are not used until a leak is discovered. They will not fix a scored bore or shaft that is
scratched or otherwise unservicable.
I'm going to do the same thing in the next month as I'm tired of the same leak you've got, it drips from the forward edge of the cam tower right onto the heater box.
I'd suggest an engine removal as you'll fight these things with it in place.
Bruce

[john walker's workshop]

you don't have to remove the chain housings for #1 and #6 shafts. just move the shafts inwards. use a crowfoot, and a screwdriver to lever the crowfoot. cam tower to head leakage is real common. wait til you need a valve grind or head studs. close to the same labor.

[GIBSON]

I would defer to John's experience on cam tower/head leakage. It might be nice to prove once and for all where the leak is coming from. I have a friend who uses an oil additive which shows up under black light, he says it makes it easy to find the source of leaks. If it is the cam tower, at least you will know what you have to do to fix it. Just in case, you might consider a complete top end job to be sure you catch it all. It's not that much more to do to remove the towers and re-seal. The new sealants are much better than what you car probably has in it now. If the drip is not to annoying (hard to ignore if it's dripping on the heater box) you might want to wait until more comprehensive work is needed.

Bruce

[Wayne 962]

If it is leaking there, then you need to tear down the top end, and reseal. You also need to check the case. If the case is warped, it will cause a leak there too. This is a bad-news leak and will be lots of time and energy to fix.

If the rockers are leaking, you can install the rocker seal there. These seals are NOT a factory part, and are not on most motors (they are actually an RSR racing part). They are a good quick fix for rocker leaks.

-Wayne

[tbitz]

Gibson,

I think you are right about my leak. My leak is exactly as you described it

"drips from the forward edge of the cam tower right onto the heater box."

I got the following picture from Bruce Andersons book. The arrow indicates where the oil would be dripping if the rockers are leaking.



The following picture shows a detail of the rocker shafts. The dimesion "A" is spec'd at 1.5mm(0.06"). What is the point of the groves ? It doesn't look like there are "O" rings in there.



I think I'll start with the right exhaust rockers as it is the easiest to access. The intakes will be a pain to look at.

Thanks for the pointers. I'll update with my findings.

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Tony
'78 911SC

[This message has been edited by tbitz (edited 07-16-2001).]

[This message has been edited by tbitz (edited 07-16-2001).]

[This message has been edited by tbitz (edited 07-16-2001).]

[This message has been edited by tbitz (edited 07-16-2001).]

[This message has been edited by tbitz (edited 07-16-2001).]

[Natchamp]

Tbitz, Wayne is right, most of the motors don't come with the o-rings. They are special RSR parts used for racing. The rockers (which simply use the same casting/maching process to reduce manufacturing costs) are the same. When I found this out during my project, I could never think of why they just didn't come on all motors, they cost peanuts, easy to install and apparently work (I'll let ya know).

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Mark
The Beast
mark@hargett.com

[tbitz]

I could not find them on the Pelican page. What is the dimensions of the O rings? I can just pick these up at the local auto parts shop.

Bently spec's the torque for the pich bolt as 11lb-ft, but Bruce Anderson's book says 15lb-ft (page 130). Which is it (does it really matter).



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Tony
'78 911SC

[GIBSON]

Tony, I've used Bruce Anderson's figure before,it seems about right, I'll check the factory manual and see what is says.
It is strange that more motors don't get these, although most seem to get by without much problem. I think I'd install them without question, it makes sense. Porsche reserved them for race engines, probably due to the high rpm's seen on these motors.
Just install the shafts according to the illustration you included and you should be fine. Inspect each shaft before installing, some of the older shafts will show a little cracking at the very end near the pinch bolts, I would not trust them- toss those and use new ones. While you're at it, check the rockers for wear, might as well check as much as possible while you're at it.

Bruce Herrmann

[Jens Wendorff]

If you need, I can get you the Part No. Just takes awhile to dig it out. The O-Rings can be purchased by Porsche if you have the number; they are not listed in the usual micro-fiche though.

Jens

[tbitz]

Jens,

Can you post the O ring part number.

Thanks,


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Tony
'78 911SC

[Nick L]

OK, I'm confused.
Can you install the o-rings while the engine is still in the car, fairly easily??

[Jens Wendorff]

Here you go:

The Porsche O-Ring Part No. is 911.009.103.52

Jens