After replacing the front shock mounts on my new to me 2000 XK8 convertible, the next item of concern was the hydraulic lines to the front latch. Looking at the pump, the linse for the lift cylinders are obviously OEM and show the expected level of deterioration. The lines going to the front latch however don't have the black covering deteriorating like the others and there's a piece of blue tape on one, as if someone was identifying one line. Looking down from the right side of the car, I could see the lines and spotted a manufacturers date code of 02/2017 so that settles it...the prior owner had those lines replaced. Needless to say, I'm thrilled that job is off my worry list!!

 

If you read this up you will find the recommendations are.
Dont open or close the roof with the engine running.
Many have fitted a 0.1ohm resistor in the live to the pump to reduce the voltage to 8v and hence the pressure

 

When I acquired my 2001 XKR the p.o. Told me he had replaced the roof hydraulic lines 6 years previously due to the dreaded green shower. He also said he always has the engine running when he raised or lowered the roof. I continue this practice 3 years later, with no issues. I think the draw on the battery without the engine running is too much. What do you think?

 

Its only 20A but reducing the voltage reduces the pressure which reduces the chance of pipe failure.....your car your choice

 

Not sure if that's true. Extensive testing by another member showed resistor still resulted in a pressure spike. On the other hand, testing of the pressure reducer gizmo showed a considerable reduction of pressure. Do a search and you will find a plethora of posts about this.

 

Yes, as you said, about 20 amps. For those not familiar with the numbers, maybe worth saying that it's similar to the current drawn by the headlights. Operating the top with the engine off does result in a slightly lower voltage, slightly lower peak pressure.

Any of these systems -- stock, resistor, or pressure reducing valve -- will have a pressure spike as the latch is closed. It's about 1600 psi in a stock system and cannot be reduced below about 1200 psi or the latch won't work. A reducing valve can produce a lower peak pressure than a resistor, but a resistor makes the pressure spike more gradual.

I've never seen data offering proof that these mods reduce the failure rate of stock hoses, but I think it's a reasonable bet that they do. There was a survey done here years ago that suggested an improvement, but not enough data to say anything for sure. My sig. line below has links to xk8 convertible top mods that I worked on some years ago.