97 XK8 convertible top hydraulic fluid flush and refill
 

Spring has arrived and I found the top opening and closing a bit sluggish. Checked the fluid canister in the back and it is half full (or empty). Since the hydraulic rams are double acting, am I right in saying it doesn't matter checking the fluid level with either the top up or down?

Would it be advisable to have all the fluid replaced or simply topping it up? I've owned her for 4 years and don't know what's been done by previous owner(s).

What is the proper procedure to completely drain the fluid? To what level should it be refilled? How much fluid would I need for a complete refill?

Lastly, what brand or specification hydraulic fluid is needed?

Thank you all so much in advance.

Is the fluid yellow or green? If it's green then the original fluid has already been flushed and replaced with the new type - Pentosin CHF 11S. There is a fill line on the reservoir. Be careful not to overfill!

Can't really tell what color is the fluid.

Never had the "green shower", so I'd have to siphon a bit off to determine the color.

Wonder if I can source Pentosin CHF 11S locally? Many thanks.

Sorry, I did not see your location when I posted! If your fluid reservoir is translucent like the one in my '97, then the green fluid should look very green. If it looks pale, that's probably the original (yellowish) fluid which was discontinued because it had a tendency to gum up and cause seals to fail. Here's a thread to peruse for some good information: https://www.jaguarforums.com/forum/x...-problem-5663/

I've finally had time to do my homework on this subject and TSB 501-33 provides all the information I needed. Turns out I'm way down on my fluid level ...

https://cimg7.ibsrv.net/gimg/www.jag...57f196eaf1.jpg

My first attempt to rectify the situation would be to top her up with Pentosin CHF11S Synthetic Hydraulic Fluid as directed by TSB 501-33, rather than a full fluid flush and replacement. The fluid should be easy to find locally as it is also used by BMW for power-steering. It comes in 1 litre cans, but my indy mechanic should be able to top mine up from his fluid stock. Cheers!!!

Yes, that's where my level was when I had a similar issue. The dealer topped it off and it's worked perfect ever since. Someone has already changed the original fluid out with the CHF11S, so you should be able to do the same.

About 15 years ago we flushed EVEYBODY's UNIVIS from the reservoir.

Remove (Suck or Siphon) the UNIVIS from the reservoir. Fill with Pentosin CHF-11S.
Operate the top to get the main rams filled with the Pentosin.

The best way to flush the long top latch lines is to remove the entire header rail with top latch assy.
Hang the rail and hydraulic lines out the left door and remove the lines from the latch.
Operate the pump motor with the rocker switch until the reservoir level drops low or until the fluid runs GREEN and has no air bubbles. Keep filling if necessary.

Reassemble.

Top up reservoir.

bob

Worth keeping an eye on the fluid level after you top it up - the Pentosin doesn't evaporate so if the level is down either the previous owner didn't top it up properly or there is a leak.

I've yet to positively identify whether I have Univis or Pentosin in her. I have a 97 convertible, and have not noticed any leakage at the latch or rams. Will let you guys know the outcome after Easter break...

She's got the green Pentosin. Topped her up with about 100ml and the top now works like a dream.

One place to check for leaks
 

I noticed a puddle of hydraulic fluid and a wet hose under my back seat years before the top started getting balky. I'm going to top it up this weekend but changing the leaky hose is on the chore list.