What are symptoms of leaking rocker shafts?

[M491Cabriolet]

I was wondering... In reading some books, I noted that the rocer shafts could leak, which would be a problem in that it would cause an oli leak. OK... But I really don't understand. If the rokers are inside the valve covers, wouldn't the vale covers contain the leak? If so, what would the symptom of leaking rocker shatfts be? In other words, from where would the oil actually leak out of the engine? Would it stream from the seals between the cam towers and the heads, or from the valve covers? This might seem like a dumb question, but you know when an o-ring is leaking, if an oil cooler is leaking, or a valve cover gasket is leaking, but how do you know something inside the engine is leaking? Thanks.

[Wayne 962]

The valve covers cover some "open" parts and some "closed" parts. The open parts are where the spark plugs go, and if the rocker shafts are leaking, then oil will be present in there...

-Wayne

[dshepp806]

Maybe to add a visual to Wayne's comments;;;;;;

I, too, wondered with the same question, as the gasket looks to block the leak. This pic is not from my car but used from another site to demonstrate the
gasket related to rocker positioning. Circling (indicated) was drawn by the original pic submitter. Maybe Wayne can speak to the leak pathing outside of the gasket.

Best,

Doyle

[jkh2cpu]

The cam towers are sealed to the three cylinder heads, but only in the narrow area between the valve stems on each cylinder head. The ends of the rocker arm shafts are visible in the non-sealed areas. You must remember that the cylinder heads are individual heads, so there is a small space between each head where the oil can exit the cam tower housing, IF the oil is leaking from the rocker arm shafts. The above photo does not clearly show the openings provided by the adjoining cylinder heads. Oil that has escaped from the rocker arm shafts can also exit the cam towers on the very ends of the cam towers. I've got some cylinder heads and cam towers that I have removed from my project engine (a 2.7 put on hold due to a wedding; first things first ;-) ). I'll try to dig them up tomorrow and snap a few shots to illuminate what I'm trying to explain.

HTH.

John.

[M491Cabriolet]

Thank you! OK, I think I understand. So, my question becomes, if rockers were to leak, where exactly would the leaking oil actually visibly escape? In other words, would the leaked oil dribble out on the bottom back side of the cam tower at the very center point of the head affected with a leaking rocker arm? This is what I have on cylinder five. There is a very definded dribble about 1.5 mm in thickness coming out at the very center of the head on the surface of the cam tower (I can see it when looking from the sump plate toward the outside of the engine). I hope that is expained well enough because I can't take any pictures until next week. Thanks.

[jkh2cpu]

Who knows where the oil will show up when it is leaking! If the car suspension is setup according to Porsche, there is a slight pitch downhill toward the front of the car, so the oil may show up around the number 5 or 3 cylinder, but for all anyone knows, it may be coming out of the left-hand side of number 4 exhaust rocker! I'd try crawling around on the ground with an inspection mirror, and if no obvious points of oil exit were visible, I'd begin to suspect rocker shafts. I know that I can feel oil with my finger when I run it around the cam tower, and there are no obvious signs of leakage, such as from and oil return tube, and my engine is not huffing and puffing like there was a cylinder head lead, so right now I'm suspecting the rocker arm shafts. When I put my top end back together about 15 years ago, I torqued the rocker arm shafts down to 12 pounds or so, which is according to Porsche. I am now to understand that on rebuilt engines, the rocker arm shafts like to be torqued up to around 18 inches or so to reduce the chance of rocker arm leaking. I don't know if I'm going to torque that high, but I do plan to get some rocker arm shaft seals from right here are Pelican Parts and install them when I have some time...

HTH.

John.

[M491Cabriolet]

Oh, I know what you mean. But the engine is completely dry except for a single tiny and well defined stream of oil that comes out at the low point (the sort of U-shaped protrusion on the head) of the center of the head but is on the backside of the cam tower surface. When it gets to the bottom edge of the cam tower housing, it flows forward toward the oil cooler and drips off of the front bottom corner of the cam tower housing just near the oil cooler. One drip at a time. By the way, I have the heat exchangers off the engine to be able to have a perfect view. I have no doubt of the point where it comes out. I'm thinking rocker shaft. What do you think? Thanks.

[dshepp806]

There's boatloads of info on this rocker situation, well worth the reads.......I'l,l try to compile my findings, soon, for you,..as I'm, (too) preparing to have a look at this situation....when I drop the VCs....

Thank God for the good graces of the board contributors........TroyGT had some great commentary re" rocker arm failures...good stuff,..a helpful fellow.


I'm now ready, thanks to this board, to engage my project,..she's tapping heavily (10K ago Valve adjustment,...maybe a crappy lock nut,..? don,'t know but am better prepared to gauge the rockers when the VC's come off,...a piece at a time, I guess. Thanks to Wayne's book and other threads presented here...good stuff.

Thanks to all,

Best,


Doyle

[jkh2cpu]

Here are a few shots that I promised last night.



This is looking down through the cam tower, and the heads are visible below. You can see two adjoining heads in the center of the shot.





This is how the head are arranged. I simply removed the cam tower without disturbing the heads. You can see the area that is sealed: it's between the valve stems, and it's a lot cleaner that the rest of the head, which can be exposed to all sorts of debris.





This is the backside of the cam tower, and the two oil return tube holes are at the bottom of the cam tower. Some sealing material is still on these cam towers.


The ends of the rocker arm shafts are not in the sealed area, and if much oil is leaking, the oil will dribble out where gravity takes it, which may not be close to where it started ;-)

HTH.

John.

[TroyGT]

Yep... been down this road. Precise engineering is the only thing keeping the engine from leaking oil. When things get a little worn, sometimes the shafts/bores get scarred up a little and that can allow some oil to the outside. For me, it looked like my oil cooler had sprung a leak. Regardless of what you find when you get in there or if you have to perform and replacement/repair... put some RSR seals in there. They don't hurt a thing, they're easy to install, they're cheap, and they will catch oil when the precision engineering gets a little out of spec. You can even put them on while the engine is in the car! Porsche used these on their race cars so they could pass tech inspections... if they're good enough for a race team... they are definitely good enough for me. I just had my engine out recently... mostly because I had overtorqued the rocker shaft bolts trying to stop the leaking... which later resulted in a rocker boss failure... (not pretty). Car was down for 9+ months while I found a replacement cam tower, rockers, pulled the engine and re-installed everything again. My lesson, unfortunately, was learned the hard way. So... this time while I was in there I put RSR seals on every shaft and my brand new garage floor is bone dry.

-Troy