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E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 10-06-2005, 09:54 PM
Chris Ruper Chris Ruper is offline
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Location: Rockton, IL.
 
Join Date: Oct 2005
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Mein Auto: 1987 325i
Broken Rocker Arm - Probable Cause? (long)

Hey all,
I have a 1987 325i that I bought recently (3 weeks and 500 miles ago). Not sure exactly how many miles since it seems someone has put in a guage package from a 325e in it (low redline).

Anyways, I now have a broken rocker arm (#4, intake side) and I'm wondering if anyone has seen this problem before. A few things...

It "ticked" when I bought the car. I did a valve adjust on the car and that took care of most of the noise. I purposefully left them slightly loose (.011-.012") but the "play" was much less than before so they were much better. Still a slight "tick" but I was kinda figuring the "loose" valve clearance may still be causing the noise.

I drove the car for a week (50-60 miles/day) after the valve adjustment (ran fine the entire time). It actually ran slightly better....

Driving home one night (late) the engine just suddenly stopped making any ticking noise and the power was "lacking" on it. I kinda figured that it might be a bad plug or something and since it was 11:30 at night and running (albeit sluggishly), I'd drive it the 20 miles home....

I open it up the next morning and find a broken rocker arm (split right through the center of the rocker shaft hole). After some teardown to remove the head (check for damage) I found the following.....

Timing marks line up fine (the belt must not have slipped). The valves look good (I'm still in the process of taking the head apart). No damage has been done to the piston (no marks from a valve/piston interference problem). Someone has been into the engine before (missing one tab on the rotor hold-down and missing the pin and spring on the timing belt tensioner).

So..., any thoughts on what might have happened? Anyone else have a rocker arm broken but no other major damage? (I'm looking to narrow down a cause, if possible, so I can correct any problems).

Thanks for the help,
Chris
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  #2  
Old 10-20-2005, 01:57 AM
1986-325i 1986-325i is offline
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Location: 1986-325i
 
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Mein Auto: 1986-325i
Hey chris
I have the same problem in my car
broke to rocker arms, i think it was caused by over reving? it shouldnt of be because of your valve clearance adjustment as this wouldnt increase the the load on it or anything?
i think they must have casting faults or something.
It is in my friends car and we need help in this area.
How do u get the long shaft that holds all the rockers out? it like has a thread on one end or something and i cant figure out how you get it out? etc. any help here would be greatly appreciated!!!
I did a search and all to no avail.
From logan -New Zealand-
1986-325i

edit:
this is what causes this on our bmws
On all early single-cam, 4 cylinder and chain-driven, 6-cylinder engines the rocker arms are held in position by a tensioner spring. In high R.P.M. situations these springs permit the rocker to move laterally. Rocker arm failure is the result. Once the rocker leaves the valve stem contact area the rocker will bind against the retainer resulting in broken rocker arms. The BMP retainers will stop high R.P.M. rocker arm movement. The two-piece billet aluminum construction permits installation without cylinder head removal.

Can you still help with the original q?

Last edited by 1986-325i; 10-20-2005 at 03:03 AM.
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  #3  
Old 10-21-2005, 09:57 AM
99flhr 99flhr is offline
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Location: ohio
 
Join Date: Apr 2005
Posts: 1,100
Mein Auto: 00 Z3 2.8
Quote:
Originally Posted by Chris Ruper
Hey all,
I have a 1987 325i that I bought recently (3 weeks and 500 miles ago). Not sure exactly how many miles since it seems someone has put in a guage package from a 325e in it (low redline).
Chris
Maybe it is an "e" and somebody changed the badge?
Have you been observing the "e" redline or the "i"
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  #4  
Old 10-24-2005, 07:19 PM
1986-325i 1986-325i is offline
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Location: 1986-325i
 
Join Date: Oct 2005
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Mein Auto: 1986-325i
bump this sucker back up....
i need a hand as i said in the post, bout how do ya get the rocker arms out of the head of my car, i cant get that long shaft which they all pivot-on out?
please help a man out, i was wanting to put my new rockers in this weekend!
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  #5  
Old 10-24-2005, 08:03 PM
fporro fporro is offline
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Mein Auto: 87 325iC
there's slots at both ends,
remove the "key" from them,
remove any tension from all the other rockers by loosening eccentrics.
slide off some of the rockers from the valves,
tap the shaft out.

i did it with the head on the engine

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cheers,
Frank
e30 parts

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  #6  
Old 10-25-2005, 04:41 AM
SWISS SWISS is offline
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Mein Auto: E30 S52 / S52 M roady
You might need to replace the cam.When I had my head rebuilt the machinist said I need to replace the cam since I'm replacing the rockers. said the "pads" on the rockers are worn to the lobes on the cam said if I didn't it would be like putting worn brake pads on a new set of rotors
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  #7  
Old 10-30-2005, 01:28 AM
zadious zadious is offline
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Location: Pine Knot Kentucky
 
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Posts: 5
Mein Auto: 318i 735i
Exclamation broken springs here too...

we had a 1987 325is with the same problem #3 exhaust broke but snapped off at the tappet, on the rocker, we slid out the rod, and replaced the rocker easily, i think we had to take out the grilles and radiator to do the work in the car. never did figure what actually did the damage, replacement worked for 10,000 miles, then sold car. good luck.
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  #8  
Old 11-07-2005, 11:50 AM
Chris Ruper Chris Ruper is offline
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Location: Rockton, IL.
 
Join Date: Oct 2005
Posts: 2
Mein Auto: 1987 325i
Sorry it's been a while but it's taken me some time to get everything back together and considered "road worthy".

The problem as mentioned before was a broken rocker arm. Here's what happened....

The people before me didn't adjust the valves and so it had been running "loose" for some time. When you run these type of rockers "loose" they tend to create an odd wear pattern on them (they don't wear in the right places) and then the rocker arm and camshaft start wearing heavily.

Since these had been running like this for some time, the rocker arms had concave spots worn into the contact face (where it hits the cam) and the cam lobes had been worn severely (a nice groove worn through the top part of the lobe).

While these were run, the rocker arm would occasionally ride up onto the "normal" part of the cam lobe. When it would do this, the rocker arm would "drop" down into the groove worn into the cam, creating a momentary slack condition that is immediately removed when it hits the cam.

Essentially, this rocker arm snapped because it kept getting tension-release-tension again while opening the valve. Since there is such a large amount of force to open a valve, I'm sure the force put onto the rocker arm eventually caused it to snap the end of the arm off.

As for the engine itself, it has been identified as an "i" engine, but I have found a "mileage inconsistancy" in the car's records that indicate a new gage cluster was put in place (state records show a "drop" in the car's mileage during the registration process).

The lesson from this all? Don't run these engines with the valve adjustment very loose (believe me, they were LOOSE).

The cost for all this... $800 and three weekends. I replaced the cam, rockers arms (eccentrics, bolts and nuts), timing belt, accessory drive belts, head gasket set, cylinder bolts, distributor, cap, rotor, rotor mounting piece, misc. coolant and breather hoses plus a few other small items, nut and holders.

Needless to say, I shopped around.

Chris
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