I was driving my XKR one day last week with my son. We had just put the top up because it was unbearably hot outside. We had the A/C on and we thought that we could smell some gas fumes in the car. Later that night after it cooled off outside, my wife and I went for a top-down evening cruise. We both thought we could smell gas fumes during that drive, as well. When we got home, I started to close the top, but the top wouldn't close. You could just hear the whine of the electric motor when the raise top button was pushed, but nothing else happened. A ruptured hose, I thought, but no green shower from overhead console. It was late, so I just pulled the car into the garage for the night.

The next morning, there was still no sign of oil leaking from the windshield header. (Thank goodness, because the classic green shower happened to TPO last summer.) I opened the trunk and fumes were very strong. I removed the right bulkhead cover to check the hydraulic pump and there was green oil dripping from the top of the rack where the pump was mounted. Evidently, the Pentosin hydraulic oil has a strong chemical smell, similar to gasoline. That's what we were smelling!

Fortunately, the power amp and CD player were not touched by the oil. Through the plastic you could see that the reservior was low on oil. I couldn't tell where it was leaking from, for sure. I purchased some Pentosin CHF-11S, at O'Reilly's, added some to the reservior and had my son operate the top up/down switch. I could quickly tell that the hydraulic hose that goes over the top of the reservior had been rubbing on the brass fill nut, and the hose had burst at that point. I had a green shower in my trunk!

Does anyone have a hydraulic hose routing diagram showing specific hoses going from the pump to the other parts of the car? (i.e. Hyd cylinders and locking latch.) There is a local hydraulic house that can build a hose for me (I think!), but I would like to see what I am up against before I tear my car apart.

Thanks for any help!

Jon

 

Lucky escape!

Check this thread for hydraulic pump issues:

https://www.jaguarforums.com/forum/x...ulic+pump+hose

It also links to Gus' website where you'll find further information on the pump hose issue.

Graham

 

Thanks for the thread links, Graham. I also checked out Gus' website. I am impressed! Gus has volumes of information about convertible top hydraulics. Thanks Gus. I am still going though the threads digesting information.

One thing is for sure, it looks like another weekend project for me. This time inspecting and replacing a hydraulic hose or two. I'm also considering the pressure relief valve or pump resistor upgrade, to lessen my chances of future problems. I see that there is a lot of debate on the subject!

Cheers!

Jon

 

I believe the general consensus here on the forum is that once you replace the factory hydraulic hoses with the new-and-improved aftermarket braided metal-sheathed hydraulic hoses, you no longer need either the pressure-relief valve or the pump resistor assembly because the new-and-improved hoses are rated for much more hydraulic pressure than the pump is ever capable of creating....

 

Not exactly. The latch cylinder and pump also experience these higher pressures (not the lift cylinders though), so the pressure relief valve may be a factor in extending thier life (particularly the latch cylinder).

As for the merits of the resistor, I have said before all I am going to say on that topic.

 

If the original hoses on my '01 ever do fail, I would continue using a resistor with new hoses. Reason being, anything that lowers the peak pressure and/or the rate of pressure rise in the hoses can only help.

So who cares about rate of pressure rise? In all of our earlier discussions, in evaluating pressure graphs, we talked about peak pressure only. Everyone assumed that that number alone was important. I think we were ill-informed. The people who write the testing standards for hydraulic hose assemblies (e.g. ISO 6803), and who built the related test gear (e.g. Hydraulic Hose Test, Impulse Test stand, hose and Fittings test) recognize peak pressure AND rate of pressure increase as important metrics. All else being equal, a more rapid pressure rise imposes more stress than a slower rise. In fact, the rate-of-rise metric is so important that automatedd testers generally offer various waveforms (square, triangle, sine, ... ) and some even allow programming the detailed shape of pressure pulses when subjecting a hose assembly to testing.

If only peak pressure were important, they wouldn't go to all that trouble.

 

I finally got the replacement of the burst convertible top hose completed...and a bit more. With my heavy business travel over the past several months, I have been short on free time, so I took my car to my local indy shop for repairs. Here's what they found when they dug into the hose repair:

With the back seat removed to replace the burst hose that goes from the pump to the LH ram, an inspection of all the hoses and the lift cylinders was done. It turns out that all four hoses going from the pump to the cylinders were leaking and had to be replaced. They were deteriorated badly. I don't think that the hoses had ever been previously replaced. I went with custom steel braided replacement hoses supplied by a local industrial hydraulic hose shop.

It was also determined that the RH lift cylinder was leaking and I replaced it with a new cylinder, as well. The left cylinder looked fine, as it was replaced by TPO last year. The top latch cylinder/Hoses were inspected and found to be in good shape, as they were also replaced last year.

My indy shop did a thorough job, as they always do. I wish that I had more time to do it myself, as my wallet is now is quite a bit thinner. But, on the plus side, I have enjoyed some nice top down weather over the past few weekends. The forecast for tomorrow is for blue skies, a fall drive with Mrs. Growler with the car top down, high around 80 and great big smiles!

Cheers!

Jon