Hi guys. I am working on my son's '95 XJ6. The famous chain rattling has persisted through the years upon start up. I took apart the tensioner to get a grasp of the engineering for it. I bought a used updated tensioner second hand. { used }. Upon installation i dropped it. Putting it back together I noticed that the only difference between the two is the main body which omits the hole for the hex key adjustment. Upon reassembly I noticed that the bushing inside that has all the slots for the hex key adjustment is not only there but impedes the backward movement of the plunger. My question is should I omit this part or is it essential for the proper function of the unit. Also, if the only difference is the main body then how is the revised unit better. Thanks for your thoughts.

 

My memory is slower than I like these days.

BUT

The updated unit with the Arrow on the end of the casting, has a different spring rating. Meant to "push" the chain stronger on start up until the 80PSI oil pressure arrives and takes over.

Does not always work as planned.

I had these units in and out of both my 300's in utter frustration, and eventually just went with "common sense" and fixed them both.

The attached PDF is what I ended with, and they are still silent today. Not in my fleet, but the caretakers complain not of chain rattle.

HINT, I speak Aussie, and a tad off centre at times. Good luck.

 

Thanks for the quick response. Your pictures are quite helpful. Do you think the small tube with all the notches in it is necessary or does it need to be there? It seems to get caught up in the small guide in the main body. Useful when you could access it with the hex key, but now just a pain in the butt.

 

YES.

That arrangements is compressed by you prior to installation, and fiddle as they come to get it compressed.

When installed, and IF the cam cover is off (recommended, but not mandatory) use a flat blade to work the tensioner from the backside of the blade, thus :"firing" that cylinder and pre tensioning the chain.

OR

Start the engine, and the whipping of the chain wll also "fire" it, BUT the 2 seconds rattle will wake the dead, and scare last nights meal out of you.
I go the long way mostly, as 1 of the many times I had that thing part out failed to "fire" with the start up.

 

Having been down this rabbit hole more than once, a couple of thoughts to add to Grant’s excellent piece.
The current state of play with my car is that having replaced chains and tensioners some time ago, I have a light rattle on the first start of the day , say 7 times out of 10, but none thereafter during whatever use the car is put to during the remainder of the day. Ambient temperature seems to make no difference, and the rattle disappears after a couple of seconds. Notably, no rattle at the 1500rpm zone.
Over the years, I have read several posts from members who swear by 20/50W oil as a solution to the problem. The success of this as a solution would suggest that oil pressure leaking away from the upper tensioner is the underlying issue, with the thicker oil being much more difficult to leak away. I have resisted going down this path as I am convinced these engines do need the much thinner oils specified, and I don’t want to solve the timing chain rattle at the cost of inducing some more expensive rattles!
However, logic would suggest that we should focus on the spring, whose only role seems to be applying the initial tension to the chain pending the arrival of oil pressure. If the spring were applying more pressure, I feel sure the problem would go away. I am currently pondering removing it and attempting to stretch it to give more pressure. I have thought about fitting a shim to achieve the same result, but am nervous about introducing small metal parts where they were not originally intended.
In truth, not on my high priority list, as it a very easy issue to live with and doesn’t seem to be doing any harm, but the quest for perfection will inevitably lead me there!

 

Great! thanks for the response gents. Removing the valve cover is something I need to do anyway. I removed the cam sensor without setting TDC. So I will rotate the engine until the marks on the camshaft line up. Tensioner goes in first of course. So, helping the tensioner from under the cam cover makes perfect sense.