When I bought my 2006 XK8 three months ago, the top did not fully lower into the well when opened; I know this because I can tell from pictures the dealer took. (My friend and advisor pointed out to me that my tonneau cover should lie down more than it does.) Sure enough, the corners of the folded top protrude a full inch higher on my car than on his (4.75" versus 3.75"). The top opening sequence seems to be normal; everything sounds good, it's smooth, no error messages, and the chime sounds when the top is fully folded--or at least when the system thinks it is.

After I haad my hydraulic hoses and top latch cylinder replaced with hoses from Top Hydraulics and a rebuilt latch cylinder from them, the latch claw would not fully extend. It almost does, but not quite enough to engage the top bail and pull it down; I have to reach up and push the claw a little bit with my finger to get it high enough to accept the bail--maybe 3/8". The mechanic who did the work does not know why this is happening. He says the hydraulics and electrics are all fine. (He said the rams are fine.) Something, however, is not quite fine. In both cases, a component is not fully opening or closing as it should.

I suspect that in order to diagnose the problem I wil have to find another shop experienced in these tops, since there are so many components to the system, but I thought I would inquire here and see if anyone has any thoughts on what it could be, in case it's something simple that I could take care of myself. (Sometimes it is.)

 

Top Hydraulics was really great when I dealt with them. You could see if they have any thoughts about what’s maybe not right.

 

I was in comm with him a few weeks ago but he disappeared; I'm sure he's quite busy running that company but I'll get back up with him and see if I can get a response.

 

Check the fluid level at the pump. It must be at the top embossed line on the tank.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

I checked it last night. It's at the bottom line. Petcock is open, no visible leaks.

 

Sounds like air in the lines

 

The roof system is a self purging system pushing the air out of the lines and equipment and replacing it with fluid. Fill the tank to the top embossed line and then operate the roof a few times and check the level again.

 

Gus, as that would only cost me 42 bucks for a liter of Pentosin and require no disassembly of the car, I am most amenable to trying it! Thanks.

 

I know this system better than most people. For supporting information go to my page.

 

Update: e-mailed Klaus Witte at Top Hydraulics again the other day--he answered promptly and thoughtfully and had a hypothesis which I sincerely hope is incorrect, though it sounds completely plausible. As my knowledge is not sufficient to paraphrase with confidence, I'll just include what he said here.

"Here is the hypothesis: Imagine there was a fragment of a decayed seal that made its way back into the pump but didn't make it through the screen at the return port of the solenoid. When the new lines and cylinder were connected and the top was first used, there was a rush of fluid into the hoses and the piece of debris made it into the bottom hose. Once the debris reached the end of the line, it acted like a plug and blocked flow once it was fully pressurized. When it is not under pressure, it won't block flow because it is not a perfect plug.

Here is the suggestion to prove whether the hypothesis is correct: Swap the hoses on the cylinder end and on the pump end. If this changes the symptoms, then you have a plug in what used to be the hose on the bottom of the cylinder.

Here are the options if the hypothesis is correct:
It is unlikely that you will be able to get the plug out of the hose, so at that point, there are two options:
1) We send you a replacement hose free of charge. The downside is a lot of labor to replace the hose.
2) If you still have the hose pulling tool that came with the hoses, then you could play a neat trick that I hope I have thought out properly: push the bladder out of the tool, so that it permits flow to go through it, then connect the two front hose ends that go in the cylinder. Wrap a rag around it, zip tie the rag to both hose ends. If you now activate the pump such that fluid goes back to the pump in the plugged hose, then fluid from the clear hose will push the plug all the way to the end of the hose. If you push the button too long and let the pump run longer than a second, then the plug will likely block flow at the pump end of the blocked hose and pressure will build up, which may result in a serious leak from the hose pulling tool. If you have swapped the hoses, then the plug would be moved to the pump end when the cylinder tries to extend, meaning when the latch comes out of the windshield header. Thus, the position would be with the top down and the front latch closed, where you push the button to close the top. Let the pump run only for a second or two. The plug shouldn't do any harm on the pump end of the hose because the hose has more volume than the displacement of the cylinder. Thus, the plug should travel only about a third of the length of the hose and back the same amount once there is no air in the hoses. The latter (lack of air in the hoses) is why I suggested moving the plug with the fluid from the other hose."

There's no way I'd try to do this myself; I am going to ask my mechanic if he still has the pulling tool, and if so, get it back from him. I think my next step is to start calling recommended specialists.

 

Topped off the reservoir with Pentosin yesterday. No change in top behavior.

 

The petcock valve should be closed which is turned fully clockwise. Have you tried raising the top, then opening the valve (counter clockwise) and lowering the top manually?

 

Yes, but perhaps I need to press down on the tops of the lift rams to finish releasing the front of the top from the claw.

 

It is very easy to swap the latch hydraulic lines at the pump.
The OEM lines have an F printed on one of the hoses to match to the fitting when the new lines are installed.

I always take note on what line goes where!!!!!!!!!!!!!

 

So, when you open the valve and lower the top manually, the top is still partially raised?

 

I haven't lowered it manually yet. It's been raining all day.

 

Yes that wouldn't be too hard but the header end is a no-deal.

 

The header end (latch side) has the hoses VERY offset if they are made correctly at the top hydraulic facility.

The pump end are not as obvious except the circled F on the OEM.
Was the top hydraulic hose set marked?

It's been a really long time since I installed a set of the aftermarket hose set.

 

Good question. Haven't looked closely at that since I wasn't intending to mess with them. If there's no resolution before then, and a professional wants to try Klaus's solution, I'll take it to them at that point. That's as "invasive" as I'll go, though. I've already spent $2,200 on the hydraulics and I'm not going to have someone pull a hose at this point. Not worth it.

 

I'm pretty sure the circled F hose goes on the top (upper) pump fitting.
The unmarked goes on the lower fitting.
If one is wrong at the latch, you can just swap them at the pump.