Will somebody offer an explanation to my start-up noise?
 

Without actually hearing the grinding noise, two immediate thoughts come to mind:

1. loose Starter Motor securing bolts (lower one arrowed in blue)
2. worn Bendix (arrowed in red) and or damaged starter ring on the flywheel

Attachment 119718

When the ignition key is turned, the starter motor rotates and the Bendix which is engaged with a toothed ring on the flywheel rotates the engine (apologies if that explanation is unnecessarily basic for you!).

Graham

I agree with Graham, and add the following:

The top timing chain tensioner gives an unholy rattle/gind/clatter when it has its moments. It is a very common failure item. It will NOT destroy the engine, it just is a "Non-Jaguar" sound that scares the hell out of the unaware onwer.

There are heaps of write ups on this in this section.

Maybe even a "stickie" at the top?.

I wondered about the timing chain tensioner too, but from the description that it didn't make a noise on start up from cold, discarded that idea. I have the timing chain start up issue, but it only does it on the first start of the day from cold. All starts thereafter are fine until it is left for several hours and gets fully cold again.
Does the grinding noise last for long, or is it just a few seconds?

I appreciate everyone's input. countyjag, the grinding noise that I mention only happens for a second. on start-up the engine will roar to life as usual and the grinding noise follows almost simultaneously. I should really record the sound. it sounds as if I'm trying to start an engine that's already running

I can envision the sound perfectly. Next time you run into the store, try leaving the car in the "on" position for 4 or so seconds before cranking, and see if that helps.

Agreed.

Then remember that Jags are female, nuff said.

My 3.2 did the exact same, and the noise was not there at cold very often, but that hot restart after a few minutes, sometimes seconds, gave that horror.

I finally deducted that it really depended where the engine stopped in its 360deg rotation, and the "backload" of the cam lobes on the chain, that was the real cause of the tensioner and blade rattle.

Mine had the uograde unit, but a new one shut it up 100%, BUT, 140000kms later I hear it again, oops.

my 97 XJ6L has done the same thing for over 4 years. I changed the upper tensioner with no results. My friend ( who is a factory trained Jaguar mech swears it's the starter running on) If I get in and turn the key to "run" for about ten seconds and then start it, it won't do it, leading me to believe he's right. Either way mine does exactly as yours and so far it's no worse for wear.

Bingo, spot on. Glad I'm not the only one! Misery loves company!😄

Haha!
It's pretty rare that I get the noise, happens maybe a few times a month. I do this every time I start the car now, just for good measure. A few times it almost sounded like the engine was about to flood, though, definitely scared me--happened in the same scenarios, car was off for about 30 minutes. Guess it's pick your poison. Maybe my injectors could use cleaning at almost 260,000 km...

Is the noise related to the starter motor or the engine? If the starter bearing goes dry it will make a noise after the engine fires while the starter slows to a stop. Lube the starter motor bearing at the bellhousing end.

I truly appreciate everybody's input. I've had a hunch it could be the starter running on as JTsmks said. I should also mention that a much quieter but still audible grinding can be heard when I'm accelerating from zero to about 30mph, after that it's gone. it sounds like it could be associated with the grind I hear on start up.
I asked a mechanic about this but he said if it were the starter than it would be constantly grinding, not stop at certain speeds

that sound you hear while driving is the timing chain/guide/gear train. Mine does it too. Again changing the upper tensioner did little to quiet it. I just live with it. It's noticeably less with an oil change and noticeably more when I'm coming up on oil change time. Dropping in a can of STP seems to keep it in check between changes.

I've decided that some on start is timing with the starter adding to it. The driving from zero to about 1800 RPM is timing. Mine was doing it at 30k so my thought is I go through all the trouble of changing everything for it to just do it again. Mine has 92k on it now and has always done it since I got it at 30k, like I said, no worse for wear. I just live with it, use quality oil at regular intervals and throw in a can of STP between changes. To lessen it at start leaving the key on for 5 to 10 seconds before start seems to help.

Here is the TSB issued 20 years ago.

bob gauff

if your referring to the upper chain TSB, been there done that, had the new and went with a newer new, no difference.

My noise was the fact that my oil was too thin and when I switched to 20W50 Amsoil it went away. My timing tensioner dealies were groaning.

Same, switched to 20W50, the tensioner (new model) noise stopped.

I had that grinding noise at start, would last one second or so, and then it would work perfectly. Problem was solved with a new starter.

Used ones can be bought at reasonable price and replacement is straightforward.