I have no idea how much airflow difference the duct really makes. But I do know that spending $40 to bolt one onto the car again will cost far less than having to replace a toasted alternator. So I regard the duct primarily as another measure of preventive maintenance insurance....

Great. Now I gotta crawl under my car and see if I have one, since I can't remember from the last time I changed oil.

+1

The cooling duct is in two parts (see my attachment from Post 16):

Jaguar XK8 4.2 - Alternator Cooling Duct.pdf

We were/are all missing the lower section. Without this it looks as if hot air from the engine and brakes is more likely to be directed through the remaining section onto the alternator.

Graham

I found mine in the trunk. Seems like PO didn't bother to put it on last time the oil was changed.

That was a stroke of luck. I'll need to look too, maybe we can set a Guinness record for the number of XK owners peering under their car at one time.

Sigh. Count me in.

I gotta laugh--I wonder how many Jiffy Lube locations have these funny looking plastic scoops hanging in a tool box. Gee, I wonder where this came from???? This is probably the number one reason I do my own maint.

hmmm, I have mine but it appears that the previous owner installed it upside down and that is how I put it back on when i changed the oil. Unless I am looking at the drawing wrong or things are oriented differently on the 06?

The duct fits the same way on the 4.2 as it did on the earlier 4.0. Attached pic is my 4.2.

Getting the 2 raised 'hooks' on the front of the duct properly engaged is awkward. This could be why so many go missing......?

Graham

This thread might be a good place for a friendly reminder.

Never Never NEVER crawl under a car that is supported by only a jack!

Please use quality jack stands or some other approved method.

I will give you the method I have been using for years on many cars.

1. Jack car up using hydraulic jack at approved lifting point. Make sure the ground you are working on is strong and stable, like a concrete floor. Black top (asphalt) in the heat will become soft
2. Place jack stands under a point you are 100% sure is strong enough to support the car. Make sure jack stands are level and have 100% contact with the ground.
3. Slowly lower the car on to Jack stands
4. Snug hydraulic jack back up to lifting point but do not lift off of stands
5. Before going under the car give it a good shake to make sure all is stable.

No repair no matter how simple or quick is worth risking your safety for.

Have fun!

Yep, that's good common sense that we all need to pay attention to....

In my younger days I would crawl underneath a car supported solely by its jack in a heartbeat. I thought I was quick enough to scramble out of the way if I heard any creaking or groaning from the jack. I was fortunate, but I was also foolish. These days, it's either multiple jack stands or a good set of ramps before I will even think about crawling underneath....

Thanks so much for that picture, just double checked and it was indeed installed upside down, which was probably causing it to pull hot air from the engine compartment. Very glad i stumbled onto this thread, everyone should double check how there's is installed since it seems to fit fine upside down and the lube shops seem to be unfamiliar with these things.

My wife was in the dealership's neighborhood yesterday afternoon so she stopped in to pick up the alternator air duct that I ordered from them last week. What a flimsy, overpriced plastic part, and much smaller than I had envisioned. Now that I can hold one in my hand, I doubt very seriously if this glorified milk carton flap makes much of a difference as far as significantly increasing the airflow to the alternator is concerned. While the dealership did grant me their $35 "preferred customer" discounted price, this duct should not cost more than $5....

I'll install it this weekend simply because I ordered it and I now have it. But I would guess that it will not lower our alternator's operating temperature by more than one degree at highway speeds....

that seals it, i'm not ordering one for mine. thx jon!

I put the car up on my ramps this morning and installed the duct in less than one minute. A glance at Graham's photo of his duct gives you the orientation, so you don't wind up trying to put it in upside-down....

One recommendation - use a 1-inch diameter washer on the single attachment bolt to spread the load once you crank it down. As I previously mentioned, that plastic is not much better quality than a milk jug....

While I was underneath the car, I took a close look at the ZF electrical connector sleeve to check for any fluid leaks. It remains bone-dry, and I do not see any evidence whatsoever of dripping or blowing fluid anywhere on the ZF pan or behind it. So the mystery remains as to what the dime-sized clear liquid drip spots on the driveway underneath the car about ten days ago actually were. I hope it was simply due to light rainfall run-off. You can bet that I'll keep watching in the weeks ahead. But I hope I lucked out and do not have to drop the ZF pan and change the sleeve with only 43,000 miles on the car....

It's worth considering that many cars have the alternator mounted up top without any special air ducting and run fine for many years.

What is really unfortunate about the location of the alternator is that the bottom mount exposes the alternator to a lot of grit. On other cars that have the same mounting the result has been early failure of alternator bearings and brushes.

Oh, make sure you drain the engine oil and not the transmission oil.

Sounds like a dumb thing to say but I read another thread about this.

Jon, glad to hear that the electric sleeve is not leaking. Bummer though in another way.

Rick, I hear you loud and clear my friend. But if either of our ZF sleeves begin to leak, I'll be there at your first convenience....

The XK8's ZF unit will be tougher to work on than our S-Types', though. It has much more metal shielding around it due to the layout of the exhaust system right next to it on both sides. Good for heat protection, but it really cuts down on the tools-and-hands room....

Well I did my first one today less than 4000 since the last one but about 18 months.

I did have the alternator duct, so I guess that says something for the previous servicing standard.

I put a Jag filter on C2C41611 mainly because I was at the dealer for something else the one that came off was a Fram PH5618.

Oil type and grade is secret!!