Sunroof Issues

Regarding an inoperative sun roof:

Verbatim, from the Series III owners manual: Where a sunroof motor has failed and the panel is stuck patially open, manual operation can be carried out by attaching a small handle, supplied with the tool kit, to a shaft protruding from the base of the sunroof motor. To gain access to the motor, remove boot front trim panel by releasing 2 quarter turn fasteners (Details are given in the Drivers Handbook).... ...If the sliding panel cannot be moved because the motor has seized, then the following emergency action can be taken. Remove the rear seat cushion and squab.... Remove the two nuts securing the wheelbox cover, and remove the cover. Remove the rack tubes from the wheelbox. Grasp the sliding roof panel and move it in the desired direction.

Hope this helps. The hardest part may be finding the tool, if the kit wasn't with the car when you bought it.

1. Check the output of the switch in the resting (open circuit) and both 'open sunroof' and 'close sunroof' positions - the 'open SR' and 'close SR'should see 12 volts. (You'll need a multimeter or at least a cheap testing light)
2. If the switch is putting out 12 volts to operate the sunroof and it doesn't move, I'd say you'd have a real problem (oh shit).
3. On the other hand, if you aren't getting 12v to the switch, find out why - The wires to the motor from the switch are one red and one green. The power supply to the switch is colored red/slate. The window lift relay is also used to provide motive force to the motor (and the window lift motors), so if the windows are working, you could assume this relay is functioning for the sunroof. However there is a thermal circuit breaker for the sunroof separate from the window lifts. If this is hosed, this could be the problem. I have no idea where this is (sorry) located in the car.
4. The sunroof motor itself is located between the reat seats and the trunk, and there is in this space a handle for manual operation of the sunroof. If you can get to it, try to operate the sunroof manually to be sure something isn't jamming it (lack of lubrication, leaves, whatever). If it works with ease, you can pull the electrical connection off the motor to see if its getting 12v - if it is and isn't working - time for a new SR motor.

I hope this helps and isn't too confusing

In addition to Jonathan's excellent advice, I submit the following to the list because I discovered something that isn't in the shop manual that fixed mine.

Disassemble motor from mounting bracket. Try hooking up motor to a battery charger (with an on-off switch) to see if motor runs. Test its running in both directions by reversing the connections from the battery charger.

If you feel the motor torque-jump or hear it try to run, but nothing moves; or if (as with mine) it runs in one direction and jams in the other, take the cover off the drive gear housing and take a look at the gearing inside. Chances are, it'll be covered with petrified grease. When you're finished, you'll want to clean all this out with carburetor cleaner and repack with a lightweight grease. What you're looking for right now are knackered gears. Coming out of the motor is the worm gear that drives the sector gear that turns the cable drive for the sunroof.

This is what was wrong with mine, and I was d*mn*d proud to have figured it out: look at the worm gear coming out of the motor. On the outside of the gearbox housing at the top of the worm gear is a threaded screw and locknut that controls the backlash of the worm gear. On mine, the locknut and screw had backed out over time, and when you ran the motor in the "close" direction, the worm gear would move too far and jam in the sector gear. If this is the problem, tighten down the threaded screw and tighten the locknut. You don't want this dead tight, as the worm gear has to be able to move a little to engage both sides of the sector gear teeth; one side when running in the "open" mode, and one side when running in the "close" mode. Check the motor running in both directions using the battery charger or in-car wiring as above. At this point, if the motor doesn't run, you're off to the junkyard for a replacement.

Max Harris writes:

I am having major disasters with my sunroof. The fact is it won't open or close. When I depress the switch the motor whirs but thats it folks nothing else happens.

I live in Ballarat Victoria Australia and if you have ever visited well you will realize you don't need a sunroof here... However the roof has an annoying little gap that (a) lets in water (b) whistles when you drive along it makes the car appear extremely noisy. And as everyone knows JAGUARS are the quietest thing to appear on the highway.

Please someone out there HELP. I have tried the manual winder and that doesn't work. And heaven forbid I even aplied a little manual pressure to the roof itself this closed it a bit but after my last trip ... you guessed it, the gap was there again.

Max, I just repaired an 86 XJ6 with the same problem. It seems the drive mechanism had lost one of its case screws spilling the drive gear innards. The drive is actually very simple and was easy to reassemble once I got to the thing. You'll have to remove the back seat, remove the cover plate from the over the cable assembly and then remove the drive motor from inside the trunk. It's pretty simple really.

Behind the rear seat back is where the motor shaft passes thru the wall and connects to the mechanism that opens and closes the sunroof.

Remove the rear seat bottom, (two bolts, at ankle level) remove from car. Then there are two more bolts that hold the seat backrest in place, where the seat and the backrest meet. Remove these also. Slide the seat backrest up vertically, to disengage the hooks at the top.

You will now see the sunroof mechanism. It has two cables, one on either side, going into what looks like a rectangular shaped piece of steel. This piece of steel has two small nuts.

Repeat.......Carefully remove them, and the steel piece will be able to be pulled off of its studs.

You want to do this slowly, as you will need to see how these cables, with worm gear ends are positioned. So that you can replace them correctly.

Once this is done, you will see the nylon gear. It will probably have a chipped tooth or two, or perhaps is broken altogether. It cannot be repaired.

You can order a replacement from Suncoast Conversions in the USA for approx. US$ 19.00. I had the same problem, last summer and tried to epoxy it, (it won't hold).

Just a bit of clarification on your wedgies - don't wear underwear and you won't be a victim!

Sorry couldn't resist. Anyhow if you look at each wedge opposite the slope side you'll see a small slot towards the bottom. This slot will engage a tab that is held next to each track by two nuts visible when the sunroof is fully open. The slope faces the rear of the car and with the adjusting screw in the wedge you can adjust the seal of the sunroof.

If you get a pop sound when opening the roof the ramps (wedges) need to be lowered or moved forward by backing off the two nuts holding each of the tabs. The pop means you're putting a strain on the cable at the nylon gear which will in turn begin to lose teeth. Between sliding the tabs and adjusting the height on the wedges a lot of adjustment is available to get the panel to operate just right.

I replaced mine, bought the replacement from either Special Interest Car Parts or HD Rogers & Sons - I don't recall which. Was the original Jag part. The Jag shop manual gives detailed instructions for R&R of the sunroof, but it comes out through the top. (From memory):

1. Open the sunroof about 9 inches. Then remove the three screws on the front edge of the roof.
2. Close the roof to within about 1 inch of closed, then lift the leading edge of the panel while gently pulling forward. It should slide right out.

To replace, there are tabs that engage a couple of spring clips on the back of the permanent portion of the sunroof.

OK, here's the physics. The effect is called Helmholz resonance, and is familiar to anyone who has blown over the neck of a beer bottle; you hear a note that is much, much lower than you would expect. If the beer bottle was an organ pipe, it would resonate at a quarter wavelength, or around about A above middle C; much, much higher than you actually hear.

In Helmholtz resonance, you need a geometry with a smallish opening, and a large body of trapped air. The mass of the air in the opening bounces on the compliance of the trapped air like a weight on a spring. In a beer bottle, the relevant mass is the air in the neck, and the trapped air is that inside the big bit of the bottle uner the neck.

Now you don't need a neck on a Helmholtz resonator; just a hole will do. An ill-defined region of the air in close proximity to the hole acts as the mass.

The frequency is set by the mass and the volume of trapped air. Lower mass, and bigger trapped volume gives a lower note.

Like all resonance effects, however, you can suppress, or damp the effect by increasing the losses. In the case of the Jag, that corresponds to an air leak through the open windows.

Furthermore, as you can verify with the beer bottle, you have to blow rather gently. Blow harder, and it stops resonating. Players of musical wind instruments are familiar with this effect; you have to put just the right amount of energy into the system, or very unpredictable things happen. I'm not sure of the precise dynamics of the process, but the beer bottle test confirms it. So it is not surprising that increasing the speed in the Jag stops the resonance.

I noticed a small bulge in the paintwork of my XJ6 - just below the Jag emblem behind the front wheel arch. I investigated by removing the panel at the rear of the wheel arch (four bolts and a Philips screw - the latter covered in underseal and hard to see). Inside is a cavity containing the fresh air duct, the lower door hinge bolts, and a drain tube. This drain deposits any water that may leak past the sunroof seal into a spot welded seam that subsequently corrodes and puts bulges in the paintwork just below the Jag emblem. It is now (belatedly) caulked.