Timing chain tensioner questions

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by jamesbrown, Apr 19, 2010.

  1. jamesbrown

    jamesbrown Lefty tighty.

    Joined:
    Nov 21, 2007
    Oddometer:
    6,413
    Location:
    Gone
    Hi guys,

    06 950 Adv. I've had a noisy engine since day dot, specifically intermittent camchain noise throughout the rev range without low oil pressure. I'm familiar with the threads on camchain noise by Kamanya and uk_mouse.

    I replaced the hydraulic tensioner element on the rear cylinder about 8 months ago and that appeared to resolve the issue. However, the camchain noise has been getting louder again recently. It remains somewhat intermittent, but has become gradually more frequent, more persistent, and louder. It occurs throughout the rev range and is not associated with low oil pressure. The same thing happened before I replaced the tensioner element last year.

    Now I'm wondering why the hydraulic tensioner should fail so quickly. The spring shouldn't fail in eight months of use, surely? Could this be associated with an elongated timing chain? Could something else promote the failure of the tensioner element? I didn't actually measure the tensioner element when I removed it last time, but the replacement did resolve the problem.

    Also, the tensioner element is held in place by screw #60036008000. I see reference to a longer screw here with p/n #60036008100

    http://www.advrider.com/forums/showthread.php?t=359792

    But I cannot find this p/n in any of the usual stores, which is weird.

    One last question: if I decide to simply replace the tensioner element again, rather than digging deeper, is there any reason why the tensioner element shouldn't simply be switched out? The only reason to lock the rear to TDC would be to measure preload, right?

    Thanks guys.

    James
    #1
  2. DirtyADV

    DirtyADV Long timer

    Joined:
    Jan 13, 2007
    Oddometer:
    3,072
    Location:
    SWEDEN, SkellefteƄ
    I can find both these parts, wonder what the difference is ...the later just a little longer? Should be alot longer since it costs twice as much as the original.

    Anyone know how much longer? Possible to just add a spacer on the original? Or will that take a quick trip around the engine trashing everything it makes contact with?

    Working on a service on my -04 and last i measured the wear on the cam chain seems to be close to the limit but hopefully a longer plug holding it might be enough for the summer and maybe look further into the engine next winter.

    /Johan
    #2
  3. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    Jamesbrown: how many miles has your 950 done?

    Last summer my 2004 950 ADV (45,000 km/28,000 miles) started to clatter for a second or two directly after starting. I changed the oil and filter (Motorex 10W/50, as always), but the start-up clatter continued. Never any clatter during running; only upon start-up at any time.

    This winter (at 51,000 km / 32,000 miles). I replaced both the hydraulic cam-chain tensioners (CCTs) and the clatter disappeared. And so far, after many starts but not many miles, it's stayed good.

    To test, I reinstalled the old CCTs front-in-rear and rear-in-front, and the clatter was worse than it ever was. By reinstalling one good (new) CCT at a time I found that the CCT that was in the rear cylinder was the one at fault. It was also worse in the front than it was in the rear. Maybe because it's up-side-down, and therefore drains down more easily (quickly) than it did when upright when installed in the rear. If this is correct, it suggests that the oil is draining out via the ball-valve, rather than between the plunger and the casting of the CCT.

    However, if your cam-chain is noisy while the engine is running, I think that it is more likely to be an over-long cam-chain, or worn cam-chain guides. I see no reason why the CCT should get shorter as long as oil is supplied at the correct pressure.

    My KTM dealer did offer me the longer CCT plugs (60036008100, price US$ 19 against the original item: 60036008000 at US$8!). I don't know how much longer they are (sorry). The part is not listed on their on-line shop.

    This long plug will enable us to get more life out of our cam-chains and guides, so in this context, they offer good value for money. Maybe.

    I never locked the engine with the locking bolt while removing the CCTs. When measuring, I just made sure that the engine last turned in the correct direction by turning the flywheel, using the 14 mm key, in the CCW direction. The cam-chain will not jump on the cams when the CCTs are removed.
    #3
  4. DirtyADV

    DirtyADV Long timer

    Joined:
    Jan 13, 2007
    Oddometer:
    3,072
    Location:
    SWEDEN, SkellefteƄ
    I have ~50 000kms on mine, some clattering on startup, and sounds like its chewing rocks all the time on idle and with revs, have had a hard engine sound since i bought it with 3500kms.

    Never heard the clatter of death that it has when first starting up after an oilchange.

    Think it says when bolting the plug in u should have 6-11mm left when u start feeling that the CCT starts beeing compressed.

    /Johan
    #4
  5. DeeGee

    DeeGee I'm a Yorkshireman thanoz

    Joined:
    Jan 2, 2008
    Oddometer:
    1,889
    Location:
    Up North In The UK!
    To fit the CCT is it a difficult job? How long (average) would it take to do?
    I'm not sure they are fitted to my bike as I've only had it a few months, how do I tell if they're fitted or not?

    Cheers
    #5
  6. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    Hi Gav

    Your bike has CCTs. If they wear out, they can cause a brief clatter just after starting.

    If you have this one- or two-second clatter it may or may not be causing damage.

    Cheers, Rupert
    #6
  7. jamesbrown

    jamesbrown Lefty tighty.

    Joined:
    Nov 21, 2007
    Oddometer:
    6,413
    Location:
    Gone
    Thanks guys.

    Dirty950: I'm thinking along the same lines of replacing the (probably) faulty CCT(s) now and digging deeper next winter. The longer bolt is, according to the thread I linked, 5mm longer. I just can't find it in an online store :dunno

    RedRupert: the bike is still relatively low mileage at <10k miles. I wouldn't have expected worn guides or elongated chains by now, but I don't know(?) Everything should be in alignment; no major engine work has been done on the bike. Also, while they are hydraulically operated, I think the issue here is that the (spring in the?) tensioner element is becoming too compressed over time, which is causing problems even at normal operating pressure (i.e. after start-up). Actually, I wouldn't view a brief start-up clatter as problematic (it is to be expected, I think). I should have measured the faulty element when I removed it last time. I know uk_mouse did these measurements and reported in detail on the H.O.W.

    DeeGee: yes, your bike has them. Replacement alone should be very quick for the rear cylinder. You need to remove the oil tank to access the front cylinder.
    #7
  8. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    This is how I see it. I could be wrong, though:

    The spring-and-ball valve is there to stop the hydraulic CCTs collapsing/draining down, especially while the engine is not running. While running, the oil pressure pumps the CCTs up, which keeps tension upon the chain. If there is clatter, it must mean that the chain is loose:

    A) because it's beyond a weak (leaky) CCT's ability to apply enough pressure, or

    B) the chain/guides are worn/stretched so much so that the CCT is not long enough to tension the chain properly.

    A new non-leaky CCT will put first right; longer pugs will put the second right.


    I don't think it's very good to have clatter at any time - metal hitting metal is never desirable. Is it? That's why I went to the expense and trouble of getting rid of the start-up clatter.
    #8
  9. jamesbrown

    jamesbrown Lefty tighty.

    Joined:
    Nov 21, 2007
    Oddometer:
    6,413
    Location:
    Gone
    Yes, agreed. No contact is desirable, but it seems that a small amount on start-up is symptomatic of the design. For now, I think I'll just measure the preload and fit new CCT(s) (unless the preload is out, in which case I'll have to dig deeper) and fit the longer screws (if I can get them :lol3 ). If it does turn out to be the CCT(s) again, I'm still a little stumped as to why they would wear so quickly; ultimately you could be right about the chain/guides being worn. The preload was OK before, but it might not be now....anyway, thanks again :thumb
    #9
  10. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    Why don't you order one long plug - they are half the price of the CCTs? You can try the long plug in one cylinder at a time - I think it's highly unlikely that both cylinders are responsible for your noise - usually one will wear before the other.

    You can order the long plug by part number from any KTM dealer.

    It will not be wasted money, as you will need one (two, actually) sooner or later. as it is a fact that cam-chains wear eventually. :cry
    #10
  11. kamanya

    kamanya Andrew to most

    Joined:
    Jun 3, 2004
    Oddometer:
    1,447
    Location:
    Southern Tip of Africa
    Hi,

    I am sure the clatter is not metal on metal.

    There are two chain guides per cylinder. One has the CCT pushing on it, the other is fixed on the drive side of the cam chain. The sound is generated by the static tensioner guide being slapped by the cam chain as a result of not enough chain tension on the CCT side guide. At low revs, as the cam goes past TDC the valve springs accelerate the cam to the point of removing tension on the drive side of the chain. The chain has some slack that once the engine has caught back up, it whacks the static guide as it is pulled tight.

    Once the CCT's have come up to operating pressure the symptoms stop.

    I am sure the CCT's once they get past a certain point of wear they "leak" more than designed and cause the clatter symptoms. It would be interesting to find out what causes the "wear" - certain oil? Debris abrasion? Tolerance issues?

    My bike since it's little hiccup has run well with no return of the symptoms. It's still not the most mechanically quietest bike but this is what it seems to just be. I have a 990S too that's almost silent in comparison but I am sure that it's just missing some clattery character.

    My 5c.
    #11
  12. DirtyADV

    DirtyADV Long timer

    Joined:
    Jan 13, 2007
    Oddometer:
    3,072
    Location:
    SWEDEN, SkellefteƄ
    Measured my tensioners today while checking the valves, they are very close to starting spec and nothing seems to have changed since i checked last 10 000 kms ago so guess ill leave them as they are.

    /Johan
    #12
  13. flytier

    flytier Refusing to grow up

    Joined:
    Jul 30, 2008
    Oddometer:
    87
    Location:
    Ozarks
    Just as a benchmark, my 08 990 has clattered intermittently on startup for about 1-2 seconds since new. I feel inherent in design. Back in the day all KTM's sounded like a box of rocks but no more, quiet and smooth for me(motorex 10-50)
    #13
  14. skuikka

    skuikka Adventurer

    Joined:
    Jun 23, 2009
    Oddometer:
    94
    Location:
    Finland
    Thanks for the idea. 38 degree celsius fever, bored, bike at reach, occasionally clattering cam chains, 32000 km.
    Opened first the front cylinder bolt, no oil dropped out. This means that there is room for the oil in the front cct to come out. The bike had been standing for a few days.
    Then I took the rear tensioner out and pumped both full of oil, squeeshed them against each other and the front gave up first, repeated a couple of times, and yes the front leaks more.
    This could mean that the front tensioner, which is facing downwards would wear faster because it gets much more start-ups while being empty, more movement>more wear.
    In the rear, the tensioner is placed so that it can not drain empty, because the hole is pointing up.
    I opened the front CCT, there is a ball-valve and a spring inside. Took me a while to find them from the living room :) There is no seals, just metal surfaces sealing the oil.
    When the oil-pump starts pushing pressure the CCT:s should tighten immediately, but if the front CCT has bled completely empty there is a bit of air inside, and the air has no route to get out because the in/out holes are in the lower end of the CCT. This would explain why the clattering sometimes lasts for a while after the bike has not been used for a while.
    #14
  15. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    My rear CCT was at fault. I installed the rear in the front and the symptoms were worse. I also tried one new CCT with the not-so-bad old one from the front, and it was OK.

    On the work-bench - when filled with oil, the bad rear CCT compresses more easily. The oil gets out between the body and the plunger, rather than via the ball-valve.

    The rear CCT had signs of wear on the outside of its body. I don't know how it came about. I'll go and check it more carefully.
    #15
  16. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK

    Interesting stuff. Plenty of fuel for thought.

    I think my clatter sounded too sharp to be a plastic cam-chain guide. Don't you think plastic and metal would be more dull sounding?
    #16
  17. skuikka

    skuikka Adventurer

    Joined:
    Jun 23, 2009
    Oddometer:
    94
    Location:
    Finland
    There goes my theory:)
    I put the more worn to the rear and bike was quiet at the start-up. I pre-filled the CCT:s. I'll leave the bike standing until the flue goes away and see then will it rattle.
    I didn't have leek in the ball-valve either, the oil came out as you said, between the body and the piston.
    If I understood correctly, the body is sealing the oil-pressure thats supposed to pressurize the tensioners so that it doesn't leak towards the chain and from there down to the sump.
    If you have scoring in the walls of the hole where the CCT stays, and also the CCT has grooves in the surface, and then you swich the CCT:s around, I would assume that you would end up having lower pressure in both CCT:s. Would sound logical. Maybe.
    #17
  18. jamesbrown

    jamesbrown Lefty tighty.

    Joined:
    Nov 21, 2007
    Oddometer:
    6,413
    Location:
    Gone
    Interesting posts.

    It was my rear CCT that went out first time and, based on the origin of the sound, I think it's the rear cylinder CCT again this time.

    It does sound like metal on metal, but I went for some time before diagnosing the problem last time, and there were next to zero metal shavings when I changed the oil....
    #18
  19. kamanya

    kamanya Andrew to most

    Joined:
    Jun 3, 2004
    Oddometer:
    1,447
    Location:
    Southern Tip of Africa
    It is very hard plastic and I feel that if it were metal on metal there would actually be less of a noise.

    It's precisely because its very hard plastic that it makes such a racket.

    I could find no wear on the chains at all. Although, as you can see on my thread on this topic, the chain ate into the locking screw and the balancer, but that noise when the balancers were hitting the chain was very distinct from the normal start-up clatter.
    #19
  20. RedRupert

    RedRupert Brit in the Soviet Union

    Joined:
    Jun 12, 2006
    Oddometer:
    635
    Location:
    Riga, Latvia / Bergerac, France / Colchester, UK
    This photo is of my bad rear CCT.

    Perhaps the band of wear is a clue? In the photo - about 4 mm wide and 16 mm from the chain-end of the CCT unit - it's not so obvious that it's a constant band in the photo, but it's easy to see that there is wear there. There was no such wear on the other good used (front) CCT that was quiet on start-up.

    Could it be that the CCT is draining down by 4 mm too much each time? The start-up clatter is the cam-chain (slapping the rail, kamanya) while the 4 mm is taken up? That movement each time has shown up on the CCT body.

    This bad CCT unit looks OK in other respects - It does not fall apart, as mentioned in the KTM Repair Manual. But could it be that the oil is seeping out from between the body and piston just a little too easily?

    Attached Files:

    #20