Cam chain tensioner leak

[alfredo]

Oil is leaking slightly from the cam chain tensioner nut. I can't seem to get it tight. I turn and turn and turn and it just seems to never stop. I also think I am messing up the adjustment every time.

How can I get this thing seated and stop it from leaking?

 

[littlebill31]

There is a rubber o-ring that fits in the cap groove. Might need a new one.

 

[alfredo]

There is a rubber o-ring that fits in the cap groove. Might need a new one.

Just checked it. Still looks fresh. The cap is a new one from mikes.

Should it spin forever?

 

[xjwmx]

The exact replacement o-ring size is 1" o.d. 13/16" i.d., available at Do It Best, or probably any other hardware store. I replaced mine, no more leak. Ppl have also ground the nut down to expose more of the old o-ring instead of getting a new one.

 

[xjwmx]

Should it spin forever?

No. It won't tighten is the problem then Doubtful that it's stripped because it's so big. Shaft is spinning with the nut - is the lock nut tightened down? Is something broken inside?

 

[littlebill31]

The big cap nut? no, it should stop. That's what is used as a lock nut on later models. If it keeps spinning, and the tension adjuster rod hasn't broke thru yet, then something is amiss with your rod.

 

[xjwmx]

The big cap nut?...That's what is used as a lock nut on later models.

I think it's the earlier models that don't have a separate lock nut.

 

[littlebill31]

Sorry, I should have been clearer. There is a lock nut in the cap on the late models.

 

[xjwmx]

There is a lock nut in the cap on the late models.

The late models have two nuts. One, a thin one, is the lock nut. It keeps the adjuster from turning once adjusted. The cap nut screws down until it meets that lock nut. Its purpose is mainly sealing. The stock tool kit has a good wrench in it for the lock nut.

 

[littlebill31]

Oh well.

 

[alfredo]

Yeah, mine is just one nut that doesn't have a lock nut. Anyone know what size the lock nut should be? I will go to ACE and hunt it down.

 

[xjwmx]

Same size as the cap nut. Take it to the store and find a bolt that fits the cap and then buy a lock nut that fits the bolt. But it would probably be thicker than ideal. Probably cheap to order the lock nut from a dealer. I'm assuming the early and late adjusters are the same size, only diff is absence of lock nut.

 

[alfredo]

Yeah, it doesn't look or feel stripped in any way. Just keeps spinning and spinning. I guess it would stop eventually if I tried. I think maybe it gets to the wall then starts to thread the rod more and more until it eventually will pop off.

I should have a lock nut right?

 

[xjwmx]

I should have a lock nut right?

Well, it wouldn't hurt. But ppl apparently get by without them. Maybe cleaning and lubing the threads of the adjuster and cap would help. If it tightens and still leaks, the do the o-ring. Since you're going to Ace, do the o-ring anyway and see if it helps.

 

[5twins]

It depends on the year of the adjuster assembly. '78 was one of the few years that didn't use the lock nut, only the cap. The cap acts as the lock nut for your year. Maybe that new cap is not the same as your old one. Maybe it's not threaded as deeply or something. I'd try the old cap to rule it out as the problem.

 

[littlebill31]

I don't have one and it's fine. '76-79 didn't come with them either, according to charts.

 

[xjwmx]

I totally missed that you're trying a new cap. Therein lies the problem...

 

[5twins]

The adjuster assembly changed 5 times during the model run. Yamaha eliminated the lock nut for '76-'79 models (although I have seen '79 Specials w/the lock nut assembly) but then went back to using one in 1980. Apparently, just the cap didn't work as well as they thought it would .....

I never liked the idea of just a cap on my '78. What's to stop the cap from turning the adjustment screw and throwing your setting off as you tighten the cap down? Right - nothing. I swapped the rod, screw, spring, damper washer, and lock nut from a later model into my '78 housing. I'm not sure you can just add a lock nut. The rod is definitely different and the screw may be too.

The o-rings don't last long. They don't protrude much from the cap so there's not much sealing pressure exerted upon them. It doesn't take much time or wear before they start to leak. I replace mine almost every year. That's OK because I bought a bag of 100 from McMaster Carr so I have more than a lifetime supply, lol.

 

[BigBoreSwede]

Hey Alfredo.

After my re-build of the top end I had the same problem as you. Just now, reading this thread I maybe see the answer to my problem

I have a -81 engine but have the "D" model mounted. According to this info I should have a "E" model.

Anyhow, after getting the tensioner flush the cap nut is not deep enough. Now I have 3 copper washers mounted to be able to get it all tight.
Even if it not right the engine runs and sounds good so I guess it works fine

(you can see at the pic there´s a whole bunch of whasers there)


/BigBoreSwede

 

[littlebill31]

I tried to put a nut on mine, but with a '81 you can't use any old nut. It has to have a tapered end. It won't fit in the 6 bolt housing.