DF 150s Clicking noise

[JKDeVine]

UPDATE: Thanks for feedback. Update is valve check showed valve clearances within tolerances. Not the source of ticking. Now focus on balancer chain and sprocket per discussion with Suzuki tech down south. Will inspect bearings and shaft while in there. About to take off powerhead. Looking at large bill and want to make sure we are not a fishing expedition. I have heard of issues with tensioner on timing chain causing ticking but not balancer chain. Anyone have any thoughts?

[RALKITE]

I have twin Johnson 2003 140’s so DF140.
1500hrs.
broke six inlet valve springs bent two valves.
replaced springs and valves and reassembled.
first ten minutes of on water test was perfect then sudden rattle and shut it down.
everything checked out but rattle/knock stayed.
rocker cover off and noticed cam chain very loose.
loose enough that chain is loose on reduction gear sprocket so at TDC I can rock crank back and forward and the produces the sound that seems to come from everywhere but when down looking at reduction gear it is coming from the loose chain and the crank gear and reduction gear.
removed cam chain tensioner which appears ok replaced and chain was tight again and no noise when rocking crank.

reassembled and started. First ten seconds no noise then back it comes.
so can someone please save me from this head F.

[redlowrey]

The only way the chain could be loose is if the tensioner plunger is not coming out and locking, keeping tension on the chain guide against the chain.
If you had a new chain, tensioner, and chain guide, the plunger would be lucky to come out more than five mm out of the housing.
If you look at the tensioner plunger, inside there is a spring and teeth cut into it so it will lock as it comes out of the housing keeping pressure on the chain guide
up against the chain so it will keep pressure against the chain even without oil pressure.

Surely you would have heard chain rattle on start up long before it got to the stage of jumping teeth and bending valves.
You did pull the plunger locker out of the tensioner.

[RALKITE]

The plunger has maybe 5teeth showing when chain is in tension but the distance it travels back before ratchet engagement is enough to slacken chain. I am assuming that oil pressure keeps it properly tensioned, but.
yesterday I lifted power head to try again and checked valve clearances and cam timing. Not issue.
however I did check that when loose there can be nearly six degrees of crank rotation to take up slack in cam chain.
I removed cam chain and driven gear, noise gone and crank feels perfect.
replaced it all noise back.
hold long screwdriver in to hold pressure on tensioner no noise no slack.
stripped down tensioner. Cleaned but no apparent issue.
At moment I am suspecting an oil pressure issue. Checked pressure bypass valve seems to be fine.
engine run with rocker cover off shows plenty oil getting around but is it getting to tensioner.
I’m thinking that this has no direct connection to initial failure but maybe to some dislodged shit going for a ride.

[Murray]

Could it be noisy injectors? Just a thought.

[redlowrey]

The plunger has maybe 5teeth showing when chain is in tension but the distance it travels back before ratchet engagement is enough to slacken chain. I am assuming that oil pressure keeps it properly tensioned, but.
yesterday I lifted power head to try again and checked valve clearances and cam timing. Not issue.
however I did check that when loose there can be nearly six degrees of crank rotation to take up slack in cam chain.
I removed cam chain and driven gear, noise gone and crank feels perfect.
replaced it all noise back.
hold long screwdriver in to hold pressure on tensioner no noise no slack.
stripped down tensioner. Cleaned but no apparent issue.
At moment I am suspecting an oil pressure issue. Checked pressure bypass valve seems to be fine.
engine run with rocker cover off shows plenty oil getting around but is it getting to tensioner.
I’m thinking that this has no direct connection to initial failure but maybe to some dislodged shit going for a ride.

Did you fit genuine chain, tensioner, and guide, because something does not sound right, the hole idea of the ratchet is to have no play in the chain. As it stretches and wears the plunger comes out of the housing keeping zero clearance against the chain and guide, oil pressure puts enough pressure on the plunger to lock in on the teeth.
Even if the tensioner had no ratchet there is no way a new chain would be loose enough to jump teeth, but a badly stretched old chain and a drop in oil pressure would let the plunger go back into the housing making the chain very loose. Have you checked the oil pressure.

I have a df 140 with 1700 hours on it and some times when I start it I get a bit of chain rattle, that tells me that the ratchet has not locked up against the chain guide.

On the tensioner housing where the ratchet leaver is, if you look there is a little tiny spring that keeps the leaver into the teeth as it moves out, I bet it has fallen out that is why it wont lock
and when you rotate the engine backwards and forwards the plunger moves back into the housing.

[RALKITE]

I haven’t changed the chain or tensioner but at last attempt
I noticed a small clearance between tensioner and chain guide. As I loosened nut and bolt heard a click and tensioner had rocked out to next notch. Large amount off slack was gone.
reassembled and started, noise reduction was significant but not totally gone.
about to borrow a oil pressure tester.
also took off gearbox to do water pump and run sans leg no change to noise.

[RALKITE]

Problem solvered. Two issues
first was that after repairing bent valves a piece of valve guide that must have been cracked or fatigued came into combustion chamber and embedded in squish area of head and tapped on piston.
second. The cam chain tensioner mount surface has slight burr that both allowed oil pressure to leak off and linked the tensioner so plunger could lock in a position that would neither push out or return in.
removed both and all is good.