Re: Update on my cylinder head problems

[BMWCCALA@xxxxxxx]

Mike -

A similar thing just happened to me last week ... I snapped the rocker arm 
for exhaust valve #4.  '88 535is, 140K miles.  

In my situation of 140K miles, only 55K of which have been with known 3500 
mile oil and filter changes (previous owners' maintenance history is sketchy, 
at best; significant varnish buildup), a complete inspection and valve job 
seems mandatory.

A few questions, if I might (hopefully not already answered in a previous 
post I missed) ...

Perhaps just semantics, but didn't a broken rocker arm result in more than 
what might generally be considered a 'miss'?  How long did this condition 
exist before teardown?   

How did a broken rocker arm contribute to oil seepage into the cylinder?  
(Combustion chamber vacuum pulling oil past valve seals?!?)

Are you convinced that rocker arm failure was the primary failure mode?  If 
so, how?  Evidence of lubrication problems, rocker arm to shaft seizure? 

How many miles on your car/engine/head?  Did you consider doing more than 
simply replacing the single broken rocker, as long as the head was off?

Thanks for any additional thoughts -- and best of luck with the repair.

Gerry O'Connor
Manhattan Beach, CA
BMW CCA - LA / SAE / NMA
'88 535is / '83 633CSi / '72 2002tii

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In bmw-digest V9 #2265, mike5635@domain.elided writes:

> To refresh, I have a 1990 535i.
> 
> The car was missing, and oil was seeping into the #1
> cylinder.
> 
> Head was pulled to find a broken rocker arm on #1
> intake!  I took the head to Ben Thongsai in Chicago
> this morning, who quickly swapped out the broken
> rocker for a good one.  Head going back on this
> afternoon.
> 
> Interesting note:  Ben said that, while not really
> common, rocker arms do break (altho usually the
> exhaust side).  When they do, the engine will miss,
> and oil will be sucked into the cylinder.  So, if your
> engine starts missing, oil gets into cylinder, and you
> can't figure it out, it just might be a rocker arm!
> 
> Michael in Chicago 

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