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cam chain tensioners

hendrik

New member
I have a 04 1150 GSA with 25k Should I be concerned about this cam chain tensioner thing? What are the symptoms?
 
Noise on startup when cold (overnight) is the most common. I guess in certain cases over time it beats the chain guide to the point of breaking. Left side is the one that makes the noise. It is on top behind the throttle. Parts are about $130 right now. I have replaced mine. There is no more noise (mine was a little noisy on startup before)
 
Noise on startup when cold (overnight) is the most common. I guess in certain cases over time it beats the chain guide to the point of breaking. Left side is the one that makes the noise. It is on top behind the throttle. Parts are about $130 right now. I have replaced mine. There is no more noise (mine was a little noisy on startup before)

Parts are less than $90 from Rubber Chicken Racing.
 
Parts are less than $90 from Rubber Chicken Racing.

If you wear ear plugs, you might not hear the noise. Also, if you start up cold and ride away you may not ever hear the sound.

To truely test for the sound you need a helper to start the bike. A rally or tech day would be a good place to have someone check. With your millage it is unlikely you need to do anything. Normally, only high millage bikes have issues with cam chain tensioners. To test for a cam chain tensioner failure you or your helper has to listen for the sound on the cyclinder head after the bike is warmed up. The flapping happens when oil pressure has not built up to the nominal rate. So, it is probably from 0-30 seconds after the bike is started. After that the flapping will go away and the bike should sound like a sewing machine. You will have to let the bike sit for at least 10-30 seconds for the oil pressure to drop back to zero after turning it off. You need to listen to both cyclinder heads, but the left side seems to fail more than the right for some reason it seems.

Also, according to Chris Harris of 'affordable BMW repair' in NH cam chain tensioners don't fail until about 80K.
I had 83K on my bike when mine failed.
 
I have a 04 1150 GSA with 25k Should I be concerned about this cam chain tensioner thing? What are the symptoms?

Symptoms are a racket coming from the left side of your motor on start up from cold (or after sitting for a hour or so which allows oil to drain out of the left-side tensioner) which disappears after a couple of seconds. I replaced mine at 30,000 kilometers. Do as Bikerfish has suggested and you'll be a happy camper/rider/person.
 
If you wear ear plugs, you might not hear the noise. Also, if you start up cold and ride away you may not ever hear the sound.

To truely test for the sound you need a helper to start the bike. A rally or tech day would be a good place to have someone check. With your millage it is unlikely you need to do anything. Normally, only high millage bikes have issues with cam chain tensioners. To test for a cam chain tensioner failure you or your helper has to listen for the sound on the cyclinder head after the bike is warmed up. The flapping happens when oil pressure has not built up to the nominal rate. So, it is probably from 0-30 seconds after the bike is started. After that the flapping will go away and the bike should sound like a sewing machine. You will have to let the bike sit for at least 10-30 seconds for the oil pressure to drop back to zero after turning it off. You need to listen to both cyclinder heads, but the left side seems to fail more than the right for some reason it seems.

Also, according to Chris Harris of 'affordable BMW repair' in NH cam chain tensioners don't fail until about 80K.
I had 83K on my bike when mine failed.

I'm gonna go out on a limb here and say that if the chain skips just one link, much less fail totally, it'll cost way more than $90.
 
I'm gonna go out on a limb here and say that if the chain skips just one link, much less fail totally, it'll cost way more than $90.

Thanks for the info. I just changed the oil and filter so I guess thats when it should of been the loudest being the oil filter was empty. There was no noise so I'm probably ok for now. I plan to do clutch splines at 50k maybe I'll do tensioners then.
 
You may already have the new style - check the head size.
Don't wait
There are those that believe that the old style tensioners contribute to the chain guides breaking and that is real bad news. Replace if you have the old style.
 
You may already have the new style - check the head size.
Don't wait
There are those that believe that the old style tensioners contribute to the chain guides breaking and that is real bad news. Replace if you have the old style.

Head size? What do you mean exactly.
 
When i first scored my 02 1150 the start up noise was terribal, sounded like a main bearing in an old chevy. it was that bad, one of the first things i did was change out cam chain tensioner. quit as a sewing machine now. i would recomend it be done even if start up noise minimal. its not that hard to do once you get the throttle body ota the way. if i remember correctly parts wer 80 buks.
 
Original part has 17mm head size, updated one has 15mm head size (top the the tensioner hex)

Indeed - the housing of the original tensioner took a 17mm wrench to install and tighten (or remove) the tensioner. The revised tensioner housing takes a smaller 15mm wrench to install and tighten (or remove).

So if a 15mm wrench fits it is the new style. If a 17mm wrench fits it is an old style.
 
I believe there may be at least two "new" versions with 15 mm hex, so if so this isn't evidence the latest version is installed.

I post this to learn more.
 
I've done a few now and all the updated one piece plungers (no loose spring) will only fit into the 15mm head.


This picture is courtesy of ADV riders - note the hex size difference
 

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Don't wait
There are those that believe that the old style tensioners contribute to the chain guides breaking and that is real bad news. Replace if you have the old style.

The LHS cam chain is being improperly tensioned with original tensioner, it's just a question of how long one can get away with it.
That said, OP can probably wait till 50k maintenance.

My LHS tensioner failed at about 130k miles. The plastic chain guides had been worn through, then shattered, then the chain jumped off the sprocket and kinked.

Some speculation on causes, perhaps real experts will comment:
-the old LHS tensioner (17mm bolt head, 1998-2006?) failed due to clogged oil port, causing the piston to stick instead of pushing down on the upper chain guide.
-the RHS tensioner never (?) fails, because its piston pushes UP and somehow the oil drains from it without problem.
-it's possible that frequent oil changes help prolong the original LHS tensioner, which depends on very clean oil.
 
The LHS cam chain is being improperly tensioned with original tensioner, it's just a question of how long one can get away with it.
That said, OP can probably wait till 50k maintenance.

My LHS tensioner failed at about 130k miles. The plastic chain guides had been worn through, then shattered, then the chain jumped off the sprocket and kinked.

Some speculation on causes, perhaps real experts will comment:
-the old LHS tensioner (17mm bolt head, 1998-2006?) failed due to clogged oil port, causing the piston to stick instead of pushing down on the upper chain guide.
-the RHS tensioner never (?) fails, because its piston pushes UP and somehow the oil drains from it without problem.
-it's possible that frequent oil changes help prolong the original LHS tensioner, which depends on very clean oil.

Thank you for the explanation.

I have read that the Left one drains down on a hot shut off. When the bike is started the next time there is little tension until the oil pressure builds.
The Right one does not drain down because it is inverted under the cylinder.
 
Last edited:
..I have read that the Left one drains down on a hot shut off. When the bike is started the next time there is little tension until the oil pressure builds.
The Right one does not drain down because it is inverted under the cylinder.

That makes much more sense, thanks.
 
That makes much more sense, thanks.

Yes it does. Look at those photos of the old and new styles.

On the left side the old style "cylinder" or housing screws down from the top and the piston sticks up from the bottom, giving gravity the perfect opportunity to suck the oil out of the upside-down cylinder.

Notice that the new style has an entire tensioner similar to those on the F650 and F800 which sticks up inside the new style housing. And not that the tensioner cylinder goes in down and the piston sticks up ito the housing - keeping the oil inside the tensioner, inside the housing screwed down from the top.
 
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