Yessir, replacing the spring gets you pressure reduction for $2.00. I keep a supply of springs on hand. Link in sig. line below.

This does not effect how fast the top operates. Pressures about the same in hot or cold weather.

(I agree ... be sure this or any system is working correctly before modifying it.)

 

Has anybody tried converting the top latch to solenoid or electric motor operation instead of hydraulic?

 

HELLO !!!!!!! is anyone at home ???

 

The 2007 and later redesigned XK has an electric drive.

It would be a pretty good engineering challenge to integrate an electric actuator into the old design as there is very little space in the header. The existing hydraulic actuator pulls down the claw with considerable force to lock and seal the top and it is physically quite small for the power it develops with over 1000 PSI driving it. Then, it would also have to be integrated with the existing computer controlled top control system which is split across 3 different multi--function electronic modules (the BCP, the SLM and the Driver door Module.)

 

There is, was there something you wanted?

 

WhiteXKR, the control signalling would probably be the easier part; either tap into the signal to the pump that causes it to pump fluid into the latch hoses, or put a pressure switch on the latch hose at the pump. It sounds like the physical latch would be the more difficult part. You could possibly mount a motor under the dash and run a drive cable to the latch...but may not be worth the trouble since the relief valve modification seems to avert the biggest issue.

 

This has been looked at and talked about long ago. If you are looking for a cheap way out replace the hoses the engineering and custom linkage would put you over the edge.

 

Not looking for any way out. Was just curious why Jaguar had not used electrics to begin with, and asked if anyone had tried that conversion. According to WhiteXKR, apparently Jaguar decided it was a better way to go with the 2007 MY. More of a thought exercise than anything else for our vehicles. I have already installed the pressure relief valve for my car. Sorry if I revived an old debate.

 

There is really no debate in that we all agree that the original system was severely flawed, at least to the extent that nobody seemed to give any thought as how to easily effect repairs once the hoses would predictably fail. Any logical person would see that having single hoses from the rear to the front versus pieces of hose interconnected with decent fittings results in horrible access problems. A vast improvement right off the bat would have been to have solid tubing brazed onto the latch assembly and then running down the A-pillar to hose fittings.

I guess the design in the XK150 vehicles wisely totally eliminates hoses running all over the vehicle from front to rear.

Doug

 

Rube Goldberg himself could not have designed a dumber system. As the local Jaguar dealership service manager once told me, there are only two categories of XK8 convertibles: Those which have suffered the green shower, and those which will suffer the green shower....

 

Never be sorry for good dialogue.

 

Jon,

He's got a point, but some reprieves are out there too ...
- the earliest cars had hoses that seem to last.
- UK and other cool-climate cars seem to avoid the green shower too. (I'm convinced it's primarily temperature.)
I've run two XK8s, both with original hoses, over an eight-year span now with no failures. (Knock, knock.) Just lucky maybe, but I have taken precautions.

Aside from hoses, I've developed a grudging respect for this system. The pump is bullet-proof; can't recall a failure reported. Similarly, the two flow-control valves (provided we're careful not to whack their fragile connectors). Beyond that it's hoses (criminal), three hydraulic cylinders (reliability in line with industry), and a few limit switches (same). The "Modules" which control this stuff seem quite reliable.

There are only so many things that go wrong. I can think of only one trouble reported here that didn't get sorted out (a previous owner had tried some creative re-wiring of components).

 

I would have had more respect for the system if the designers followed some basic fail-safe philosophy. Such as if you have a complex system with hard to get to hoses under high pressure then you should break the system into smaller easier to access pieces rather than confronting the task of running a single hose (did I say under high pressure?) from the trunk all the way up to the windshield header.

And, oh yeah, about pump failures I guess you didn't see my post about the pump failure I had. And at $2,000 a pop for the part, another idiotic design.

Doug

 

Since before 2008 when I joined this forum I have seen a few pump motors fail, several pump solenoids fail / broken many latch cylinders and lifts leaking along with failures and I am unable to say how many latch hoses and lift hoses that fail.

As for the cause in my opinion and research the hoses and seals were related and undersized for this application. Yes heat was a contributing factor but not the main reason for the failures, failures were reported in many different states and countries with varying climates.

So to say temperature is the major contributor to roof failures is incorrect you could say that temperature aided to a shorter life. Remember that the first set of hoses for this application are still in operation without failures so I would say that re-engineering by Jaguar/Power Packers to save money bit us in the ***!

 

I do recall pump motor issues --- wiring faults, brushes needed maybe -- but if there have been actual pump failures I missed them. (Some folks might not have looked further if the pump stopped running, and counted this as a pump failure. I don't know.)

I don't recall any control valve (solenoid) failures not caused by broken connectors. Can anyone cite one?

Whether temperature or pressure is the most important cause of hose failure cannot be determined by looking at failed parts and drawing an inference. We have to withhold judgement and let the statistics tell us. (Edwards Deming spent decades getting industry to understand this.) Of course there are some failures in all countries, climates, etc. With or without pressure modifying add-ons. What tells the tale is correlation. If we were to count up all the reported hose failures, and their circumstances, there's no doubt in my mind we'd find the strongest correlation with climate/temperature.

edit: Forgot ... the smoking gun concerning temperature is that the latch hoses fail much more often at the latch end than at the pump end. The same peak pressure exists in both spots, but temperatures differ greatly. The latch area gets much hotter.

 

I remember a pump being replaced at a dealer when the problem was that the pressure relief valve was not fully closed.

Like Dennis I cannot remember a single real pump/motor failure reported.

 

As an individual looking at the convertible top discussions and realizing difference of opinion take away from the fact we are all more knowledgable because some have gone the exta mile to find causes and solutions to our problem. Please understand how much we all can move forward with fixes on our cars because we know what each part is doing and how to either fix it ourselves or where to send them to be fixed.
As the cars are getting near the 10 year old mark and some 20, they are changing hands for many reasons and many buy them not knowing when or even if the hose, pump, ram or latch have been looked at. So what has gone before and why is really not the object, the biggest concern is how do we fix it and what can we do in helping it not happen again.
At present we have two methods of reducing pressure, several choices of hoses, rebuilt rams that are better than new and even a latch that can stand up to high pressure. The electrics are something to be handled with kid gloves and this will be a ongoing problem until someone starts to reproduce these connectors. Some are just buying Radio Shack plugs and connecting the wires on their plugs, works in many cases, but not all.
So, I'm just trying to say THANK YOU to Gus, Steve and Dennis07 for their work and concern, and ALL others that have given us their trails and errors, making us aware of what we will be getting into.
Thanks to all, and Yes, I'm getting ready to take the plunge. Wayne

 

Tom, we had 3 pump motor failures that resulted in a pump replacements that I have been involved with along with 2 maybe 3 coil failures not related to the plugs being broken and 1 clogged coil orifice in all the time I have been dealing with the system. A broken plug is one that you are familiar with.

 

The pump function that the motor drives in this system is designed like a rotary engine and is not like the pumps we think of or are familiar with. No I have not seen any failures in that part of the pump.

 

I read this too quickly last night. Ouch! That's a tough way to lose a good pump.

I think everyone agrees there have been no reported failures of the pump itself (unless we consider the motor driving it to be part of the pump; not an unreasonable thing to do). I may have pix of the pump mechanism, if anyone would like to see. Eccentric-ring based.

Can anyone cite post(s) describing control valve failures (other than broken terminals)? I can't seem to find any but have not looked all that hard.