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Rubber Damper??


Dave_Armstrong

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Dave_Armstrong

Greetings,

 

Today I began my BMW maintenance program, such that it is. Did an oil and filter change, went OK, except I forgot to fill the filter before installing. Everything seems to be OK.

 

Did the valves, and removed the tupperware for the first time on an 1150RT. Went well. I got the rocker arm covers off and did my adjustment and everything went OK. As I was putting the right rocker arm cover back on and fiddling around, a small rubber block fell into my drip pan. It was black rubber about 1" X 1" and was split and sort of molded. I could not see where it came from or an obvious place for it to fit.

 

After looking through my maintenance book, I found an exploded view with a part called 'Rubber Damper'. I finally found a picture of it installed and appeared to fit around the forward lower rocker arm assembly bolt. It fit nicely when pushed into place. The molded part fit around the bolt and an adjacent casting.

 

My question is,,,,what does it do and is it needed? I'm certain others have knocked it loose and just discarded the part. I did not remove the left cover to see if it was in place, next valve adjust I will look.

 

I'm just curious, and thanks,,,,,Dave

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Little_Brit

Dave,

 

It's almost certainly a noise reducing damper. Having the noisiest part of the engine, the rocker box, pointing out straight at a noise meter is not the easiest way to meet stringent noise limits. Ignoring the marketing departments take on oil cooled cylinder heads the main purpose of the oil filled rocker box is to reduce noise. On start up you get a few seconds of really noisey tappet rattle until the rocker box fills with oil and damps it out.

 

Derek Brown

 

R850R

Yamaha Tmax

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ShovelStrokeEd

Yep, it's a noise damper but the noise Derek describes is not coming from tappets, it is, rather, the cam chain which has a hydraulic tensioner driven by engine oil pressure. Until the oil pressure comes up to specification, the cam chain will rattle around a bit.

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I agree with most of this post, But I do question the inference that the valve cover "fills" with oil... I believe more acurately that it is a wash in oil being sprayed about from normal oil circulation. Not filled like a glass of water...

 

 

I think tthe oil drains back to the crank case about as fast as it is pumped in there..

 

More opinons please?

 

BK

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Little_Brit

My understanding is that it is exactly like your glass of water, full. More full than empty at any rate!

 

Derek Brown

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Not filled like a glass of water...

 

 

More opinons please?

 

Our bikes are affectionally called "oil heads", not oil valve covers: not only does oil not fill the valve cover area, it isn't sprayed there either. Oil is preasurely (what a word !) applied to exhaust port (contained in head, not valve cover) for cooling effects.

As to the rubber piece in each valve cover, my Haynes says (the manual, not the undies) some oilheads have it some don't; my '98 RT has it.

 

Wooster

 

mean spirited cooks beat eggs and whip cream

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Dave_Armstrong

Thanks to all the replies. If the left rocker box is without the damper, it sounds like it won't matter much. With my angst eased, I'm off for a week on the bike.

 

Thanks for the thoughtful replies.

 

Regards,,,,Dave

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