Hi everyone, I recently acquired a 2000 Jag XK8 convertible. It's done 103k miles

I'm in love with the car but have a couple of issues. Mostly worryingly, I have had an issue when pulling away at traffic lights on a few occasions.

The car makes a sharp screeching noise (like screeching tyres when pulling off) and then goes into a high gear so I can't accelerate quickly

The message GEARBOX FAULT comes up on the dash.

After driving off for more than abut 30s the gears operate as normal.

And if I stop and turn the engine off, the warning message goes away too.

However this has happened 3 times in a week now and I know I need to address the issue

Also, the car does take 5-6 seconds to start first thing in the morning. It takes longer if the fuel is low

For the rest of the day it starts straight away though.

Any ideas? Thank you in advance if you're able to help!

 

I'm assuming that the noise comes from the transmission. in which case, stop driving it until you get to the bottom of this.

It may just be low on transmission fluid, but it may also be something deeper. Others more sage will chime in here.

Ideally, drain the fluid and remove the transmission pan. Check the condition of the fluid for particles/metal shavings in the bottom of the pan. It will certainly do no harm, and at that mileage the old fluid needs to be replaced unless it's been changed relatively recently (fairly unlikely, unless you have any history?) together with a new filter.

For the slow start, you could try turning the ignition on for a couple of seconds then off, and repeat a couple of times before proceeding to crank. I'd suggest opening a separate thread.

 

Others more sage than michaelh? motorcarman, but unlikely any others.

 

Re the slow start issue - sounds like you're losing fuel pressure overnight. May be a leak but I think you'd smell/spot that but may be leaking injectors. There is a schrader valve on the fuel rail in the engine bay where you can check pressure in the fuel system. Other thoughts: lazy fuel pump or blocked fuel filter.

 

Hi James,

You've received great advice already from some of our top experts.

One thing to be aware of is that Jaguars need strong, healthy batteries. If the voltage sags much below 11 volts while cranking, the Engine Control Module may not trigger the ignition to fire. When starting, the voltage sags immediately as the starter draws maximum current, then the voltage will rise a bit as the inertia in the motor is overcome. I have resolved extended cranking issues on a number of Jags by installing the best quality battery I could source at the time (AGM in cars that are not driven frequently). Many auto parts stores can test your battery, starter and alternator for free, but the best time to test it is when it is cold and has been sitting awhile so you can see the worst-case conditions.

It would also be worth having the car scanned at a shop with the ability to read all of the diagnostic trouble codes that may be stored in your car, including not only the Powertrain codes (P- prefix), but also the Body (B-), Chassis (C-) and Network (U-) codes. It is quite likely that your transmission control module (the Mechatronic, inside the transmission) has triggered at least one fault code that will be helpful in diagnosing the issue.

When the GEARBOX FAULT lamp illuminates and the car goes into high gear (probably 3rd gear), that is called Limp Mode or Limp Home Mode. The ECM and Mechatronic are reacting to a fault and locking the transmission into 3rd so you can drive the vehicle home or to a repair facility, but shifting is prohibited to help protect the gearbox from further damage. Michael's warning to stop driving the car until this is resolved must be taken seriously!

There are a few known issues with the ZF 5HP24 transmission, including pressure control valve problems and cracked A-drums. Follow Michael's advice about draining and inspecting the fluid, but do your research first. It is critical that you loosen the fill plug before draining the fluid. If you discover that you can't open the fill plug after you've already drained the fluid, you're in trouble. Also, study how to set the proper fluid level once you put it back together. It must be done at a specific temperature or the fluid level will be incorrect. And do not use any fluid other than one of the following:

ZF Lifeguard 5
Pentosin ATF 1
Febi Automatikgetriebeöl (ATF) Nr. 29738
VW/Audi G 052 162 A2
ESSO LT 71141
Ravenol ATF 4/5 HP

Valvoline and other companies make fluids they claim are suitable for use in your transmission. Do not believe them! In the U.S., I find the Pentosin and Febi fluids to be the easiest to find, and sometimes the Ravenol (FCP Euro and the eBay seller partscontainer are good sources). ZF Lifeguard 5 is often available from The California Transmission Supply Company (thectsc.com), but it is very expensive. The other fluids are also approved by ZF and are usually available at lower prices.

Cheers,

Don

 

Hi Don,
Thank you for translating my brain ramblings into a coherent English set of instructions and explanations.

It's much easier to read than something that looks like an excerpt from a dictionary. I never did get the hang of it, sadly.

Best wishes,
Mike

 

Mike,

I would never deign to try to translate your posts - they are always perfectly cogent. Please forgive me if it appeared I was doing so.

My objective was to reemphasize your very important warning to James in case he were to think to himself, "That's just one guy saying I should stop driving the car; maybe he's just overly cautious." We've had too many new members ignore the advice of our veteran experts with predictable results.

I greatly admire your expertise and always appreciate your generosity in sharing it!

Cheers,

Don

 

Noooo! Not at all! That's not what I meant. I read your post and thought "I should really have posted a response like that"

 

When I walked up to a car that had had water sitting in the transmission (completely full) I was VERY careful about spending buku money on transmission fluid I KNEW I wasn't going to keep and would be flushed out again. I was HAPPY to find Valvoline All Vehicle type fluid for 17 - 18$ a gallon for the testing. And, as it was a ZF (6hp26), later I was happy to find some Mercon XP as a solution to hyper expensive trans fluids. Super happy...

But, what Michael said. I wouldn't drive the car anymore, at all, until you figure out what's going on. Get under there and drain out the fluid, then drop the pan (careful careful careful with the pan bolts), check the magnets in the pan, and if everything seems ok (no chunks and an acceptable amount of metal dust/mush on the magnets) refill and SUPER gingerly do a few short super slow low load test drives... And this is just me,,, I would be very happy to use Valvoline Multi Vehicle trans fluid until you are sure you have the long term fluid you are going to be keeping. If not, it could literally be hundreds down the drain.

The 5hp has a known problem in it's lower gear A clutch drum and it's seal at the drum. If you (or the PO) haven't driven it til the A drum exploded (if this is the issue) there's a very good chance things are very save-able.

The slow start, if the car sat a while I would change the fuel filter and hope that is just a bunch of gas that turned to sluggy varnish in there in it's long sit up. Or, some gunky injectors or something.

Main thing is the trans right now, I think.

 

Hi Jay,

Under the circumstances, you probably did well to use Valvoline for testing. But to be clear, the problem with James' transmission is probably not water ingress, so there is no reason I can think of to put Valvoline or any other incorrect fluid in it.

And for future readers of this thread, the correct alternate fluid for the 6-speed ZF 6HP26 is Mercon SP.

Cheers,

Don

 

Right O!

 

Hi Don. So, definitely stay away from the Valvoline. I've used it with great success in my other European cars. I will defer to your advise on it even though the specs seem to match the ZF requirements. Have you had any negative personal experience using this atf in a Jag? Thank for your advise - really helps us newbies 😊

 

Hi Mike!

Regarding Valvoline MaxLife ATF, I and other members have researched it extensively, and here is one example of what I've written (copied from one of dozens of other threads on this topic):

Many knowledgeable and respected members of these forums have spent countless hours researching correct fluids for Jaguar transmissions, and one thing we've learned is that Valvoline cannot be trusted regarding the specifications its Multi-Vehicle fluids are claimed to meet. Apparently, they are able to offer fluids at lower prices by compromizing the formulations to make them "suitable" or "just good enough" for use in a wide variety of vehicles. But a fluid "good enough" for use in so many gearboxes can't possibly be optimal for use in any of them.

For example, Valvoline claims its MaxLife Import Multi-Vehicle Transmission Fluid is suitable for use in ZF 3-speed, 4-speed, 5-speed, 6-speed, 8-speed and 9-speed transmissions. Yet ZF insists that the 3-/4-, 5-, 6-, and 8-/9-speed boxes require four different fluids that are not interchangeable or backward-compatible, and if you check the Material Data Safety Sheets for those fluids, you'll find that their chemical properties are quite different from one another.

As another example, Valvoline claims that this same fluid is suitable for use in Ford vehicles that require Mercon SP, Mercon V, Mercon LV and more recently, Mercon C (for CVTs!). Yet Ford insists that these fluids are not interchangeable and, for example, Mercon LV must never be used in a transmission that requires Mercon V, and vice-versa. And Ford states that Mercon C must never be used in a conventional, non-CVT unit! By the way, Mercon SP is chemically identical to ZF Lifeguard 6, which is VERY differrent from Lifeguard 5, yet Valvoline claims their fluid is a suitable replacement for both!

Here's a link to the product info sheet in which Valvoline makes its implausible claims:

Valvoline MaxLife Import Multi-Vehicle Transmission Fluid Product Sheet

Since fluid-related transmission failures may occur over tens of thousands of miles, it may be impossible to realize a fluid is causing your transmission to have incorrect internal pressures, temperatures, torque converter power transfer, slippage, anti-corrosion and anti-foaming properties, seal incompatibility, etc.

The transmission is the second-most expensive component in your vehicles. Is it really worth using a fluid that has been designed to be just "good enough" to work in dozens of dissimilar transmissions for which the manufacturers specify very different fluids? Since transmission fluid needs to be changed so infrequently, why not spend a little more and use a fluid the transmission engineers tested and approved?

For the ZF 5HP24, see the fluids listed in Post #5 of this thread.

Cheers,

Don