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Slow Converible mechanism

2216 Views 9 Replies 7 Participants Last post by  Gus
I've owned my 2002 XKR Convertible for just over a year and I'm still thrilled with it. It's fast, pretty, agile and simply's a fantastic car.
With the arrival of the nice weather, I've noticed that the power hood has really slowed down and sometimes needs a helping hand in getting the roof raised back from the closed position.
Any ideas where I should be looking and is this a common fault?


Gareth Cooper
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The fluid that pushes the pistons up has gone to a jelly. Alternatively you have sprung a leak which is worse. Get some CHF 11S fluid and get it swapped. Check for leaks as the stuff is not pleasant if it gets in the interior. Happened to mine , most annoying when the good weather is here.
How difficult is it to swap the fluid yourself? Anyone know? Mine is working OK I think but at 10 years old is it worth getting it changed anyway?
I'll let you know when I've done mine. Should just be the time involved rather than anything difficult
Buy CHF 11S fluid from e-bay , £10.49 delivered. Put hood down and then release the pressure using the key on the side of the pump. Remove filler nut from top of pump. Using syringe with plastic pipe to reach into pump remove all the fluid. Once nearly empty manually raise the roof and lower a few times to empty the rams etc of fluid. Repeat removal step and raise/lower hood to ensure all the old fluid is removed. Rinse syringe in fresh fluid and discard contaminated fluid. Re-fill with fresh fluid to mark on pump. Manually raise and lower hood. Close key on side of pump to pressurise and use button to raise hood. The system is self purging so takes a few seconds to drive out the air before moving much faster :) Check fluid level and top up as needed. Takes about 30 minutes.
There are two main documented issues with the roof hydraulics. The first as previously mentioned in the thread is the fluid solidifying. This was a big problem on early cars but by now through the passage of time should mostly have been resolved. The way to check is the colour of the fluid in the pump, it should be light green.

The big issue is what is known as " The green monster " this is calamitous !

Apparantly the pressures delivered by the pump can be extremely high, especially in relation to the latch at the front which finally pulls the roof in to place. The hose at the latch is known to go, which then pumps green hydraulic fluid initially in to the overhead light cluster and subsequently in to the overhead trim and then down on to the gear shifter. It is not pretty. The problem is well documented by XK owners in Calafornia where they tend to get the roof down a bit more often than we do in the UK.

If this happens you are facing a major job, the whole interior of the car needs to be removed to replace the hoses. it happened to me exactly one week after I bought the car and cost me a grand to fix.

looking on the bright side, I would guess that you either have the gunge problem or if that has been fixed already then not enough fluid in the pump. Another possibility is that the bypass valve on the pump is partially open, which reduce the overall pressure.

One other possibility, when I reproofed my hood last year, the hood fabric became slightly stiffer, meaning that the load on the pump was increased to get up and down. I sometimes had to give it some help, but it's fine now.

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Good to see the instruction P700 - doesn't sound too bad.

In terms of the green monster, is regular use of the hood (ie putting it up and down) likely to increase the chance of this happening or reduce it? I can't figure which, if the fluid rarely moves there is more chance of the hoses suffering lack of lubrication and therefore seal failure, but the movement may cause the failure. Any suggestions?
I had the dreaded green shower a couple of,months ago it's generally where the pipe is crimped onto screw fitting above interior light fitting. It was when we had the good weather in March so the hood hadn't been used much but not sure if lack,of use was the cause it is however because of the very high pressure in the pipe to the roof latch that causes the leak. If you do a search you will see lots of articles on a pressure reducer you can insert into the line or dropping the voltage to make pressure less. Also raising hood with engine off means less voltage apparently so less pressure.

By the way while a long job replacing the pipe is not difficult have to remove trim, seats and lift carpets.
Well I suppose if you never move the roof, it will never leak (LOL). I can only give my experiences but any car mechanism will seize if it is not used. I once laid a car up for a few months and it was the worst thing I ever did.
I changed the fluid on my XK8 over seven years ago and have always operated the roof at least once every week, rain or shine. I also lubricate the pivot points on the mechanism arms with light oil because these can get stiff and increase loads on the hydraulic arms. So far I have never had a problem with the mechanism and it still retracts/latches at the same speed it has always done. Bear in mind that as my car is almost sixteen years old, I don't think I can complain with anything failing. Original Nikasil engine (although new top tensioners) but refurbished gearbox, a few suspension bushes (now polybush) - but everything is original. Best and most reliable car I have ever had.
If your car is a MY 2002 then the fluid in the hydraulic system is CHF 11S (green in color) Change it if you wish but it is a synthetic and do not need to be changed. As for it operation slow I would ask if the engine was running when you were operation the roof. I have a great deal of information related to the roof operation and how it operates - Jaguar Repair Information Resource . The roof pump requires a battery fully charged and in good health.
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