Hi - New member here.

Ive trawled these forums and (several others) to see if I can find a solution to my problem, but nothing. I'm hoping that you guys can help as there seems to be a lot of expertise on here.

A few weeks back I replaced the hydraulic hoses going to the latch of my 2003 XK8 convertible. Everything was working fine for about 3 weeks. Then one day the roof would not open. I could hear the pump straining. I managed to open the roof manually using the Allen key and turning the valve off. I could manually open the latch, then go back to normal operation and the roof would go down when I pressed the button. Similarly the roof would come up, but I then had to manually operate the latch. Rear quarter windows went down and came back up, along with the chime sound. I checked all the microswitches in the latch area and compared their operation to the TSB and they are all fine, also the fluid level is where it should be. It appeared that the latch was constantly trying to close and not open. My attention then focussed on maybe the latch solenoid on the pump may have stopped or at least got stuck. I checked with an oscilloscope that the SLC module was attempting to drive the solenoid (which it was) and the solenoid had a DC resistance of 11 ohms. This compared to the roof latch next to it. However now what has happened is that the latch is solid. I cant open it manually, and I am not able to open the roof manually. The roof will open and close when I press the button still. The rear quarter windows wont shut but that is because the roof probably hasn't fully closed, and neither is there a chime.

Today I removed the plate where the latch is to see if there was something mechanical that had got stuck. The mechanism is fine, as I can disconnect it from the ram and I can move it. The ram itself is fully extended and when I press the roof button I can see it moving a couple of millimetres. Even in manual mode the ram will not budge. So I'm either looking at a latch solenoid that is permanently on, or the RAM has failed or both? I'm stuck as to what it could be.

Sorry for the long post, I wanted to get as much information out there as possible

 

It could be that the roof system is confused. Open the roof and park the latch and then do a hard reset. Turn the key on for 10sec then off for another 10sec. This gives the computers to talk to each other. Start the car and press and hold the close button until the roof had completed the close procedure.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

I thought that at first. I even disconnected the battery for 3 days to give the vehicle a hard reset. Ive had to disconnect the latch from the ram for now so that i can close the roof. With the ram fully extended i couldnt move the latch manually.

 

If I understand correctly all the testing you've done, we know that the ram controlling the latch will not move either with the electrics engaged or, more tellingly, even when the petcock is opened and the hex key is used to drive the latch manually. That really leaves only two possibilities.
- the ram itself is seized or blocked from moving in some way.
- a latch hose is blocked.

If you're willing to maybe sacrifice a little fluid, we could distinguish between the two possibilities this way:
with the latch connected to the ram, petcock open, crack open a bit each hose connection at the ram, one at a time. Try (gently!) to operate the hex key in both directions. If no or little fluid tries to escape in both directions, the ram is seized or blocked. If no fluid tries to escape in just one or the other direction then a hose is blocked.

Good luck.

 

Thank you for the advice.

That is similar to my next plan. I'm going to undo the pipes to the latch ram and see if i can move it. If i cant then im going to see if i can release it with fluid or maybe WD40. If the latch is seized then I'll source a second hand one on ebay and I have found a company who can refurbish my latch in the uk. I'll.swap.over latches when I get it back. If the latch moves freely then the problem must only be in the latch solenoid in the pump. So I will replace that with a refurbished unit.

I'm.learning so.mich about this roof lol. Being and Engineer helps though.

 

That sounds frustrating, i wish i had an idea

 

When the petcock is open, the electrics are out of the equation. A solenoid could not impede fluid flow, or movement of the ram / latch. With the petcock open, only a blockage somewhere or a seized or stuck ram / latch can do that.

Being an Engineer helps me too most of the time, but there is that tendency to overthink stuff ...

 

Hi Guys - an update.

Ive removed the latch tray and removed both pipes to the latch. The latch moves freely, so that is not seized.

However when I press the switch to raise or lower the roof, fluid only comes out of one pipe and not the other. I can only conclude that the solenoid that controls the direction of the latch (inside the pump) is stuck in one position - presumably closed as the latch wont lift. If the hose was blocked, then I would expect fluid to come out of one pipe when the switch is pressed one way, then nothing when pressed the other way.

 

I feel certain of this much but will think about it more (it's been a while) ... with the petcock open the pump is out of the loop, so to speak and so the solenoid positions do not matter.

I believe you've reported that the latch cannot be moved manually when the petcock is open. I don't think a solenoid issue could explain that.

A test: Disconnect the latch hoses at the pump. Immerse them in a container of Pentosyn fluid. (Do not connect the hoses together; the flow rates in them are not equal because fluid accumulates in the latch ram when moved in one direction, is removed from the ram in the other direction.)

Can the latch be moved back and forth with the hex key with this setup?

 

The pipes are now empty of fluid and also the reservoir is low (below the line). I can now operate the latch and roof also manually, as I now believe there is no fluid in this part of the system.

Looking at the petcock that is between the reservoir and the pipes and solenoids (albeit only just). When I removed the pipes from the latch, fluid only came out of one port of the latch (the one nearest the piston). This would tie up with my original observation that it appeared the latch was always being driven to close and no movement to make it open. Im tempted to remove the solenoid to see if it operates, but I have no idea what is attached on the other end,

Im gong to take a risk and buy a reconditioned pump. If it works great, but if I still get the problem then at least I have a reconditioned pump lol.

 

Good luck with it. For your sake, I hope I'm wrong on this one.

The test I proposed requires that there be fluid in the hoses. If only air is in there, the latch could still be moved manually with a blockage, as it would just compress the air in a potentially blocked hose.

While waiting for a new pump you could try my test or swap the solenoids to see if that changes anything. (Be VERY careful with those solenoid electrical connectors!) Let us know please how it all works out.

 

ok - so lets say the pipe was blocked. How would I clear it? Also the latch always appeared to go in one direction not the other, a blocked hose wouldn't cause that surely?

What I didn't mention, as it only just occurred to me, about a year ago the roof wouldn't open as the latch wouldn't come up. After a few tries it eventually did. I assumed it was just sticking and so I grease the pins that lock the roof down and has been fine since. Wonder if that was the start of it?

 

ok - more updates.

I went a bit extreme here. I removed one pipe at a tome from the pump and operated the roof switch. There is fluid coming out of both exits of the pump. Hence, you are right. Looks like a blocked hose. FOrtunately I know which one. Now how does one unblock a pipe like this?

 

Just a few thoughts ...

When the petcock is open, I have re-convinced myself the solenoids cannot affect any testing we do outside the pump. For example, petcock-open we can with the hex key cycle the latch open/closed and back again. If the latch solenoid were in play it would have to be set for flow in one direction or the other, but not both.

I don't feel like I see your situation clearly, but if it were my car I would to this:
- confine testing to petcock-open for starters until we know the state of all the hydraulic stuff
- get some Pentosyn, and do the test I mentioned earlier. Repeated back-and-forth cycling of the latch should eventually purge the air and then we'll know if a hose if blocked, and if so which one.
- if there is a blocked hose, I'm afraid I don't think it can be repaired.

Good luck. Keep us posted.

 

The solenoids do not change the direction of the oil. They are just on/off valves. They are normally closed (by spring load)
Normal opening sequence of the roof:
1: Windows go down
2. Pump starts
3. Latch solenoid opens and direct oil to the latch cylinder
4. Pump stops and the Latch solenoid closes
5. Pumps start again - in the opposite direction! - That is actually what decides which way the oil is flowing.
6. Lift solenoid opens and roof opens
7. Latch solenoid opens and the latch closes
8. When roof is fully open and the latch is closed, the pump stops and both solenoid closes.

The oil that this system used on the earlier models was known to cause problem after several years. If it could be so bad that it actually clogged a hose, I do not know.

 

Hi All.

Its been a while but thought Id give you an update....

The roof is now working. The issue was staring me right in the face!

I found a company here in the UK about an hours drive away who specialise in convertible roofs. They claim to be able to fix any problem. I booked the car in and went down there. They spent a good few hours on the car and told me that after a lot of diagnostics, one of the pipes was blocked. They said they tried to clear it but couldn't which led them to believe the pipe had been snagged somewhere along the way. I thought this odd as it had been working fine for a couple of weeks. They said that I would need to bring it back for 2 to 3 days for them to get to the root cause of the problem. While they were putting my car back together, it hit me where the problem was most likely to be.

Lets go back a few weeks...I went to a car show and everything was fine. Afterwards when cleaning the car ready for my next show the following Sunday, I noticed I hadn't tightened up the passenger seat - it was actually loose. I tightened the bolts up. One bolt, front left, wouldn't go tight and eventually I rounded the head! Anyway, two days later the roof isn't working. I didn't for one minute connect the two. After being told the pipe may have been snagged, I suspected that a pipe had slipped under the seat and in doing up the bolt had pinched the pipe.

After coming back from holiday, I decided it was time to investigate. I managed to remove the bolt, using a combination of a drill and a centre punch. Low and behold there was a pipe under one of the seat legs behind the bolt hole. Crossing fingers I managed to free the pipe, turned the petlock valve back on and hey presto roof now works. Happy bunny

Thanks everyone who replied and tried to help. I learnt more about the roof than I knew already along the way