pulling rocker shafts on M30 [Archive]

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beetos

02-16-2007, 12:25 AM

Hey guys
Is is possible to pull the rocker shafts out of an M30 E34 without pulling the head? i.e. removing radiator etc.

Cheers

Martin in Bellevue

02-16-2007, 12:41 AM

Not the rear shafts; firewall is in the way. Honestly, I don't think the front shafts will clear the radiator & core support, but there might be enough wiggle room to get the rockers out for #3.

Did we have an occassion to rev too much? How 'bout some pictures & specs on that turbo setup?

beetos

02-16-2007, 01:00 AM

Robin-535im

02-16-2007, 01:38 PM

Cheers,
Had a feeling it would not work.

Its carnage under the rocker cover, both arms on #4 have broken, makes me very concerned that 2 arms on one cyl have gone. Was not revving hard, just pulling 5,000 rpm when it started running on 5.

Head off time.....:(

I'm in the process of doing the exact same thing.

I THINK you can get to the fronts if you can tip the engine up (disconnect drive shaft and mounts) and perhaps remove the radiator. Have to look to be sure, but I'm pretty sure you don't have to do as Bently's says and pull the whole dang cam shaft. I pulled the head to check the valves (got a broken exhaust rocker on cyl#2). Looks like you can position the cam at the right spot, slide the rocker arms to the side and get enough slack to free the rocker arm.

Oops - I see you're concerned about #4 though, so no dice there. Remember to mark the location of your cam gear teeth WRT the head with the crank at TDC before taking the chain off. The chain can slip teeth on the crankshaft end, when the tension is out, so even if you're really careful not to move anything it can still accidentally slip and be off. Don't ask me how I found that out... :)

Kalevera

02-16-2007, 01:44 PM

Guys, the head has to be pulled. The rocker shafts are keyed in to the head bolt holes.

Without removing the head bolts, you can't remove the shafts.

The other issue is that the valves have to be compressed to pull tension off of the shaft and the cam shaft to do any kind of mild head work, and the valves can't be compressed enough with the pistons in the way.

And the rocker shafts are specific to each corner, so be sure you keep track of what comes out where.

beetos

02-16-2007, 06:18 PM

Roger that......

thanks for the valuable feedback.

George M

02-16-2007, 06:40 PM

I have had the head off my M-30 for reconditioning. As mentioned...another affirmation that the head has to come off to remove the rocker shafts...rear shafts in particular. I didn't pull the rocker shafts off but as mentioned, don't think you have to pull the cam to pull the rockers. Reason is...as mentioned, all you do is walk the rocker shaft...the one you need to get at your broken rocker...by pulling the shaft out by rotating the cam off the particular valve starting with most inboard valve...in back that would be cylinder #4...pull rocker shaft...cylinder #5 off lobe...walk the rocker shaft...cyl#6 etc until the rocker shaft is free.

Lastly, you don't have to be concerned about the position of either the cam shaft or the crankshaft once the head is removed contrary to what was written above. I rotated both crank and camshaft quite a bit when I had mine apart for cleaning and adjusting the valves prior to setting the head back on. But before you set the head back on, be sure to have no.1 cylinder at top dead center and the camshaft sprocket hole at 7 o'clock. To ensure you are not off a tooth...make sure when you have this orientation that all slack is out of the driver side of the timing chain. This is a common mistake and therefore easy to degree the cam a tooth off. Timing chain a rope on the driver side...engine at TDC for no.1 and cam sprocket hole at 7 o'clock and you are good.
HTH,
George
Kind of miss the old girl car...engine after rebuild:
http://i26.photobucket.com/albums/c122/biker7/PassFrtOblique.jpg
http://i26.photobucket.com/albums/c122/biker7/headresize.jpg
http://i26.photobucket.com/albums/c122/biker7/M30FullView.jpg

beetos

02-16-2007, 11:42 PM

Wow, that is one clean motor. Looks amazing.

George M

02-17-2007, 05:19 AM

Wow, that is one clean motor. Looks amazing.
Thanks. Gotta love the big six...a marvelously simple motor.
Your car looks like fun!
Cheers,
George

beetos

02-17-2007, 08:55 AM

George M

02-17-2007, 09:53 AM

Thanks George, its a love hate thing at the moment and it costing me a small fortune, but fun is one thing its got in spades. Looking forward to getting her going again once the broken rockers are put right.
Beetos, the broken rocker issue with the big six has been experienced by other board members. One thought is broken rockers can be symptomatic of valve springs that have lost their spring rate inducing float. If you go to the trouble of pulling the head off...not that it is that big a deal if you like to hot rod these cars...but if you plan to run your engine hard and at high RPM, consider changing the valve springs. It could be debated that the rocker arms themselves have a fatigue life and it is hard to identify what precisely causes your failure but rockers have broken before on the big six.
Good Luck,
George

Robin-535im

02-17-2007, 01:38 PM

...Lastly, you don't have to be concerned about the position of either the cam shaft or the crankshaft once the head is removed contrary to what was written above. I rotated both crank and camshaft quite a bit when I had mine apart for cleaning and adjusting the valves prior to setting the head back on. But before you set the head back on, be sure to have no.1 cylinder at top dead center and the camshaft sprocket hole at 7 o'clock. To ensure you are not off a tooth...make sure when you have this orientation that all slack is out of the driver side of the timing chain. This is a common mistake and therefore easy to degree the cam a tooth off. Timing chain a rope on the driver side...engine at TDC for no.1 and cam sprocket hole at 7 o'clock and you are good.
HTH,
George

Good to see you on the board again George, what's new?

By my count, it's actually 7:40... I believe the top cam gear bolt hole is aligned with the head "vertical" centerline axis (i.e., if the head were flat on a bench) when at TDC, which by my count puts the key at two teeth CW of 7:00 proper, 36 teeth = 20 minutes per tooth.

I would LOVE to be corrected about this though... before I put it back together!

- Robin

Kalevera

02-17-2007, 01:47 PM

George, I think the problem is that they're just cheaply made. I've had one break on me (FEBI/bilstein brand) during install. The dealers source some other brand, I forget who makes it, but I think it's lemforder/sachs/boge. Can't remember at the moment.

George M

02-17-2007, 02:55 PM

Good to see you on the board again George, what's new?

By my count, it's actually 7:40... I believe the top cam gear bolt hole is aligned with the head "vertical" centerline axis (i.e., if the head were flat on a bench) when at TDC, which by my count puts the key at two teeth CW of 7:00 proper, 36 teeth = 20 minutes per tooth.

I would LOVE to be corrected about this though... before I put it back together!

- Robin
Hi Robin,
Just trying to make it through this long winter so I can indulge my passion of machines out in the fresh air. More snow today...dam.
As to degreeing the cam...believe you are correct. I was going from memory when I did mine. The sprocket orientation is quite clear but since the camshaft spins once for every two revolutions of the crank, pretty important to put the sprocket with the I.D. hole in the proper quartile :p
To me, the big six is simply awesome. I haven't even taken the engine cover off of my 330Ci motor...lol...double vanos...double the fun. ;) The thing runs like a watch however. But...too crappy of weather to even think about rolling it out. I am having serious car and nice weather withdrawl I am sure like all the other midwesterners are.
Hope all is well with you Robin and all my other homies stuck in the house because of the frightful weather.
George