Cam chain tensioner - failure symptoms, replacement guidlines

[pwillikers]

Vehicle: 2011 R1200RT (Model: K26, 0440), ~54K miles.

 

Good evening,

Over the past several months, my RT has started making a new engine sound.  I suspect it's related to the valve train, perhaps the cam chain tensioner.  I know it is nearly impossible to diagnose an issue given a verbal description of a sound but none the less, I persist.  :-)  I tried to record it but the recording couldn't capture the noise.

 

• It is most audible at approximately 2.5K RPM under very mild acceleration, deceleration and steady state throttle. 
• It's more prominent on the left side. (Or that could be my imagination; it's very hard to tell.)
• It originates towards the front of the engine.
• The frequency of the noise increases with engine RPM.
• It is present with the clutch both engaged and disengaged.
• There is no perceptible increase in vibration anywhere.
• It sounds almost as though a body panel is rattling against itself.  Attempting to rule this out, I've thumped and bumped around the body panels but have been unable to reproduce the sound.  I've removed and reinstalled all body panels.  They are tight and properly aligned.
• I inspected the alternator and the alternator belt.  Both seem in perfect order.

 

Do these symptoms sound like a cam chain tensioner loosing its ability to tension?

 

I've researched replacing the cam chain tensioner and this is most likely the path on which I'll proceed.

 

Is there an upgraded tensioner to be had or just replace with the OEM?

 

When replacing the tensioner, there exists conflicting guidance on whether or not the cams need to be aligned, as per a valve adjustment, whether the "stopper" needs to be removed (what is a stopper anyway?  see attached image) or whether the cam chain "guide rail" needs to be supported, as per the BMW special tool for this purpose.

 

Or, is it OK to just go ahead and replace the tensioner without regard to the above considerations?

 

Thank you for your consideration.

 

 

 

 

[MikeB60]

I've replaced a few cam chain tensioners on BMWs most recently on my 1600 but also on my 2011 RT.  The reason for replacing the cam chain tensioner on both bikes was a noise at startup. My hearing sucks (retired infantryman) so I doubt I would hear any noise at speed.

 

When I replaced the left cam chain tensioner on the camhead, I just pulled out the old one and replaced with the new one.  No issues.

[Boxflyer]

I'm sure there are some of the updated Cam Chain Tensioners here for the LH side....like 3 of the 4 rows are for the LH side!

 

The stopper is a device to help transfer impact energy from the somewhat fragile Valve Cover to the structure of the cylinder head.  Kinda like backing up the valve cover so it doesn't behave like an egg shell when there is a hit with the ground.

Like Mike says, you can remove/replace the Cam Chain Tensioners as a stand alone procedure.   

Brad

 

[pwillikers]

Brad, Quite the collection.  Are those all yours?

 

Is there any logic in replacing both the right and left tensioners at the same time or is the left one, as your count would suggest, usually the faulty one?

 

 

[Boxflyer]

Yes, these are just some of my Cam Chain Tensioners...

I really only wanted the RH CCT, but when I got some of them, these LH CCT's were included.

Some of these LH CCT's are the Updated version, and some are the less desirable older style.

 

I would not replace the RH CCT unless you have a serious issue with one...they are pretty reliable, and easy to remove to inspect.

 

These are used to make the DIY CCT for the WetHead/ShiftHead series of bikes...I've made about 75 of them so far.

I also use them to make direct reading Oil Pressure Gauges to assist in troubleshooting Oil pump/oil pressure relief valve issues, and to see if Chain noise is a problem caused by malfunctioning CCT's, or play in the Axle shaft of the Cam Chain Sprocket drive on WetHead's mostly.  The last picture is a Direct Reading Gauge on the R1200 CamHead .

      

 

I also make stainless steel sleeved front axle spacers for the HexHead/CamHead R1200's

 

Here are some custom K1600 Cam Bearing Bridge hold-down bolts to assist in uniformly removing/installing the Cams during a K1600 Valve Bucket change.

  

 

Here is a DIY TDC Locking Pin I made for the HexHead/CamHead as well...I like making TOOLS!

  

[pwillikers]

Based on the new engine noises described in the first post,  I felt it prudent to replace the left cam chain tensioner.  I purchased and installed a replacement from Euro Motoelectrics.  The existing one and the new one have 15mm bolt heads, so both are newer versions (the older ones have 17mm heads).

 

After removing the old one I compared lengths.  The free length of the replacement is about 12mm longer which would suggest the spring in the old one is fatigued at ~55K mi.  Good I'm replacing it.

 

When performing the replacement, I decided to take a conservative approach and align the cams in their valve_clearance_check_position to maximize cam chain slack and minimize required spring preload.

 

 

I was surprised to find the cam chain tensioner bolt quite loose.  I had to finagle a bit to remove the old tensioner.  There is very little clearance to remove it once loose. 

 

I had to finagle a bit more on installation of the new one in order to compress the tensioner spring enough to catch the threads of the tensioner body in the engine block.  I levered with a big screw driver on top of the bolt head while simultaneously turning the tensioner body with a wrench.  Once the threads were started, the rest was straight forward.  I strongly suggest a 15mm box end ratchet wrench for this procedure.

 

 

The replacement happily in place AND initial observations indicate this upgrade has quieted down the offensive racket.  :-)