Tope End Rattle

I NEED help.
81 XJ 550, starts fine, runs fine ....everything fine ... except when under load there is this load rattle that makes me think that the cams are ripping through the cover any minute.
Before I capitulate i would like to ask for advice, insights, etc.

I have, according to bigfitz instructions, loosened and retightened the automatic cam chain tensioner.

I have 18900 miles on it .. when it idles, no problem, just under load ...drives me nuts, accelerates fine and everything ... it sounds like its coming from the left side more than the right ....

Thanks guys

 

-Exhaust leak at a head/pipe junction.

-Cam chain didn't adjust; you might need to pull the adjuster apart and smooth off any "divots" in the outer plunger. Somebody may have cranked the locking bolt so tight it put enough of a divot in the plunger that it doesn't slide freely when "unlocked." It's very common.

-Be sure the safety relay hasn't broken loose and started rattling against the cam cover.

-Exhaust pipe(s) loose at collector junction.

 

Thank you bigfitz!! ... I will go through the checklist; last time I did the cam chain adjuster, I didn't pull the plugs and the 2 slow rotations clockwise, smooth stop at 'C' and then the quick counterclockwise turn

 

That's good, because all that turning and backing up is the way to "trick" the automatic style tensioner. Yours is manual.

No "quick counterclockwise turn" required for the manual one; roll it over slowly and align the "C" mark then loosen the nut, then the bolt, tap on tensioner; re-torque bolt to spec, tighten locknut.

Often less than gentle owners OVERTIGHTEN the locking screw and the resultant "mushroomed" dimple in the main plunger is enough to keep it from moving as it should when you loosen the locking bolt.

This is easily remedied by disassembling the tensioner and cleaning the plunger up with a small, sharp file.

In this exploded view of a used tensioner, you can see the screw dimples in the large plunger. If those are extreme enough, the plunger won't move freely when the adjusting bolt is loosened. (The item indicated by the arrow is a rubber/metal composite "damper" and not germain to this discussion.)