Rocker Shafts

Seth Slovik · 06-21-2001, 03:57 PM

I have had an ongoing problem over the last couple of years with my #6 exhaust rocker shaft working it way out of it's bore. I realize that it is probably because of wear on the bore, but I was hoping that someone has come across a solution to this problem. I have replaced the rocker shaft and the supporting hardware, used loctite in the bore and even gone as far as using loctite 640 which seems to made just for this problem but I had this happen to me again today. Any suggestions as to what to try next?

Thanks,

Seth
82SC Euro

Hatari · Hatari's Garage

It's not easy because of the tightness or lack of room, but are you torquing to spec? It takes a 1/4" torque wrench to get in there and the books say they can work their way out if not torqued to spec. I just did a top end on a 2.7 and I'm paying very close attention to this too.
Jack McAllister

Seth Slovik · 06-21-2001, 07:13 PM

Jack,

I have tried tight, real tight, real real tight and over tight, I have gone 6 months at some times between problems but it always seems to return. I have resonable access as I have a test pipe in place of the cat.

Seth

roGERK · 06-22-2001, 05:04 AM

Seth, you've probably tried this already but Bruce Anderson mentions a couple of small "o" ring seals that fit in the shaft slots.

Apparently these seals were developed for racing - Anderson gives a part number which I could look up for you.

Unfortunately, the seals were developed to prevent oil leakage, rather than to keep the shafts in place.

However, they might be worth a try...

- roGER

Hatari · Hatari's Garage

Guys,
I just installed those o-ring seals in my 2.7 rebuild. I am confident they will assist with minimizing oil leaks around the rocker shaft bores (and mine showed signs of slight blemishes), but I am sure, due to the durometer of them, they cannot help much in the way of holding the shaft...they are designed to conform to the imperfections in the bore, so they are soft.
Jack McAllister

john walker's workshop · 06-22-2001, 12:40 PM

sounds like you're putting off the inevitable. you need to replace the cam tower. but you knew this.

Wayne 962 · Wayne 962's Garage

Right, we sell the rocker seal in our catalog, but it will not help with the rocker backing out. Sounds like it was loose at one time, and then enlarged the cam tower bore.

Sounds like you need a new cam tower to me. I think that they use the same ones as the earlier cars, so you might be able to get one without paying a fortune...

Actually, just checked it - the Carreras and the SCs use the same cam tower...

-Wayne

Seth Slovik · 06-22-2001, 02:19 PM

Thanks Guys for the suggestions, John hit it right on the head, I am puting off the inevitable changing of the cam tower and all the labor involved. I am going to try again to use the Loctite 660 Sleeve Retainer as it appears to made for this type of application. If someone has heard of slightly over size shafts or the end "cones" please let me know.

Thanks,

Seth

Leland Pate · 06-22-2001, 02:34 PM

Just a quick question....
What are the indicators that a shaft is moving from it's intended location?

Seth Slovik · 06-22-2001, 03:54 PM

Leland,

In my case you could hear a loud valve tap that gets progressivly louder as the shaft works it way out and the valve clearance get larger. If it comes out all the way the rocker shaft can come off (not likely).

Seth

Roland Kunz · 06-23-2001, 04:28 AM

Hello

All 1968 -1989 will fit. Left and right are similar base design but you have to swap the oil tube. turbo cam tower have one bearing more on the cam.

There are some cheap fixes for "people who stranded in the middle of nowhere".

I better don´t tell them as they will become a usiually repair methode then. But imagen the problem would happen on a rally or endurance race. You have to make someting for the last kilometers.....fast solution. Do or die.

Grüsse

mackgoo · 06-23-2001, 06:01 AM

Check this out http://www.pelicanparts.com/ultimate/Forum12/HTML/003333.html

Seth Slovik · 06-23-2001, 06:21 AM

Come on Roland, lets hear the quick fixes because my alternative is to pull the motor and do major surgery. I was thinking drilling and tapping in a couple of set screws, not too much different from what the factory did on the new 911. My motor has less less than 20K miles on a recent rebuild so I have no reason to go in and do other things to it.

Thanks,

Seth

[This message has been edited by Seth Slovik (edited 06-23-2001).]

Roland Kunz · 06-23-2001, 07:04 PM

Hello

OK just some fantasys. It will not hold for eternety.

Cylindr 6 Exh:

Remove oilcooler. Remove shaft. tape everything. Use a short M20 tapper and tap aprox 1 cm inside the hole. Then you plug it with a M20 DIN 910 plug. Now before you do this you have to messure exactly how far you can go in. The shaft hast o sit flush at the plug. So the way is insert the shaft and look it to position then plug the end to the oilcooler. Now as far I rmember the oilcoolerside is very far out asymetrical. Maybe not enough flesh for my solution then you have to go your way. But the set screw will crack the wedged ends after a while ( BTW did you checked yours for a crack ? ).
And not to confuse the 993 has hydraulic lifters and other shafts to get oil into them. If you will go that way you can adopt the 993 parts but need the special pre filter deleting the cooler.

An other way would be to make an turned fillment with a flange and bolt that on.

Now back to the inner end:

On the other side you can´t tapper as you would have to remove the chain housing to get trough the other holes to drive the tapper.

So you just messure the distance beetween the two shafts from Cyl 5 to 6 and get a 18 mm tube. Pusch it trough #6 onto '5 and then insert the shaft and try to fix it with only turning the bolt ( Works normaly you have to pretourqe slightly before inserting ). Then plug that end.

If you can´t fix the shaft then you remove the tube again and get some solid 18 mm cylindrical rollers. Drill a thread in them and use a long thred rod and poly lock nuts to spread them inside to the propper distance.

To avoid oilsiping use a good sealer inside the hole.

An much "simpler" thing is to use a special two component "glue" used for aluminium construction on Audi Bodys. Just place the shaft and fix it, sand the remaining holew all, clean it with brake cleane. Then fill the holes with the2K stuffd and put two plates over the holes. Hold them with a vice togehter and heat up the area to 200°C.

Maybe better drill a little hole into that chamber so the gases can vent and the material will come up in that wisthler.

The low on that is you have no chance to return. If you have to remove the shaft you musst drill up one end or use a chissel and a punch and brake the rocker to get acces to the nut under it.

Said things are Pfusch, but on the highest level............
If you don´t have to count your labour and you like to conquer new land it is up on you.

Auf ein gutes Gelingen !

Grüsse

Seth Slovik · 06-24-2001, 09:34 AM

Thanks Roland, It seems to me that a little innovation and some imagination go a long way. I just cleaned everything up real well, knurdled the ends of the rocker shaft slightly and re-incerted the shaft into the bore with loctite/permatex 660 sleeve retainer and I tightened the **** out of it. If it fails or even if it works I will re-post for the sake of people using the archives to solve this same problem.

Thanks Again,

Seth