A few weeks ago I bought a 1998 XK8 with very low mileage. The car’s in really great shape and runs like a dream but we’ve always had an issue lowering the convertible roof. I’ve read a number of the entries in the forum dealing with convertible roof issues but haven’t found anything that completely matches my situation.

I take the car out of the carport, engine running, in park, hand and foot brakes on, on level ground and press the roof switch. Everything cycles – the audible sound triggers, the back windows go down, the front windows slip down slightly and the pump engages – but the roof won’t open. I repeat this process up to 5 times and eventually the roof goes down. Sometimes there’s a ‘convertible not latched’ warning, but pressing the button again clears it. I notice however that, if I leave the car in the sun for 30 or 60 minutes, the roof goes down, first time, no problem.

I obtained a copy of the Jaguar notice 501-33 ‘Slow Operation/Erratic Latching – Convertible Top – Repair Procedure’ from a friend. The VIN number for my car is in the range mentioned in the notice that was not filled with Pentosin CHF 11S. So, after a conversation with a mechanic recommended by other XK8 owners, I had the hydraulic fluid changed about 10 days ago since this seemed to be the logical first step. This has not improved the situation.

A couple of evenings ago I took the car out and had the usual problem retracting the roof. It did eventually retract but, as it did so the latch in the roof pulled itself out of the hook above the windshield with a bit of a judder. We had noticed that the latch seemed to be sluggish on other occasions and the mechanic lubricated it when the car was in the shop.

We went for a drive and when we returned the roof would not close. Once again everything cycled but the roof would not even begin to close.

The following morning I went through the manual procedure to close the roof. I turned off the valve on the pump and put the allen key in the slot on the windshield ready to go. The roof came up by hand with no effort – but the latch on the windscreen would not move despite my putting pressure on the allen key. I didn’t want to force the mechanism so I put the roof back and turned the valve on the pump back on.

I’m looking for advice on my next steps……..

 

A few things... With a flashlight handy, pull the right side trunk carpeting away and verify the fluid level is at the maximum level. I know you just had the fluid either changed or added to but it doesn't mean you don't have a leak somewhere else. While you are there, take a look at the hoses and under the pump for any oily residue and report back. Making a heavy assumption here... Another thing is that it's possible that if it was the original fluid and being that old, it's possible that the fluid turned to a jelly like state and causes restriction in the system and also may require a bit more fluid flushing.

 

Let’s start with the roof not closing and the latch not moving. With the petcock open (counter clockwise) all the hydraulic pressure should be off the latch and rams. With the fact that you can close the roof manually tells me that the hydraulic pressure is off. If you are unable to move the latch manually tells me that the latch or the linkage is in a bind or it could also indicate that the fluid is clogged and will not release the pressure. Note that was the problem with the old fluid. I would open the header cover and look at the linkage and the roof latch ram to see if it is clear. It is entirely possible that the ram is dry and in a bind. Spraying it with WD40 could free it up but because it is retracted it may no.

Now to talk about pushing the button several times to make the roof operate is not a good thing. What it does is confuse the computers and then it does not know what to do next and will shut the system down. If the roof is operating slowly you should lubricate the lift rams with WD40 when extended and open and close the roof manually. The rams have several seals to keep the fluid from leaking out and the outside shafts get dry. Now most people do not like WD40 but it is a great cleaning agent and lubricant but if you are not satisfied with it use a good silicone spray AFTER the use of WD40.

 

Thanks for this, I'll check the fluid level and under the pump later today.

 

Gus, thanks for the advice. I'll do as you suggest. It may take me a couple of days to get to it, but I will do it.

 

Just a thought. In case it is the computer you have confused why not disconnect the battery overnight to do a reset? An hour or two wont do the job has to be longer.

Of course you will have to reenter your radio codes and reset the windows but it might be worth it.

Hope it helps

 

frankc, an interesting thought, many thanks. I've disconnected the battery, I'll connect it again in the morning and we'll see what, if anything, happens.

 

Addicted2boost, many thanks for your help. I've just checked the fluid level, it's mid-way between the 2 marks, which is interesting. The hoses seem fine. There's no residue of any kind under the pump, it's nice and dry and clean.

 

A hard reset is not going to harm your car if it is done correctly what in fact it would probably be the right thing to do for the entire car. When you perform the hard reset be sure the roof is open and the latch is parked (closed).

Your pump being low on fluid could be because of air in the system from changing the fluid. This system is self purging and it will take a few operations to get all the air out. Just keep an eye on the level.

I still have a concern on you not being able to operate the latch manually.

Link to Hard Reset JagRepair.com - Jaguar Repair Information Resource

 

Gus, once again many thanks for the advice. The procedures on jagrepair.com are really great, the illustrations are excellent. I'm very concerned about not being able to operate the latch manually too. I'll let you know how the hard reset goes.

 

Frank, unfortunately the hard reset has not changed anything. Fluid levels as before, hoses look OK, nothing under the pump, still can't operate the latch manually. I'm running out of time - and skill - so I'm going to take her to a chap who has been recommended by several other XK8 owners.

 

Disconnect the 2 hoses at the pump that you can see from the trunk and remember what hose came from what fitting then try to move the latch manually. Note put both hoses in a container to catch the fluid.

Gus
www.jagrepair.com

 

Gus, my apologies I thought I had copied you on the email to Frank. You obviously picked up on the fact the hard reset didn't move the situation forward. I'm hoping to take the XK8 when we do a road trip next week to visit our grandsons in California. So I was running out of time and decided to take her to a chap who had been recommended by several other local XK8 owners. He has done a little work for me already and I was impressed by that. By the way, I circulated the jagrepair web site to the other XK8 owners in a club I belong to and I see Brian Collings has contacted you directly. Hope you don't mind.

 

Not a problem.

 

Jim, can you update this thread once your source (hopefully) gets it worked out?

 

I apologize for not bringing everyone up to date with the solution but it took until November to get the roof fixed. The delay was simply caused by bad timing and poor weather (I couldn’t always get it in when the shop had time because the roof was stuck open and it rained a lot). I also wanted to prove to myself that the fix worked and I've only had the car out twice since I brought it home in November because of the winter weather.

The hoses from the hydraulic fluid reservoir to the windscreen latch were clogged. We replaced them and refurbished the cylinder for the latch at the same time and the roof is now working well.