Cowbells (May 1997)

Is there any relatively easy way to fix the cowbells in the back? The constant clanging and banging is driving me nuts, and having to drive with the window open when I have passengers in the car bugs me as well, expecially when it's cold).

I know it's because of the foam backing rotting away. Is there any special foam/glue I need to use? And how do I get at those vents to do the work?

I took care of my "cowbells" in my 1985 XJ6 a couple of weeks ago. The job is relatively easy, although it takes a little time and patience. Remove the carpeted panel at the front of the trunk (boot). This is held in place with plastic Dzus fasteners and covers the ECU, sunroof motor, and O2 sensor reset switch. Next, remove the fiberboard panel above the front of the trunk. You will have to bend this gently to remove it from the slot under the front of the trunk opening, but it comes out relatively easily. With the panel removed and lying on your back, you will see the large black plenum of the cabin air extraction system. This is held in place with six 9/16 (I think) nuts, and two 1/2 nuts near the trunk opening. The plenum will have to be gently pried loose, because non-hardening sealant has been smeared over its rear corners and it tends to stick in place. If you have a sunroof, you will find that you can't clear the two forward 9/16 bolts to remove the plenum.

If that's the case, you will have to remove the rear seat cushions. The bottom cushion comes out first, after removing two Phillips head screws under the front. Then you can removed the back after taking out two bolts and lifting the cushion up and out. Four nuts hold the sunroof motor in place. Removing them will allow you to move the motor toward the back of the car just enough to allow the plenum to clear the two bolts.

With the plenum out of the car, you will see that the foam backing on the four flaps has disintegrated. Drill out the eight rivets holding the flaps to the plenum, clean off as much of the foam residue and old glue as you can, and glue on new fabric. I used plain gray felt that I got from a fabric store for about 30 cents and glued the pieces in place with contact cement. On the bottom of the opposite side of each flap is a foam rubber strip that prevents the flap from banging against the side of the trough the flaps fit into. I removed each of these and reglued them lower down on the flap so that there was no chance of metal-on-metal contact.

You will need a pop rivet setup to replace the flaps in the plenum, but it might also be possible to use small bolts, nuts, and lock washers. But a pop-rivet kit isn't very expensive, and you will find other uses for it around the house.

Reinstallation is fairly straightforward and aided by the sticky sealant that holds the plenum in place while you fix the nuts. Reinstallation of the seat cushions requires a little pushing and shoving but isn't terribly hard.

I hope this is of help to you and others on the list. "Cowbells" is a common problem that'e easy to fix and brings considerable satisfaction when you shut the car's doors and hear--nothing.

There are six "cowbell" (air extractor) flaps. There are two attached to the vertical panel (seat back strainer) forwardmost in the boot. There are four more hidden above the black metal plenum, under the rear parcel shelf. The black plenum is easily loosened by undoing the threaded fasteners.

Also, put weatherstrip on _both_ sides of the flap? One side only is not sufficient, as the metal flap hits metal on both sides.

There is a right way and a quick way.

The right way requires taking the cover out from underneath and removing the flaps, replacing the felt and rubber bumpers and reassembling it all.

The quick way involves a tube of silicone (clear preferably) and about 5 min. Cut the tip off the long nozzle of a tube of silicone and snake it in the vents that are just forward of the trunk lid in the vertical edge piece. Inside there are 5 (i think) small metal flaps that are suspended from the top edge by felt. Carefully, using a screwdriver to assist, apply dabs silicone to the edges of each of these flaps to glue them to the backing panel and prevent movement. If you leave a small gap to allow air to escape, it would be helpful.

These flaps, combined with 2 others behind the rear seat, allow cabin pressure to vent when the doors are closed and the AC/heat is using outside air. I glued mine more or less shut a year ago and have noticed no problems. I suppose on a ten year old car that there are enough other air leaks to compensate.

Maybe someday fixing them correctly is in order, when I have a day to kill.