Has anyone attempted replacing the valve seals/valve guides on 955? Ive noticed over the last few months that mine has started developing the typical symptoms associated with this needing replacement, which is no surprise with the mileage I've put on mine.


Did some online searching and seems from a post by Mr. Haney that the valve guides aren't even available from Porsche... Anyone know about the seals or have any experience doing this or having it done so I know what I may be getting myself into?


Thanks.

 

You could replace the seals as they are readily available. It would require removing the camshaft housings, camshafts, lifters. Etc.

I feel that if the guides are that worn, New seals wouldn't last that long. Without a tight guide to support the valve stem it compromises the valve seat sealing ability, has a large impact on heat transfer from the stem to guide and valve head to seat. Oil leaks past the stem and drips down the valve backside, forms carbon between the valve seat and valve, further reducing heat transfer and sealing....Etc. I'd like to know what other 4.5 CTT engines look like in this area around the 180k mark. On my engine, the exhaust guides were totally worn out while the intakes were great. Most of my exhaust valves had between 4-8 grams of cement like carbon fused to the backsides and I'm sure it wasn't helping flow. Needless to say they will be getting replaced with Ferrea super alloy valves and the best guides money could buy.

 

Im not sure if the guides are worn.. It may only be the seals. I don't think there is a way to tell if its one or both without tearing it down, is there? Im just under 180k so if I decide to tear into this I will get some pics to document the condition. Any idea if there are any special/Porsche-VW-Audi specific tools required, or would this be fairly straight forward job?

 

Moving this thread to the new Cayenne Turbo section with a permanent redirect...

 

You would need cam holder plates to set the timing , an air hold adapter to hold the valves up when you remove the springs unless you remove the heads. A dial indicator to get an idea of valve guide clearance. Imo, not really worth it. Depending on mileage your engine is probably getting loose anyhow. These engines can go a long time but what a lot fail to remember is that it is a boosted 450hp forged engine. It's kind of a lot to ask to chip them, overspeed tiny journal bearing turbos, force a bunch of overheated air in and then expect them to stay tight over 200k miles. What I found is that Porsche only put piston offset on one bank and the other wears quite a bit more. Mine wasn't even burning that much oil however the ring lands and oil ring expander were packed with carbon and gook. To me it looks like the issues on these engines are piston to cyl clearance, ex. Valve/guide wear, and chain stretch. Just some food for thought.