First Valve Adjustment After Rebuild-Problems

JTO · 01-15-2003, 09:32 AM

Hi All,

I am having a local, well regarded Porsche mechanic perform the first valve adjustment on my 911S after a total powertrain rebuild. He called me to say that the rocker shafts/rockers were not installed properly and needed to be moved so that the "stress groove" or something is inside the rocker housing. He said If we don't do this this, a crack in the housing can result. Other than this, he says the car runs great and is very powerful.

Please comment on this

Thanks,

Troy

john walker's workshop · 01-15-2003, 09:48 AM

rocker shaftposition is often overlooked. it's good that he caught it. sounds like he's on the ball.

JTO · 01-15-2003, 09:50 AM

Thanks John. I was hoping you would respond. He is estimating about 1.5 hours to check and correct the shafts. Is that reasonable?

Thanks again,

Troy

cstreit · cstreit's Garage

That's quite reasonable... It would take me 3-4 times as long

Gunter · Gunter's Garage

Did your mechanic say that ALL shafts are incorrect? By how much? Did he notice some oil leaks from the shafts? It is true that the rocker shafts have a certain position in the casing. Aside from stress, there is the issue of possible oil leaks from the shafts. If all the rocker shafts have the wrong position, then the person who did the rebuild made a mistake. For the re-positioning of the shafts, the engine would need to come out, the shafts properly positioned and re-torqued. This would be a good time to find out if the rebuild included a set of rocker shaft seals (Two per shaft) I would get in touch with the rebuilder and put this issue to him.

I just noticed that your mechanic estimates about 11/2 hours. That seems reasonable but I also try to picture how he could do this with the engine in place. It is pretty akward to reach in there with two Allen wrenches and then use a torque wrench. Are we talking about a partial drop here? Can this be done right in 11/2 hours?

JTO · 01-15-2003, 10:14 AM

Gunter,

Walt (the mechanic) says that as he is doing the valve adjustment and a piston is at TDC, he can loosen and adjust the shaft position. He said it is difficult in the car but it can be done.

Comments?

Thanks,

Troy

Thomas Owen · 01-15-2003, 10:22 AM

You most certainly can do it the car, and 1.5 hours seems fair. Get the cylinder at TDC and the shaft can be loosened and moved. I would highly recommend you talk to the builder (unless that happens to be you!) because this is an important part of valve train reassembly and should not have been left this way. You don't want it to be an indication of the attention spent on other parts of the build.
Good luck,