Q The tilting glass sunroof in my car has been getting fussy lately. Sometimes it initially won’t close, but finally does after a few tries, and it’s making some bizarre popping and scraping sounds. As you’d imagine, this is no fun in winter. Can I fix this myself?
A You’d think sunroofs would be just as reliable as power windows, but turning a sliding panel on its side makes the mechanics far more difficult. A sunroof doesn’t just slide back and forth; its mechanism must also tilt the panel up and down to accommodate the sliding and venting motions. So, in addition to the electric motors and switches and slides in windows, sunroofs have plenty of additional parts – which are typically the ones that break.
Popping and scraping noises are generally not happy sounds for cars to make; in a sunroof they indicate surfaces binding, drive gears slipping, or, put plainly, that something mechanical isn’t working correctly. It’ll probably break for good when it’s least convenient (and raining).
There are two approaches to repairing an ailing sunroof: the first is to fix what you’ve got, the second is to replace the whole megillah. All the greasy bits of sunroofs live between the roof sheet metal and the headliner. Before you start pulling the car apart, find a place to work inside or check the weather forecast – being caught with a hole in the roof during a downpour wouldn’t be fun. The first thing to try is removing the glass panel. If you can, tilt the sunroof panel to the “vent” position, which should give access to the screws holding the panel. Remove them, and with the sunroof glass off, you should gain access to the moving parts for an easy inspection.
Look for cracked or stripped gears, a buildup of dirt and debris, or anything else that looks like a problem. With the glass panel still off, turn on the car and cycle the roof control through the open, close, and vent positions to identify problems.
In your case, it sounds like you might be able to get away with replacing the gear on the motor at the front of the sunroof, but without opening it up, it’s impossible to know.
If you do find and fix the problem, clean everything, then slather it with lithium or marine grease for smooth future operation. If you find nothing, don’t bother putting the sunroof back together because you’re just going to end up removing it all anyway.
Installing a new sunroof is a big job – you’ll have to take off the interior trim around the door pillars as well as any overhead handles or dome lights, then pull the headliner down, disconnect the sunroof wiring harness, and unbolt the whole mechanism. It’s in one big rectangular piece called a cassette, which should swap for the new piece without any fight. Be sure to do a function test before putting the interior back together; it may need a little jiggle for a perfect alignment.
To answer your final question, yes, you can do this repair, but it’s complicated enough that it may be worth the cost to have a mechanic do it.