I know you asked Doug for his opinion, but I also have an engineering background, and thus have generated my own 'theories' about the hydraulic failures. It is twofold..

In warmer climates, the heat affects the lines AND fluid by hardening the rubber hoses and aiding in the solidification of the fluid. One reason I think mine (5 yrs old) lasted a bit longer than Dougs (only 3), is perhaps due to the fact that mine was operated frequently (as evidenced by the significant wear areas on the top). In any machine, the fluids, when circulated warm up and retain its fluidic properties longer. If the fluid sits idle for long periods, it can solidify and then when needed to move within the hoses, cause higher pressures in the system, resulting in failures of the hoses if they are not strong enough. The fluid itself, with the heat affecting the hoses (especially in that top spot where the break occurs), contributes to the problem.

My next question would be to my service advisor... that if we can perform a bleeding of the system and replace all of the 'aging' fluid, could we prolong the life of the hoses, though not forever obviously?

 

My background is really structures and not hydraulics but it seems like the problem area for the system used on the XKs mostly ends up being at the latch area and I suspect it is most vulnerable at the fitting where the hose connects to the mechanism. Most of the posts on this and other forums regarding this problem indicate oil leaks in this specific location and I do not know if other areas are as problematic. The latch area of the car is subject to the worst combination of mechanical and environmental exposure such as vibration and heat when in the sun.

My guess is that there is always some pressure in the system but that the most pressure comes with opening and closing of the top.

Doug

 

Just another thought on this whole convertible hydraulic hose leak problem. Similar systems in any automobile are under much more intense stress demands than the convertible hoses. For example, we have brake lines under pressure that are exposed to constant and severe road vibration, and what about power steering hoses in the engine compartment that are exposed to vibration and heat. If these can be made to work without chronic leaks and problems then how is it that the same could not have been done with the convertible system hoses? Just asking.

Doug

 

Gentlemen I hope that you will forgive me for participating in your conversation.

After replacing my hose I noticed that the failure was at the connection to the hose www.gusglikas.com/autorepair.htm photo#12 on the hose repair page. I think a survey on the causes and where the leaks were would be a handy thing to have. I suspect that the hose to the connection to the fitting at the latch is the problem as mine was. I am sure that the heat has a little to do with it making the hose pliable and loosing the firm crimped connection when hyd pressure latching is applied.

Many years ago when I worked on aircraft we had heat shields that would reflect the heat away from critical devices. If we knew for certain that most failures were at the fitting I think a better fitting could be applied and possibly be relocated or shielded away from the heat or vented. The area that the hoses are in is all painted black inside and out and if you ever owned a black car you know it will get plenty hot. Given the time and the information directing us to the causes it could be resolved.

 

No problem gus, you've been down that road already, so your input is greatly appreciated. You have at least, gutted your own car so you have more details about the system than most of us who just got the repair/replacements and let the dealer do all the work. I think I did see your leak in the photo you mentioned. Black...like a little oven up there I suppose. Doug's may have been the exact same location, though he may not be able to tell you for sure.

Mine never actually blew, though the ram was leaking and it was moaning horribly...possibly on the verge of eruption somewhere. I'm glad my service guy took a proactive approach and didn't actually wait for the failure to occur.