I've been trawling the X300 "noise" threads and can't find anything that resembles my latest one. In the last couple of weeks my 3.2 has developed a very intermittent and very brief, what I can only describe as a light "scratching" sound, sometimes it appears either on a light increase in acceleration, or gear up-shift but doesn't do it all the time, appears randomly for a split second. It sounds like very quickly scratching a finger nail over a hard surface / blackboard - for no more than a fraction of a second. I keep thinking, dry throttle linkage? loosening drive belt? ???? Trans? The trans performs fine, fluid level is fine. It sounds like it's fairly close to the fire wall, but is so quick and irregular that its hard to be sure. The only consistency I can detect is that it seems to pop up when under some sort of load, but not heavy load, and it will appear 1,2,3 times on most trips of around 20km or so.

It isn't so annoying I can't live with it, but I'm concerned in case it's the tip of an iceberg! Any ideas anyone?

Cheers,
Tony.

 

Tony,

A few things come to mind.

First is the infamous top timing chain tensioner is failing again, they do that. The modified units do have a life span, and that would depend on the oil servicing periods, grade of oil, mineral or synthetic. etc.

Sometimes the torque convertor can "ching" erratically on the HP22 trans we have in the 3.2 cars. I had a sort of similar noise in mine when I got it 3 years ago, along with the chains etc, and I dropped the "good looking" fluid and refilled with Synthetic, and did it again a month later, and once I had done 6 of those, the trans was soooo sweet it kinda scared me a tad.

Thirdly is the cat convertor/s may be starting to crack up and rattle erratically, not common, but it does happen.

 

Thanks for the hints Grant, very helpful. Having had the chain tensioner done only about 2,000k's ago (and hoping for a bit more life out of it), and given the rarity of the cat con's playing up, I'm inclined to try the trans fluid change first up. Mine does look good, but it hasn't been changed since I've had the car. I'm curious as to why it would take 6 fluid changes to make the difference though. Why do you think that was? Also, would you mind telling me what brand / spec synthetic fluid you are using?

Cheers,
Tony.

 

Tony,

Simple maths.

The trans is about 15ltrs dry (that means REALLY drained as when rebuilding it), and also includes about 9ltrs in the convertor, (which you cannot drain).

So when 4?ltrs is added at service drain and fill, it gets diluted quite quickly, so do it again, and the dilution is less (obviously), and so on.

I had a chart here somewhere from ZF that gave the specs for doing the slow purge (as I call it), and a 15ltr "dry" is about 6 - 8 drain and refills, at 4ltrs per drain and fill.

I use Penrite "Multi vehicle full synthetic" trans fluid.

Nulon makes one also.

The same fluid is ALL my Jags, and that includes TH400, BW8, BW/DG, BW65, and NO issues at all.

At the risk of being annoying, the top chain tensioner did little to shut mine up, much better, yes, but still not as I would expect. I removed the timing cover and replaced all the blades, dampers, etc, very sad little items, and that made it SILENT, as it still is at 40000kms later.

Another thing to look at is the idler pulley on the a/c belt. The original is plastic hahaha, and the bearing is encapsulated in that plastic, good idea NOT. I replaced mine with a steel one (same as Falcon/Commodore, and EP002 is the part number I think??) and $15, and the bearing is a simple 6203 2RS and about $3 anywhere.

 

Thanks again Grant, more good info. I'll start working through some of those things. Funny, I've sometimes thought it would have been simpler to keep the Falcon I had before the Jag (don't panic, just kidding, wash my mouth out!!)

 

WASH YOUR MOUTH OUT INDEED.

A swill of Fosters, followed by a double JacK Daniels, and then another JD, should sort that little stumble of thoughts.

Of course if was a XY GTHO then maybe you did do wrong, mmmmm.