Replacing the upper timing chain tensioner on a granddaughter's 1996 XJ6 to (hopefully) cure the momentary startup grind/rattle. The one in place is the original style with the external cover to allow you to "wind in" the spring. I've removed the valve cover and spark plugs just to see what's going on there, & make engine rotation easier. Just got my 1-5/16" socket from Amazon (of course, largest I had was 1-1/4"). Have read through various posts, on the issue, but have a few questions.

1) Why does the new tensioner need the piston spring wound back? Couldn't the new assembly just be inserted, and let it be compressed as the bolts are tightened? Does winding it back help ensure that the piston doesn't fall out while unit is being inserted?

2) Should I somehow put pressure on the chain inside the timing cover on removal and insertion of the tensioner to minimize the risk of the old or new piston coming out?

3) Would a small dab of thicker grease on the piston keep it from initially wanting to slide loose (the rest of it oiled)? (As you might can see, I really don't want to potentially have to get into removing the timing cover).

4) The fuse chart says the fuel pump fuse is a 30A at #7 in the boot fuse location. There is a green 30A there (the only 30 A in group), so I assume that's it. If I remove that, considering I have the coil packs off and plugs out, is there any real need to hunt down the fuel pump relay(s) before "bumping" the engine to set the new tensioner piston (with valve cover back on, of course)?

5) Is there any real need to replace the longer bolt from the original tensioner (the side that holds the little cover flap)? It can't possibly interfere with anything inside the timing cover can it? I could space it back with a couple of washers if it's rally an issue.

Thanks in advance for any answers or suggestions!

C

 

Welcome to the forum cathammer,

Your post was automatically locked for moderation which is why it hasn't had any replies. I can't see any problem with the content and have therefore unlocked it.

Graham

 

I will answer what i have done many times, in the order you have asked them:

1) It needs to be wound in, and when you have done a dozen or so, the workings are obvious. It WILL NOT wind up with the bolt up method, that will simply crack the ears, or deform the piston assembly,
2) Since you have the cam cover of, I suggest using a large blade screwdriver to lever the OLD unit out, as that is the one that can drop its piston. Working that same method with the new installed, MAY fire it off, but I have had little success with that method on the top unit, about 85% maybe, the rest is fired when the beast starts up, and revs past 1500rpm.
3) Doubt it. The new unit, with the assembly wound in, is quite stable, and since the angle is basically "tail down", the risk is zero in my opinion. I am ASSUMING, the cam angle sensor is removed?.
4) Never pulled it, dunno.
5) Dont remember, I always find a shorter bolt is my bolt bucket, and simply install that. Washer packers is just NOT Jaguar, really.

This attachment is what I have done many times, and not dropped a piston ever. Clearly, ignore the bits that dont concern what you are doing now.

The initial start after installation can be scary, but you get used to it. Its just that initial "firing" of that wound back assembly, BUT, if you have "pre-fired" it somewhat, that rattle will be less.

Have fun.

 

Never drop a revised tensioner down through the right side of the engine

The spiraling dogtooth ring can crack on it's way down and never see the crack on retrieval

Ask me how I know

On mine I still have the original installed and have another revised in hand

 

Thanks. Please forgive my ignorance, but I'm not quite following what you're saying here. Are you talking about dropping the tensioner's piston into the timing chain cover during removal?

 

It was the donor car as I dropped it past the cam position sensor through to the ground

 

Thanks for the info and attachment.

Since my inquiry was delayed in moderation, I went ahead and removed the old tensioner and installed the new one (with the spring wound down in the piston). No problems...the old one came out in one piece. I loosened the bolts a bit & tapped a piece of wood against the assembly's exterior casing "ears" to sort of break it loose from the engine block, then lightly did the same against the chain opposite its location to get it started moving out. Removed the bolts and gently twisted the assembly side-to-side as I extracted it.

Before inserting the new one, I poured a bit of oil into the casing, and ran some lines of assembly lube up & down the piston before replacing it in the casing. This seemed to provide enough surface tension to allay my fears that it could easily slip out, and as you said, it was essentially "tail down", anyway (besides also moving in a direction where nothing could snag it and pull it out).

I had to wriggle it a bit when it met some resistance going in, until I suddenly felt a slight "pop" and it slid in further until there was just a little space to be tightened up with the bolts (used the washers, sorry). I assume the piston's "ears" weren't quite athwart their perch on the back of the chain guide at first. Wish I could see down in there better to be sure.

Left it there for the night, as I was tired, and that's when you started making stupid mistakes. Will try to finish up today, if family activities allow.

May try bopping the chain with the mallet and wooden stick a few times to see if I can get any "pre-release" on the spring before turning over the engine.
As to that procedure...Any suggestions on low long or often I should "bump" the engine over before hooking things back up to let it run?

Thanks again,
C

.

 

Ahhh, OK. I had my own moment of dread when I was reinstalling the cam sensor. I had put its adjustment lockdown bolt lightly back into place when I removed it, just to identify where it went in reassembly. When I came to that point, I stupidly removed the rag I had stuffed in the sensor's hole before I took the bolt back out, and almost fumbled the bolt as I removed it. Dropping it down the hole would not have made my day.

Cheers,
C

 

The timing chain seemed pretty tight after whacking a dowel against it a couple of times (may have gotten a bit of spring release), so I buttoned the valve cover back up, removed the fuel pump fuse & turned the engine over a few times...No sounds of teeth breaking off of anything.

Put coil packs back on (need to order new gaskets...used an O-ring in place of one & that seems to work OK), & reinstalled fuel pump fuse. Held my breath and cranked it...
Started right up and sounds much quieter, even revving it. No road test yet, family stuff now, but maybe everything has worked out . Thanks to those with helpful info, including that on existing threads!

Now if I can see to the AC situation....

Cheers,
C

 

Well done.

The "firing" of that thing is a tad iffy, and the screwdriver on the backside of teh chain, and work away as a lever "sometimes" gives some relaes.

I simply button the thing up, and start it, and rev to 1500ish, and thats it. That Unholy rattle is what scares the hell out anyone not familiar with them.

You have done well, have a beer on us.