The top was very sluggish on my recently acquired XK8. So I read all of the posts to see where to start looking. Learned a lot and got an understanding of how it is timed with the latch and windows and basically if it snoozes you loose!
When I checked the pump I found the fluid way down and figured that was the first place to start. (Low fluid (not out) in a mower I have also affects its operation.) Got a tin of the Pentosin CHF-11S at my local AutoZone (Took awhile to find and was not listed in the computer!) for $23.95 +tax.
Was going to make up a syringe based affair as seen in some other postings. I remembered I had some old Nalgene squeeze bottles (8oz) that would do the job and since I was missing the nice nozzle that goes with them I just added a piece of rubber tubing that fit the bottle outlet and then a 1" length of hard plastic tube as a tip.
Put in about 6oz of CHF and lubricated various joints and the rams with silicone spray. Rechecked fluid level a couple days later and multiple cycles of the top and added 2 more ounces. Working great! Raises or lowers in less than 20 seconds.

 

Be sure to fill it to the top embossed line on the tank.

 

if you have a bit of clear medical tubing you can siphon directly from the green can into the reservoir without having to remove the pump from the car.
Really easy and if you use clear tubing you wont get a mouthful of green fluid.

 

Gus, do I remember correctly, the fluid level changes roof open/closed? If so which position should roof be in for proper reading? Thanks, John

 

No that is incorrect! This system is a Push/Push system and what goes in to open the roof goes out and back into the tank. Just fill to the top line of the tank no matter the position of the roof. I know this is different than the owner’s manual says but I have tested it myself.

 

Johnken's question is on point.

The fluid level in the reservoir is higher with the top down vs. with it up. This is easy to verify if you have a grease pen or a Sharpie handy. Also it has to be true from simple hydraulics ... the rams hold more fluid when expanded (top up) vs. when contracted (top down) and this difference has to show up in the reservoir. Someone (SteveInFrance ?) even calculated the volume difference and posted it here years ago.

That's why Jaguar, in more than one doc., goes to the trouble to specify that you fill to the upper mark only with the top down, to a lower point with the top up. Other manufacturers do the same.

This wouldn't matter much if it were not possible to overfill the system ... but it is possible. Fill it as Jaguar says to do.

 

Dennis is correct - the lift cylinders are double acting hydraulic rams - the difference in volume between up and down is due to the volume of the ram when retracted (i.e. when the roof is down) inside the cylinder.

 

Pump fluid level with roof open and roof closed on my 99 XK8

Edit: The amount of fluid (the change) is insignificant and has no value! If you notice my tank is overfilled by a small amount that brought the level of fluid higher in the tank causing the fluid change to appear greater than it really is because of the cylindrical shape of the tank when the roof is open. No need to be overly concerned as long as you fill only to the top line with the roof open or closed.

 

I found that the top would not release from the latch unless I put in fluid above the top line. Now it works great.

 

This may seem facile but where is the filler tank located on my 1998 XK-8? Thanks in advance.

 

And the assumption would be there's a leak if low?

 

The tank is in right rear of trunk above cd changer. You will need to remove spare tire cover then the fabric covering cd changer. It will be obvious after that.

 

Thanks man.

 

The roof on my 1996 XK8 stopped going down. The quarter windows go down but that's all. After reading the thread I checked the fluid tank. It looked at about the lower level but to be sure I added a few mls. Still the roof will not go down, although I can hear the pump.
I figured it must be an unlatching problem. I noticed a post from stevepaa who said he had the same problem and solved it by overfilling the tank. Does anybody have experience or an opinion on this?

 

Any chance the valve on the side of the pump was opened? That would cause this.

as I recall its handle is a 3 inch long thin metal rod. Normal threads ( righty tighty )

John

 

maringa I sent an email response to your questions sent me. Let me know if you didn't receive it today. and I can post it here.

 

Vern thanks for your suggestions. I figured it must be a latch not unlocking problem, so I got out the Allen key and used it to turn the latch manually a couple of times (for readers not familiar with this, the handbook describes how to raise the top manually if the pump fails and lock the latch manually). I then tried using the switch to lower the top and it worked. I sprayed some silicone lubricant on the latch mechanism.
John L

 

 

Check the fluid first.

Gus
www.jagrepair.com

 

Mine does the same (and my fluid is also full). "It's a feature".