Cam chain manual tensioner stuck?

I have an 82 650 Seca with the manual can chain tensioner that I think is stuck. I have had the bike for for about two months and have been concerned about a noise the engine is making. The previous owner told me that all XJ's make the noise but I was not convinced. Today I took the valve cover off to replace the gasket due to a leak. I noticed grooves worn into the top of the cover over the cam chain. I checked the cam chain and there is a lot of slack. I tried the tension adjustment per the Haynes manual, (loosen the lock nut and back out the bolt, retighten the bolt and lock nut.) but there is still a lot of slack in the chain. The chain and sprockets look to be in good shape with no obvious wear. The links have no "slop" link to link and fit the teeth on the sprockets well. The Haynes manual warns about bending the tensioner from over tightening and it was pretty tight when I backed it off.

Can I take the tensioner off with out a major tear down of the engine? Is there more to the tension adjustment process?

 

Yes you can remove the tensioner. Many of these stick and a good cleaning can't hurt. Before re installing it make sure you soak it in oil. Best thing for it.

 

Bought mine with 27,000 miles on it & the cam chain was really noisy. Tried adjusting it with no luck. When I adjusted the valves, chain was loose. Took tensioner off & looked where the lock bolt was hitting the push rod, it was at the end of it's travel. The round rubber bumper on the end of the push rod that presses against the chain guide was deformed also. The tensioner assembly is no longer available, but a new chain is ($50.00). What I did next I consider "hack". I filed the end stop of the push rod about 3 mm (to get more travel), shimmed the tensioner spring with a spacer & put it back together. Adjusted chain as normal, it is tighter. Started it up, it is quieter. Not new-chain-fresh quiet, but better. I plan on replacing the chain, maybe...

 

Sorry to hear your part was made of "unobtainium" Smoker, seems to creep up on us with time. I'm not sure if you could substitute the cusioned plunger off of a 650 into your housing. Just thinking. I have a 650 and a 750 tensioner sitting around and would be willing to mic it out for you to compare. Miss the HWY 49 run from Auburn to Placerville (Hangtown in my world and always will be) in October. Ahhh, the smell of Apple Hill is just wonderful that time of year.

 

Popped the tensioner out today and it was stuck. I had the bolt all the way out when the thing finally let loose and shot the spring and plunger across the garage. Looking at where the bolt marked the plunger, it is about 3/4 extended. The rubber part of the plunger looks to be in good shape. Should I be thinking about a new chain?

 

Why don't you try readjusting the chain tensioner first and see how it works?

 

Yep, listen to Nick! Get a spray can of brake cleaner and clean it out then soak it in oil. I do mean SOAK. Drop or dip the parts in oil before reassembling and installing. If the plunger head is good and it was only 3/4 extended then one or two clicks should tighten that camchain right to where it needs to be.

 

Got everything back together today. The chain tightened right up when I loosened the adjuster bolt. The engine sounds great. Even fixed the valve cover oil leak and checked the valves.

Took her out for a spin and she is running a lot quieter. Now I can hear whats going on around me. Thanks for the info!

 

Hehe.... I like a happy ending

 

To remove the tensioner, do you first have to drain the oil?

Can you remove/install the tensioner without having "things" lined up, or
does it have to be in the C position?

This is for an xj750rl seca 1984.

Thanks for any help on this subject.


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Oil doesn't have to be drained. The tensioner mounts above the sump. You can remove it in any position but it will only tensioned correctly if it is aligned with the C mark.

 

For got to say that the engine is best rotated with a 19mm open end wrench on the flat part of the crankshaft that is visible in the center of the relucter plate which has the T and C marks on it.

 

Thanks for the reply!

I rather not remove any covers that may need gaskets.

Is the C position first cylinder TDC? (If not what is C?)

If so I will just use a long HB pencil down the 1 spark plug
hole, center stand, hand turn back tire, all plugs out....

Anyways, I will remove the tensioner and take a look.

If it is stuck, unsticking it will be great, then just re-install and things
should be OK (In any position?)


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This is what the manual has, but my tensioner looks different.



Mine has a 12mm nut that has fine threads (That will unscrew)

The ones posted seem to have a large allen key type round end nut.

Could mine be manual?

The one in the pic above dosen't have a spring...(manual?)


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The T mark is first cylinder TDC. C is for the camchain tensioner. It is actually a square C. i.e. the side, top & bottom are straight lines. Set the pointer between the top & bottom lines and reinsert the body of the tensioner after first pushing the plunger all the way in. Then after torquing it's bolts to 7.2 ftlbs install the top 12mm hex nut. This is what pushed the plunger in to set the tension. Torque it to 11 ftlbs and you're done. The manual diagram above shows a manual tensioner. The 84 RL Seca has amn automatic one.

 

BTW which manual do you have? Is it the Haynes?