Chain Tensioners etc.

["Tom Brown" <tbrown@xxxxxxxxxxx>]

Andern:

The chain tensioner is an oil-fed device.   I've never had trouble with any 
of my 3 oilheads, but I don't think they're difficult to fix.  I've worked 
on the BMW car engine oil fed chain tensioners and they're easy.   Sometimes 
there's a bit of air in the sytem that doesn't work itself out and it's just 
a matter of clearing some dirt or sludge out of a vent hole.

BMW recommends 20/50 oil in these bikes or 15/50 synthetic.   Are you using 
these BMW oils?   I've used 15/50 Mobil 1 in Oilheads.  The bike works fine, 
but always makes more noise with Mobil 1.  Nowadays, I buy all my lube from 
the dealer simply because he's only 2 miles from my house and I want him to 
stay in business!   I'm not saying everyone needs to use BMW oil, just that 
it seems to quiet the engine down a bit.   I'm not an oil expert, but I 
think BMW puts some sort of addititive in specifically to quell some of 
these noises.  Other bike specific oils may do the same thing.

Transmission noises....If if makes a noise when you pull the clutch in, it's 
the throw-out bearing.  This is considered a clutch part and is usually 
replaced with a clutch job.  If it makes a noise when you let the clutch out 
in neutral, it's inside the trans and it'll be OK probably .   Use non-synth 
BMW transmission oil to minimize the noise.   Use their synthetic oil 
(really expensive, but you don't need a lot) to get better shifting. 
Honestly, it seems to work the best on 1100 transmissions, but it's slightly 
louder than non-synth.

VALVE CLEARANCE:   You're supposed to have 15mm clearance on intake valves 
and 30 mm on exhaust.   The bike should be dead cold when you make the 
adjustment.  Use not one, not two, but four seperate feeler gages, one for 
each intake and exhaust valve, when you measure a clearance.   Adjust one 
valve and it changes all the others.  Don't ask me why....but you'll be 
amazed if you try.

A really good valve adjustment assures that your throttle synch, to be done 
after the valves, will result in smoothness across the rev band and not just 
in one or two "sweet spots".

Hex head engines don't really require throttle synch adjustments if the 
valves are done properly.   I've got 25K on mine, have done every service 
and have never adjusted the throttles.   My bike is smoother than the day I 
took delivery with 8 miles on it.

The valve gap or clearance is needed because the valve stem gets hot and 
expands as the engine runs.  This makes the stem get longer.   There needs 
to be enough gap to allow for this growth.   The exhaust valve gets hotter 
than the intake, so it needs a bigger gap.

If you adjust a warm engine, the stems will already be expanded a 
little...but you won't know how much...so you can't compensate accurately.

Not enough clearance can cause a noise as the exhaust leaks through the 
valve during the actual ignition of fuel during the power cycle.  This is 
very destructive to valves, valve seats etc.   It sounds a little like the 
pinging sound you here when there is a leak in an exhaust manifold on a car.

Excess valve clearance won't damage the engine, but will reduce engine power 
and cause rattly metallic noises in the cylinder head area.

Another item that can make noise is the rocker arm side-clearance.   It is 
supposed to be very small...It's in the book.   Basically, you loosen things 
and bang on this big block next to the rocker arm with a soft hammer and 
close up the gap, then retighten.   There is a spec, but it's almost too 
small to measure.   I've cured some valve noises doing this procedure. 
Check out www.ibmwr.org in the tech section for this procedure.

Allen: I've never heard of a rod bearing going out on an oilhead.    I'm not 
saying it couldn't happen, but it's probably one of these other noises. 
1100 engines and drivelines make a lot of odd mechanical noises.   They're 
harmless.  Part of the fun of them is learning to ride them in a way that 
makes nice mechanical music.    Very chermin!

Unless you've run the thing out of oil or something, I would guess that the 
noises you describe at start-up are chain tensioner related.  You 
description sounds exactly like the noises my R1100RT made at start-up.

The high-temp increase in mechanical noise is caused simply because  the oil 
is thinner and the rocker bearings are being filled with thinner, hotter oil 
that runs out of the bearings quicker so they have more room to bang around. 
You notice this especially at idle because a lot less oil is being pumped at 
low engine speeds.

Another part of the cause for the noise is the valvetrain's proximity to the 
outside of the bike.  With a more conventional bike,  the valves are buried 
under the gas tank where it's more difficult to hear them from the rider's 
position.

This BMW system of long chains, rocker arms, pushrods and solid lifters is 
not the quietest, but it's very easy to adjust.  The nice proximity of the 
valves to the mechanic is another big plus.   I enjoy working on my boxer. 
I don't know if I could say that about other engine configurations.

-TB



On Mar 5, 2007, at 10:04 PM, Andren Appelquest wrote:

> The chain tensioning components of the oil pressure chain
> tensioning (2002 R1150RT) system are getting louder. It's not just
> at startup but lasts the entire ride (50-600 mi) and changes volume
> as a function of no correlatible variable that I can see.

I always assumed that a noise coming from my '94 R1100 engine was a
rod bearing starting to go.
It's a deep clunk sound, in synch with engine rpm, loudest at startup
(for a few revs before the oil pump makes pressure) and when oil is
thin (hot days, older oil)...  almost imperceptable when the engine
is under load with cold/new oil. Sounds a lot like the rod bearing
that failed on my 1976 90S, except that it's barely gotten any worse
in the 20,000 miles I've ridden this bike. The owner before me lugged
the engine, so I guessed rod bearing long ago and just started
monitoring the sound. I'm surprised at how little it's changed over
the miles.

Reading Andren's question, now, I wonder if my clunking could be a
"normal" sound from a chain tensioning mechanism. I guess it sounds
_a little_ like some noisy chains I've known over the years (Honda
small 4s, 16v Saab)

Can anyone with more oilhead experience help me know how to discern
the cause of my clunk?

Thanks,
Allen