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E34 (1989 - 1995)

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  #1  
Old 09-26-2010, 10:59 AM
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Radian Radian is offline
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Mein Auto: '91 535i 5-spd
M30 Valve train noise...gone forever.

When I replaced the head gasket on the M30 I bought a replacement head from Bavarian Auto Recyclers. After installing the head onto the motor, I proceeded to adjust the rocker arm clearance per the Bentley manual (which is straight from the factory BMW manual FYI).

Imagine my surprise when I fired it up for the first time in over a year and the valve train sounded like @$$. The fully reconditioned head sounded worse than a neglected mini-van motor. The #2 rockers were down-right dreadful sounding, and you could tell it was throwing the cylinder compression balance off, because the engine would hang a bit before settling back down to idle when when you gave the throttle a blip. Some people pawn it off saying that all BMW's have a tick to them. The $44,000 car would have never left the showroom floor sounding like that.

So I researched a little, and sure enough on worn-in heads, the ends of the valve stems get dimpled from the rocker arm eccentrics and lead to a false reading when you stick the feeler gauge in there. You end up with more gap than you think you've set.

I had to re-adjust my valves...again. So leaving nothing to chance this time. I bought new eccentrics. (about $70 from Pelican). I read online that new nuts should be considered because after time they loose their self-locking ability. There is no self-locking feature to the OEM clamping nuts. I bought new nuts and washers, and they thread onto the bolts like any other plain-jane fastener. This means the torque applied to the nut is an absolute key player to holding things in place. Leaving nothing to chance again, I bought some light-duty thread locker (Loctite 222) to supplement my torque wrench.

After replacing each individual eccentric, I reset the valve clearances. This time I used my feeler gauge in between the cam lobe and the rocker arm pad (which is a heck of a lot easier BTY). I used .009" because when you factor in the leverage ratio of 1.298, you'll end up with a clearance on the other end of .01168". That's a hair short of .012 and fine by me (the older M30's ran even tighter clearances from the factory BTY). I set proper torque on the nuts by using another technique I've picked up. I used a 10mm combination wrench as an extension. The open end fits a 3/8" drive snug enough to apply the correct force. You have to use the extension formula to figure the reduced setting on the torque wrench just the same, but using the combination wrench saves having to hunt down yet another "special tool"to get the job done.

I buttoned everything down, fired it up. Now that's how the engine is supposed to sound. The valve train is so quiet, the only thing you can hear is the tiny clicks from the fuel injectors. DONE.
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  #2  
Old 09-26-2010, 10:59 PM
JMI JMI is offline
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Mein Auto: 1989 535i
Radian,

Read your post with great interest. I saw a similar post some where that had the same results. My valves make a lot of noise and I had been considering doing the same thing.

You found you did not need new adjusting bolts?

Think I'm going to order the same stuff as you did but with the bolts also.

Jim
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  #3  
Old 09-27-2010, 06:36 AM
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Radian Radian is offline
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Mein Auto: '91 535i 5-spd
Jim,

Because this was going to be the second time I adjusted the clearances, I already knew my bolts were good. Mechanically, they are a non-wear item. Once adjusted, and the nut is torqued onto the bolt, the majority of the load from the eccentric passes directly to rocker arm. Odds are certainly in your favor that your bolts, nuts, and washers are still good so long as a previous mechanic didn't jack them up some how.

New bolts, on the other hand, are only another $20, nuts and washers even less. If you decide to order them, you'll still be under $100 total for the job.

If you have the Bentley manual, the only additional information you'll need to replace the eccentrics is this blurb from the factory BMW manual: "Install the eccentric into the rocker arm with the the adjustment bore facing away from the cam, thickest portion down."

Give yourself plenty of time to do things correctly. I took all afternoon, then let the car sit overnight to let the Loctite cure. The procedure reads very similar to a typical valve clearance adjustment:

-Put the car in Neutral and set the parking brake.
-Index the engine (or look for a cam lobe that's pointed down already and start there)
-Carefully remove the nut
-Carefully remove the washer
-Remove the bolt (I had one stubborn one I had to gently pop out with channel locks)
-Pop out the eccentric
-Wash the bolt in brake cleaner to clean the threads for the loctite
-Insert the new eccentric
-Insert the bolt, ensuring that it faces the correct way and mates firmly in its locking relief
-Carefully place the washer onto the bolt with needle nose pliers
-Place a drop of thread locker
-Thread on the nut
-Insert feeler gauge between pad and cam lobe
-Adjust and hold the eccentric (bent piece of coat hanger works nicely)
-Tighten down the nut, torque to 7 ft-lb
-Remove the feeler gauge
-Move on to the next rocker arm in order, index the engine if necessary.

Cheers,
Radian
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  #4  
Old 09-27-2010, 02:15 PM
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BMR_LVR BMR_LVR is offline
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Mein Auto: 1992 525i
Great write up Radian. Still glad I have the M50 with the hydraulic lifters though
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It's Deja Poo - as in, I've heard this **** before.
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  #5  
Old 09-21-2012, 11:55 AM
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Radian Radian is offline
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Mein Auto: '91 535i 5-spd
Just performed a recent 30K clearance adjustment / check and I'd like to stress something...

Don't mistaken the racket of the fuel injectors for perceived valve train noise.

I think it needs to be brought to the attention of most M30 owners that are trying to chase down "valve noise" just how loud high-mileage injectors can be. They can be down-right obnoxious.

However embarrassing mine are, I must say, I'm simply impressed at just how much noise they can make and still be perfectly functional. Their symphony of racket dominates over all the other engine noises.

See for yourself by watching the video below. Take notice of the pitch of the sound. A nice clean *snap*. Where-as the noise from too much valve stem / rocker clearance is lower in pitch. Tap the valve cover with you're knuckle a couple of times to hear what I'm talking about.



If you have a doubt about the origin of a suspected noise, take a listen using a mechanic's stethoscope or long screwdriver.

PS - Loctite 222 is the bomb. Provides just the right amount of running torque for those adjusting nuts.
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  #6  
Old 09-21-2012, 01:29 PM
haolibird haolibird is offline
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Location: san diego
 
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Mein Auto: E39 540i, E39 M5, E34 535
Radian,

Great write-up!
Thanks.

My valves are due, as there is 140k on the clock, 20k has gone by since I adjusted.
Not to mention they're louder than hell.
I will follow your advice, and replace the eccentric.
I especially like the "cam lobe/rocker" method.

Thanks again!
Tom
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  #7  
Old 09-23-2012, 09:43 AM
paperplane94 paperplane94 is offline
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Mein Auto: 1989 525i M20B25
Does anyone know how to calculate the "cam lobe/rocker" difference for the M20?
My valve stems have a valley in them.
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  #8  
Old 09-23-2012, 04:14 PM
snowsled7 snowsled7 is offline
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Location: SW Mountains
 
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The only thing I have to ad to Radians write up is that a small, long handle allen wrench works well for holding the eccentric. My car was noisy when I bought it last spring. I let it cool overnight, spent three hours setting the cam/rocker side. Nothing left but injector noise @ 160k miles.
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  #9  
Old 09-24-2012, 12:55 AM
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_Ethrty-Andy_ _Ethrty-Andy_ is offline
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Quote:
Originally Posted by BMR_LVR View Post
Great write up Radian. Still glad I have the M50 with the hydraulic lifters though
gah i hate those. my M40 is the same setup as the M50, bit mine is very ticky, but at $300 a piece to replace, its cheaper to put a new M40 in when the is one becomes unusable
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