911SC Oil Leak

booyah911 · booyah911's Garage

Looking for advice on the source of an oil leak. Pretty substantial oil leak from near cylinder six, dropping on the exhaust and smoking.

Just had the CIS out, replaced the seals in the triangle of death, so those are new. No signs of a leak there anyway, and I know the leak predates my recent ownership because it's always had oil dripping on the exhaust in that location. Valve cover gaskets are also new from recent service. Could this be coming from behind the oil cooler and involve the service bulletin/JB weld fix? I'm not sure where the oil comes out, if it is that. Hopefully not! Let me know what you guys think.

proporsche · proporsche's Garage

this looks like you rocker pin-shaft is either loose or misaligned to the wrong bor-side,
If you would take the valve cover of you should not see any oil in this place..on picture.
If yes have a look at the rocker shaft no 6 intake or exhaust.While there check them all ,of course..
your no 6 exhaust shaft position should look like this, for example

Ivan

booyah911 · booyah911's Garage

Great feedback. I just went down a rabbit hole researching rocker shaft oil issues. I knew they had a tendency to back out but didn't know about the oil issue. I'll pull the valve covers off this weekend and inspect. Thanks!

PeteKz · PeteKz's Garage

If you are getting leaks at the rocker shafts, install the RSR O-rings on the shafts.

theiceman · 05-09-2024, 01:31 PM

Quote:

Originally Posted by proporsche

this looks like you rocker pin-shaft is either loose or misaligned to the wrong bore-side,
If you would take the valve cover of you should not see any oil in this place..on picture.
If yes have a look at the rocker shaft no 6 intake or exhaust.While there check them all ,of course..
your no 6 exhaust shaft position should look like this, for example

Ivan

yup i had to do all this after i rebuilt my engine because i didn't replace the shafts, it was leaking exactly as ivan points out and running down the back side.

mike sampsel · mike sampsel's Garage

Quote:

Originally Posted by PeteKz

If you are getting leaks at the rocker shafts, install the RSR O-rings on the shafts.

And if you are installing RSR seals (which most recommend) get some of this to put a dab of lube on the seals. It's o-ring grease. Useful on the injector seals and other o-rings too. And the torque on the used shafts is higher than the new ones (around 18-20 ft lbs) on the used shafts for torque (keep them in place).

https://www.amazon.com/gp/product/B00IKUIO82/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

There is no way I'd try to do the rocker shafts with the engine is SITU, I must drop the engine to get the room to do the job. But, if your only doing one,and your back is strong, and lots of space for words of woe then it can be done in SITU.

GG Allin · GG Allin's Garage

Check your cam tower plug also. On a fresh build recently I had a leak on initial start up that was from mine not being tightened all the way. That's exactly where it was dripping from.

booyah911 · booyah911's Garage

Hmm, rocker shafts are in the correct position and tight along exhaust 4-6. No oil in that part of the vc shown above. The tower plug around cylinder six is also tight. Any other ideas? The vc is flat and not warped. I also believe all of the vc nuts were tight when I took it off.

proporsche · proporsche's Garage

That is good....but have you checked the intake side?You might as well since you are on it...
If not that take a picture where the cyl head meets the camshaft housing,that is the only place for this kanda drop of oil-leak.Also put your hand on the oil return tubes ,if you can spin them -the o rings are gone But if that would be leaking you would see this on the inside of the heat exchanger

Ivan

mike sampsel · mike sampsel's Garage

While your in there, check to see if the exhaust head studs are broken.
Pictures of the exhaust shaft positions, for posterity are nice too.

booyah911 · booyah911's Garage

I'll check the intake and exhaust studs tonight, thanks. Here are some photos of the rocker positions. Hard to get good photos, but the rocker bolt is flush or just proud of the thin side and well inside the thicker bore.

booyah911 · booyah911's Garage

One more:

proporsche · proporsche's Garage

looks fine but..this place under the 6 exhaust.Is that a piece of old gasket leftover??

booyah911 · booyah911's Garage

Thanks, proporsche, I noticed this too and will clean it up with a scrotchbrite before reisntalling. I slide my finger over it and its almost imperceptible, but maybe addressing will help.

I checked the intake side of 4-6 and it looks like each of the rocker shafts is improperly installed. They are all tight, but the shafts are flush with the BIG bore side, which I think is incorrect. That said, I don't see evidence of oil leaking down from the intake side to create such a big, dripping leak on the exhaust side (but maybe I'm just not seeing it).

One of the eight head studs on the 4-6 side was also slightly loose, by about a quarter turn. Others were good. Do we think the leak could just be from the gasket remnants? That would be great.

proporsche · proporsche's Garage

yup that is your problem..Just make sure when you relocate it the crank mark points to that cylinder.
It is kinda PITA on the intake when you have the engine in car but doable.Also adjust the valve clearance..and check all other rocker shafts...
And yes that is your oil leak....good luck ..you be fine after this repair

Ivan

booyah911 · booyah911's Garage

Ugh, not looking forward to fixing this. Just replaced the airbox/CIS with the engine in, so let the adventures continue, I guess! I'll keep you posted. Much appreciated!

proporsche · proporsche's Garage

consider yourself lucky this could have happened.I had to do the whole engine for a friend.
Looks like you have nice garage, i would remove the engine-no need to remove it with the trany.

It will be much easier to work on it.
I think the shafts traveled in your case..here broken spring & bend valve on the 911 i have mentioned

mike sampsel · mike sampsel's Garage

Quote:

Originally Posted by proporsche

i would remove the engine-no need to remove it with the trany.

It will be much easier to work on it.

I've pulled my engine a few times. Both engine and tranny every time. I've had problems lining up the engine and the transmission to get them together and as such, I am reluctant to take the engine out alone. I realize it saves some time, but getting things at the right angle to mate the engine and tranny is my concern. Having a lift for the engine where you can get it at the right angle helps a lot, I don't have one.

Think about doing all the shafts with RSR seals if you pull the engine.

proporsche · proporsche's Garage

[QUOTE=mike sampsel;12248455]I've pulled my engine a few times. Both engine and tranny every time. I've had problems lining up the engine and the transmission to get them together and as such, I am reluctant to take the engine out alone. I realize it saves some time, but getting things at the right angle to mate the engine and tranny is my concern. Having a lift for the engine where you can get it at the right angle helps a lot, I don't have one.

I always use single floor jack .If you place it in the middle it is perfectly balanced..
One day i make a video so peeps can see it.No special tools need for it...Plus the alignment is also easy-will make the video too;-)

Ivan

David Inc. · 05-13-2024, 06:01 AM

Having done both I'd say it's much easier to do the engine and trans together. The one time I did just the engine I ended up dropping the trans as well and mating them before putting it back together.

Sure the CV joints are a chore, but it's better than lining everything back up in place, plus the hassle of the electrical connections and inaccessible trans bolts.