I now have joined the not so exclusive club of owners with the green shower roof hose leak. I installed the pressure relief valve when I bought my 03 XKR 1 1/2 years ago. I keep the car in the garage and only drive it about 5000 miles per year. I live in South Carolina, where it is quite hot in the summer, but I have rarely had my car out baking in the hot sun for very long. I guess I`ll be replacing the hoses this winter when it`s cooler out but I don`t look forward to doing the deed. I was hoping for better with the relief valve installed but....I will be glad to have new hoses and be done with this hopefully for good.

 

I had that happen after I damaged my hydraulics trying to take the top down with a hidden stainless steel coffeee mug wedged underneath the brackets. The cup won.

Sorry about your problem. Hope it all turns out good for you.

 

That is unfortunate news. Even a reduction in pressure, it appears, may not indefinitely prevent the leak at that connection. Just tell yourself you delayed it 1-1/2 years, it sounds better.

 

When you replace the hoses, use the kit from Coliflower to avoid those hoses ever bursting again.

 

I'm actually surprised that the cars with the pressure relief valves are still suffering from burst hoses. Think about it; the kit has only been sold for a little over a year. So a year ago those hoses were withstanding 1500 PSI. And now they can't withstand 1000?

If I had one of the relief valves, which I don't, I think I would adjust the screw to reduce the pressure to the point where the top would not latch, then gradually raise the pressure until it would latch. That way I'd be certain that the top was operating at the minimum pressure that would allow the top to latch.

 

i hope can that dont happen to me

 

The pressure the system puts out is 1600 psi without the pressure relief valve. It is unfortunate that the hose has not lasted longer, however, how long was that hose in the car before the valve was installed? If the hose was the original hose I would say it was stressed long before the valve was installed. In the case of an old hose it is just a matter of time. The valve will only delay the failure date if it is the original hose if it has been stressed.

Adjusting the valve is not what you want to do.

 

That's a good suggestion, IMO. In working up the resistor solution to the problem, I found that the minimum peak pressure that would operate my convertible top latch reliably was something north of 900 PSI. So the nominal relief valve setting of 1000 PSI is probably pretty close to the minimum for most cars, if my car is typical.

 

The pressure relief valve is adjusted to operate at 950psi +/- a few. Make no mistake it did not matter what reduction system you used it was doomed to fail it was just a matter of time if it was the original hose. Reducing anything lower is only going to deteriorate the quality of the roof operation.

 

I wish I knew what kind of hoses these are? din, sae or 100R spec and what end configurations...As a certified ( and certifiable) connector technician from Parker Hannifin I can tell you no hose will last forever, given decent circumstances with a quality hose I would expect 5 to 10 years life. But all it takes is someone to exceed the bend radius of the hose whether by mis handling or a myrad of other scenarios and that hose life is dramaticly reduced.

 

You are in luck! It is a Parker hose and I have a few hoses on my page. Link; To Parker Hose

 

Well, welcome to the club. I, too, installed the pressure relief valve, along with new hoses (guaranteed at 3000psi), a new actuator, new fittings, and a "partridge in a pear tree," and I continue to get occasional leaks. Get used to it, it probably won't go away.

 

Certifiable, you say. I can identify with that.

Given your background, I'm hoping you can you shed some light on these questions:

- How much of a role does temperature play in determining the life of the hoses in use here? There's some evidence that they fail mostly in cars living in hot climates.

- Same question for peak pressure. Experiments have shown that, in a stock car, the pressure peaks at ~ 1600 PSI for a few 10ths of a second while opening/closing the latch. Mods (electrical or hydraulic) in use by many guys here reduce that to ~ 950 PSI. Again, there's some evidence that failure rates with such mods are lower.

TIA for any insight you can provide.

 

Gus, intersting...I'm on vacation this coming week, but when I get back I'll call the Polyflex division and see if I can get the specs on the "363" hose, as I see nothing in any of the Parker online catalogs.

Let me preface this by saying my dealings with the Polyflex division are typically on ultra high pressure hoses...above 10,000 psi. But I do not believe this hose needs to be skived in order to be crimped, the fact that you said there was no cover under the crimp shell, leads me to belive it was skived. But I won't know if that's the case until I can get the specs.

I also noticed one pic you had stated it was from a 2000 XK8, what I'm thinking is the date code on the hose shows it as being produced in the 4th quarter of 03, which would make this particular hose not the original. Hard to tell from the pics but appears to have BSPP threads which would make sense.

Again, once I talk with the right person in the Polyflex division, I'll know more.

 

Dennis, heat certainly plays a factor in hose life, typically temperature of the media being conveyed. If that media, hydraulic fluid etc, reaches operating temps above what the hose is rated for, life will drop dramatically, typically you'll find they become very stiff and brittle. Ambient temp like we see in Florida in the summer I'm not so sure is a major factor as it typically affects the hose cover only. All the cover is there for is to keep the reinforcment braiding in place wether it be Kevlar or steel braid.

Peak pressure, once we know what the hose is rated for working pressure wise (and it should be on the layline) Parker generally has a 4:1 safety factor on thier hoses, so if maximum working pressure is rated at 1600psi, it will fail or burst at around 6400psi

But again, until I can get in touch with the right person from the Polyflex division and get some specs, I am just speculating. I'm more involved in the Heavy Equipment side of things than Automotive, but there is some overlapping.

 

watching and waiting on this CG......could be some interesting info here

 

One thing that seemed to play a factor in my hose failure was what appeared to be overtorqued connectors, resulting in some twist in the line where it meets the connector.

I wish I would have taken photos of mine, as they had not completely failed when I replaced them, the hose and jacket were still intact but the outer layer had started to become brittle and was cracking and had a slight bulge at the connector. A little bit of the nylon (or whatever material is under the jacket) fabric also appeared to have a higher twist rate than the material adjacent to it after pulling off more of the hose jacket and inspecting.

For whatever it's worth...

 

This might be of value in your discussions. I hope so.

The failures we're dealing with here are mostly at fittings where the hoses connect to a mechanism to open and close a latch located above the windshield. There is only very infrequent flow there, and when there is flow, it lasts for at most a few seconds. The fluid does not circulate; it's a back-and-forth system.

So: seems to me everything ... fluid, hoses, etc. ... is going to be at nearly the same temperature and that temperature can get to something like 150+ degrees on a hot, sunny day (from memory, not sure of the actual number). In fact, come to think, the flow in one direction will send into a hose fluid that has been sitting in the latch actuator mechanism, a big metallic block of sorts, getting maybe even hotter.

Don't know if this stuff matters, but thought I'd pass it along.

 

If I understand what you are saying, the fluid near the latch (not much there) is never exchanged with the rest of the fluid. What was near the latch last year is near the latch now.

Some of the other stuff I was reading sort of indicated that changing out the fluid periodically (even the latest approved fluid) would be of benefit. I have considered (but have not yet done) sucking out some of the fluid in the reservoir and replacing it with new. If I did that, it sounds like the new would never get to the latch. Hence, no benefit.

Does that make sense?

Jack

 

I think they would mix eventually, by diffusion, rather than by circulating the fluid.

One way to picture this: imagine the replacement fluid was dyed a different color, but was otherwise identical to the removed fluid. Would the dye stay contained in one area so that we would see a line between the old and new fluid? It would not. Eventually all the fluid would take on the same color.

How long would this take? No clue, but I bet not more than a few days for everything to be completely mixed. Another victory for entropy!