Over the past year I have worked endlessly to provide a solution related to the problem of the rupturing hydraulic hoses for the xk8 convertible top. Several months later after receiving many hoses I worked to develop a hose that would accept the pressure and temperature. Soon after I received a latch that had evidence of the seal being dislodged causing a leak. Shortly after that the lifts were failing at what I thought was an alarming rate. I began to think that several other latches were failing just did not know how many or why. Well at the same time Tom (TestPoint) had a pump that he was willing to give away to a good home. Well I did all I could to get my hands on it and in a few days I got it in the mail. During that time I had several conversations with Walt (Walt Nuschke 00XKR Conv) about the pump and the new findings related to the seals in the latch and lifts. Seeing Walt was better qualified in the evaluation I sent the pump to him. You can see his findings on my page, I will provide a link below. Walt has since developed a device to be installed at the pump that will reduce the operating pressure to the entire roof operating system. We feel that this reduction in operation pressure will dramatically reduce and in most cases eliminate the frequency of hose, latch and lift failures. Because we are unable to predict the life of the existing system in your car we are reluctant to say you will never have another leak.

I am so confident about this device I installed it in my car! I am also going to end my quest to finding a solution to the hyd hose problem because this is it. I want to thank everyone for their input and patience when dealing with me. And thank you Chick & Ron for the hose and Tom for the old pump & Walt for the Hydraulic pressure relief valve and the many people that provided parts for evaluation!

http://jagrepair.com/HydPressureReliefValve.htm To see the pressure valve and how to get it and links to the hose evaluation, hose replacement and new hose. I am not making a penny from this product. I am however, placing this information for the person that wants and needs it.

A great deal of unselfish time and effort went into the research and development of the roof operation information that was used in the design and development of the new hose and new pressure relief valve.

When I took this project on I told those involved I would stay on it until the end and I did just that!

This post should not be taken as an advertisement in any way. It is to say that this project is completed.

Gus

 

Great job Gus!

Couple Comments:

The graphs in your excellent documentation relative to time do not appear to be consistent. How has the approximate 35% reduction in pressure affected the open/close time from the 20 second standard operation?

You might point our that ordering information is located on your web site as it is easy to miss?

While I am aware of Walt's credentials in the hydraulic business from his posts on the subject and the links to his web site, perhaps it would be reassuring to the members to post them here.

 

One additional comment:

The reason I got into my first XK8 was that the previous owner had torn the connector off the pump valve solenoid trying to disconnect the wires. Staring at a $2400 replacement cost (and several thousand of other backed up repairs) he dumped the car cheap.

Thank goodness for recycling yards!

Point being: Be careful removing the electrical connectors

TightWadTom

 

Gus,

A question. I have had the hoses recently replaced in my 2005 XKR. This was done at the Jaguar dealer and, presumably, the new hoses represent the best OEM replacement available. So would it be adequate to install the pressure valve kit and keep the existing hoses or is it also necessary to installed the improved hose kit that you had also worked on?

Also, about how long would it take a reasonably mechanically inclined person to go through the pressure valve install?

As a totally different aside, I am in need of one of the plastic clips that hold the allen key to the metal shelf where the pump is mounted. Do you happen to come across any of these?

Thanks,

Doug
Los Angeles, CA

 

I installed the valve in mine and I had replaced my hose a few years ago with a Jag hose. I did this to extend the life of the hose, latch & lifts. As for the most recent hose Jag offers, keep in mind it is from PowerPackers and they will not talk to us on the issue. And I have several of the hoses in my shop that have failed.

The total install took 40min. I was photographing as I was going along and what I did was put a few tools in my bag and installed this valve when I was in OC Md. Between rain showers. With my photos on how to 30min max.

As for the clip! I did try to find one for someone but was unable to do so. I did find an online shop that sold clips that came close to what you need. I can look again if you wish.

Gus

 

Gus,

Please do let me know if you find some similar clips.

A couple of other questions regarding the pressure valve. During the installation, is there a risk of getting air in the system that then requires a purge? There was no mention of this during your detailed install so I suspect the answer is that there are no requirements for purging the system. Also, I expect that the process if totally reversible if the top performance with the valve installed is not up to snuff? I guess the hoses from the pump to the check valve are still seeing maximum pressure but these are easily replaceable and could serve as a "fuse" to protect the rest of the system.

From what I see it looks like a decent solution and kudos for all the work. If we can get a bunch of folks on the various Jaguar forums to get on a list to buy a kit, is there a chance of some group discount?

Doug

 

I need to get the exact info from Walter but I was unable to see the difference when I operated mine.

 

good stuff

 

The system was tested to find out what pressure is required to operate the roof. This involved taking a pump apart to find out how it works, installing a pressure sensor in the system, and coming up with a design that can be easily installed DIY. The relief valve kit dumps any flow that occurs above this pressure back to the tank. The system does not have a built in pressure relief so when the cylinders hit the end of travel the pressure builds to the maximum that the pump can deliver. You can see this in the graphs taken from the data logger that Gus has published. The excessive pressure is 500-600 psi above what is required to operate the roof system.

My company is buying the calibrated valves in bulk from the factory. If for some reason the roof does not operated properly the valve can be adjusted. The hoses are rated at 6000psi and are the highest quality possible. Nothing was spared in that regard. A full DIY instruction will be available on our web site later today. This is all just hitting the street.

The operate time is not affected. It takes around 3 seconds to open and about 17 seconds to close more or less. The graphs came from my car and some variability is to be expected based on temperature, battery voltage, and phase of the moon.

The system self purges so there is no need to bleed off trapped air. Very little oil is lost during the install if the instructions are followed.

There is no need to change hoses unless the car has Nylaflow hoses to the latch. Nylaflow hoses were used up to a certain date when it was discovered that they fall apart in the high temperature conditions at the latch. The Polyflex replacement does not have this problem. This upgrade reduces the stress on the system by 33% so the hoses will be on easy street. I have been in contact with Parker, who made the custom hose for Power Packer, and that hose (product #363) has been discontinued. This means that the factory hose will not be available at some point very soon. Gus and I are looking into making a replacement available, but I doubt that a reliable splice hose will be possible, so only a full length hose will be feasible (in my opinion). The fittings must exactly match the dimensions of the hose (ID and OD) and the special hose used in the car does not match up with any of the commercially available hose fittings according to Parker. We have not been able to find a fitting that would be reliable for a DIY install.

Please feel free to contact me directly with any additional questions.

 

Thanks for the info. I assume the reference to 3 seconds opening is a typo or else that would be some lightning fast opening So what you are saying is that the OEM system delivers far more psi than is really necessary to do the job, which surely accounts for much/most of the failures that convertible owners are seeing. Any chance of a group purchase price if we are able to get a bunch interested?

Doug

 

We can give a discount for purchases of 25 as that is how the people that make the valve operate. If you want to do something like this let me know as we have dealer pricing available.

3.5 seconds is actually correct for the hydraulic part which doesn't include the windows going down. You can see this on the time axis of the graphs. Raising takes about 17 seconds for the hydraulic portion. The controller holds the pump on and the end of the cycle for about a second, which is where the high pressure damage occurs. At that moment, if you listen to the pump, you can hear it really straining. This is not good for the pump motor or the hydraulic components. What we are offering should have been part of the original system as it could have easily been built into the pump body.

 

Sounds good to me and definitely should be a great protective device to improve the longevity of the system. If you need 25, you can put me on the list. Maybe the moderators can create some "sticky" where interested parties could add their name?

Doug

 

How do I tell if my 98 xk8 has nylaflow hoses? I'd be interested in getting my name on the list of 25 to purchase one of the valve kits.

 

Look at the hose that is attached to the pump in the trunk of your car. When you pull the cover off you will be looking at the pump and two hoses that go to the roof actuator. See if it has a series of numbers on the hoses and post your information. Product# 303 is the first generation of hoses. You need to know that the first generation hose gets brittle and both the first and second generation hose will pull out as well from the 1600psi pressure applied. This valve will reduce this pressure without extending the duration of the open and close of the roof.

Gus

 

We have ordered parts to have kits in stock and some will be ready in 1-2 weeks. If someone wants to get together an order of 25 that gets shipped to one address then we can pass along a discount of 25%. I can't do this if I'm dealing with 25 individuals.

 

Wow, great job guys. That part/kit is going to save alot of jag owners alot of money. Its a fantastic idea, though not a guarantee, would be the first thing that I would buy when purchasing a used xk8/r convertible that had not had a hose replacement after failure.

I also put this modfiication kit in the FAQ sticky for new owners and such to find easily.

 

It also seems like a good thing for folks like myself that have had a recent hose replacement and want to avoid another!

Doug

 

Gus and Walt, thank you very much again for your continued efforts and support on this. I am a very recent 1999 XK8 owner and have gained much insight. I put my order in already for the valve. As I said, not having any trouble today with my roof but am trying to do everything I can to keep it that way. Still interested in seeing if anyone can help identify the hoses in my car so I can decide if I should replace as a preventative measure or put in the valve and hope for the best and fix on failure if and when that happens.

My hoses are marked as such: Powerpacker 1/87 DN3 MIN BURST 600 BAR 167/8
There is also what I assume is a date code on the connector of 07/98 and then on one hose there is a white band near the connector with the capital letter F on it.

Interesting that neither Gus or Walt have seen this particular hose before. Has anyone else? Just wondering if these are Nylaflow hoses or if they are the later series...

Thanks!

 

Based on the date of the hose it is the first generation hose. As for the white band on the hose that is a marker that indicates the position on the pump and latch. On my car it was the indicator identified the close pressure hose at the pump and at the latch. This prevents you from crossing the latch hoses when installing it.

 

My guess is that it is a Julian Date! I calculated it out for June 16, 1998 and it comes out to JD 167 and the year 1998.