Hi y’all. New guy, first post – if it’s too wordy, please tell me. Black ’04 XK8, 80 kmiles, had it a month and a half or so. I heard the “transmission chirp” occasionally (more of a honk, like a goose, or maybe a bark), mostly during kick-down shifts, sometimes during upshifts at moderate throttle. Short duration, nothing particularly worrisome. But then a couple of times after kick-down and running hard up 90 mph or so then letting off, a loud, pronounced hooonnnk noise for about a second followed by a very hard shift into the next gear (4th, I think). Changed the trans pan and fluid, filled per the procedure and it acted fine for a couple of weeks, no noise, no slam shifts, good behavior even after kick-downs and hard acceleration. But now this week two or three more episodes of noise and/or very hard shift after kick-down. I’m not good at sifting through forums so forgive me if I’ve missed something obvious, but I haven’t seen any explanation of what actually causes the noise (I feel sure my “honk” noise is just an extension/exaggeration of the “chirp”). I’m pretty much convinced that it’s slipping clutches, and I can see how refreshing the fluid/putting in an additive could help in the case of a “chirp”. But I’m becoming very suspicious that the prolonged honk followed by a slam shift is caused by a clutch or brake hanging (the operational description describes three clutches and two brakes that are sequenced by the solenoids and valves). Adding to the suspicion is that “overlapping shifts” are part of normal operation: “Overlapping shifts can be described as one of the clutches continuing to transmit drive at a lower main pressure until the next required clutch is able to accept the input torque”. The symptoms imply to me that pressures sometimes aren’t correct and that clutches/brakes are fighting each other. That’s what it feels like too, and it’s not a good feeling – the clutch wear in these events must be horrendous. Since it’s usually fine but occasionally not, I can’t see how simple re-programming would correct it – am I missing something? I’m inclined to replace the Mechatronic control unit, probably both the valve body and the ECM. I would certainly be interested in others’ opinions and experiences - any and all input appreciated.

 

Volbrewer, This reminds me of a TSB I've seen. The TSB discusses noises like yours from the Tranny and as I recall recommends an additive to relieve it. I'm sure smarter folks will correct me if I'm heading down the wrong path here, but give it a look, it may help.

John

 

Thanks Johnken. My understanding is that the additive is no longer available. The current practice seems to be to change the fluid/pan/filter, which I've done. I kind of think this issue goes beyond additives and fluid changes, but not certain about that. What's odd is that as long as I drive it "normally" it behaves perfectly.

 

Someone will chime in I hope, this is beyond my expertise now mate. John

 

I had this and to fix it had to change the transmission fluid and filter. No issue anymore. It's not a cheap date though.

 

We did have the Transmissionsquawk issue with our 2005 XK8, and by adding the Transmission fluid additive Part No. C2C 37157 did correct the issue,
But as BMW also had the same issue and this was a ZF supplied fluid, there was no Jaguar branding on the bottle only on the brown box with the Jaguar partNumber & logo on it. So perhaps the other car manufactures which used thesame transmissions and had the same issuer may still have stock or still sell this?

Redpoptop

 

Volbrewer,

What ATF did you choose? Whatever it was must meet the Shell M1375.4 specs....

Before tearing into your ZF I would have a trusted dealership perform the ZF Adaptations Drive Cycle reprogramming. That essentially clears and resets your transmission parameters and you start from scratch with the ZF learning your driving habits and adjusting accordingly. After we did an ATF/pan/sleeve change, the reprogramming (done in late July 2013) finally cured my wife's 2006 XK8's flaky transmission behavior that she had been complaining about for months. I found the price to be negotiable among the two dealerships I obtained quotes from and eventually wound up paying about $150 for it. I also checked with a couple of local indie shops who said they could do it, but one admitted to never having done it before. I decided to go with a dealership that routinely does it five or six times per month. As I said, it flat-out fixed the issue and my wife has never complained about it since....

The procedure is documented in TSB JTB00145. Do some research and determine if this might be your next step....

 

I used genuine ZF Lifeguard Fluid 6, in spite of assurances from various sources that some much cheaper fluids would work - best to know that you did your best. Headed out on a jaunt with a friend to see if we can duplicate the issue. If so, I'll let the Jag boys have a go at the reprogramming thing. Thanks all.

 

This is the first time I've heard of the updated and correct fluid not correcting the 'honk'.

How strange.

 

I just had a very low mileage 2006 in my shop with the same issue. Kind of a honk or sqawk into 3rd. As stated, there is a bulletin regarding additive, etc. No longer supplied. I simply changed the fluid using Lifeguard 6, and the honk issue was resolved.

 

I should have been more clear. First fluid change didn't do it, it took 2 (my guess is that the torque converter retained too much of the old oil the first time) but it's been chirp free over since.

 

The actual chirp thing went away on mine, but it took a good two weeks after the fluid change. Just got back from the hundred mile jaunt - I did several kick-downs and run-ups to 75 - 90 mph and it never misbehaved at all. Situation resolved itself? Maybe; we'll see ...

 

congrats, supposedly the noise doesn't hurt anything but it was sure annoying.