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Rob Edwards 10-07-2008 03:55 AM

Cooling flap shroud R&R/Plastic repair question
So I wanted to do a cooling flapectomy- my cooling flap motor is in the way and needed to come out. So I went looking at flapectomies that involved hacksaw blades, and tearing out the shroud that attaches to the flaps. After looking at the price of the cooling flap shroud ($250 for new....) and deciding that the ducting is convoluted enough in its design that Maybe It's There For A Reason (and messing around in a previous life with old Corvettes that rapidly overheat without hte correct shrouds) , I decided to see if I could do a destruction-free cooling flapectomy.

First, if you need to to take the nose off an S4, forget everything in the archives about it being a PITA, removing the headlights, lots of combinations of socket extensions, U-joints, etc. Yes, you need the car in the air, and you need to pull the wheels, forward wheel well panels and spoiler, and the headlights need to be in the up position. The trick is an 8mm reversible gearwrench. From putting the car in the air to pulling off the nose took just under an hour. There are sixteen 8mm nylok nuts and 5 screws holding the nose on (2 thick spacer washers on the middle three screws). Then unclip the side marker harness from the clip on the back of the turn signal housing, unplug the foglamp and turn signal harnesses, and the front bumper cover just pulls right off.

From intact to this in 60 minutes:

Front right blood n' guts:

Driver's side:

Passenger side: (don't forget to unclip the side marker harness from the clip....)

The designers were nice enough to put a worm-drive clamp (and not an Oetiker clamp) on the supply hose to the headlight washers:

With the nose off, the target is in view:

I then removed the shroud and flaps. Tony's description of his flapectomy ( are spot-on, it's just not obvious how to get to the the 4mm hex head bolts with the shroud in place. Here it is for dummies:

Looks like the front bumper shocks are original......

So- with the 4 screws across the top removed, and the 4 hex bolts out, the shroud and flaps come out:

The shroud comes off with 4 screws and then spreading three small clamps with a flat screwdriver.

To gut the cooling flaps, the center hinge cover comes off with a 7/32nds wrench:

Then the pair of flap shaft 'bearing caps' (for lack of a better term) can be gently pried out from their ends. Here's the center cover and part of a bearing cap at the bottom:

Then the motor and the actuator shaft come out- 3 10 mm bolts and a 6(?) mm nut on the end of the actuator arm:

Then the center hinge needs to be disassembled. The hinge is a U-shaped plastic piece with three hollow plastic 'axles'. The center axle is connected to the motor, and the outer two have metal pins in them. Drive the pins out with an awl:

Then the hinge can be pried open with your fingers:

This releases the levers of the cooling flaps, which can then come out of the frame :

Then the shorud can go back on the frame and back onto the car, preserving airflow to the radiator, and making more room in front of the A/C condenser.

Now- my questions: The shroud is cracked along the top where it screws to the cooling flap frame (I have all the missing fragments):

How best to repair this? Does anyone know what kind of plastic these are made of? There are several posts about plastic welding and epoxy repairs and links to, but I don't know what the best way to repair this. The gut instinct is just to tape across the cracks and slather epoxy on it, but I'm all ears for better solutions.

Here's the ID on the shroud, also embossed with 'KK' and that icon. Any plastics guys know what it means? My guess based on the flow chart at USC is that it's polypropylene?

This is obviously a lot of hassle for what it accomplishes, one could probably fish the motor out without even removing the flaps (?). I just hate to break parts if it's not necessary. Besides, I was replacing the front spoiler anyway, so WIWAT......

jon928se 10-07-2008 04:41 AM


I suspect that bizarrely there is a mix of plastics in the shroud. I had some repairs to do on the SE, bits of shroud would come undone from there normally position and oscillate in front of the cooling flaps causing some scary "rattling" noises - road speed and wind direction dependant.

My most succesful repairs to the plastic parts have been using pieces cut from cheap kitchen cutting boards (HDPE) melted into place with a combination of soldering iron, hot glue gun and hot air gun. The bottom part of the shroud I remade using 0.75mm thick alu sheet sprayed matt black.

I also succesfully refixed the boss (that the intank pump or strainer screws into) on the gas tank using HDPE cutting board melted into place, and the fender liners.

Bill Ball 10-07-2008 01:40 PM

Did you find that metal bracket, one on each side of the car, was attached to nothing at the bottom? Same on my car.

Rob Edwards 10-07-2008 01:52 PM


I'm pretty sure it's supposed to be a mounting point for one of the 3 or 4 vertically oriented screws (per side) that attach the spoiler. I recall looking in there pre-disassembly and thinking that I'd need to undo the bracket from the frame rail to get the spoiler off, but that's clearly not the case. I can't remember whether I took a picture of the area before I pulled the spoiler, I'll check tonight.

RyanPerrella 10-07-2008 01:54 PM

yes the front bumper is actually quite easy to remove.

Rob, Does this mean your old spoiler will be available soon? :thumbup:

RyanPerrella 10-07-2008 01:59 PM

Originally Posted by Bill Ball (Post 5878890)
Did you find that metal bracket, one on each side of the car, was attached to nothing at the bottom? Same on my car.


That does in fact attach to the spoiler, there is one on each side and it probably looked as if it went to nothing because you pulled the screw before you pulled the bumper cover off. But it does attach via the spoiler to bumper hardware.

Rob Edwards 10-07-2008 02:00 PM


Part of the motivation for doing this was getting the old spoiler off in time to bring it to SF08. :thumbup:

RyanPerrella 10-07-2008 10:46 PM

Originally Posted by Rob Edwards (Post 5878950)

Part of the motivation for doing this was getting the old spoiler off in time to bring it to SF08. :thumbup:

awesome :biggulp:

Rob Edwards 10-15-2008 04:28 PM


I ended up epoxying the cracked shroud with a plastic-specific epoxy, and re-assembled:

Getting the bumper cover on without folding over or bending down the the lips of the shroud is a litle tricky, you need to make sure that the forward edges of the shroud all tuck into the channels that surround the opening in the bumper cover.

In situ:

dr bob 10-15-2008 06:07 PM


That bolt that's in the front to hide/protect the hole for the tow eye-- Ever had that out? Mine has a hex bit broken off in it. :( I've been a little timid about using power tools there so close to the bumper plastic, like a diamond burr in the die grinder maybe. Looks like pulling the bumper shell might be a good option.

Rob Edwards 10-15-2008 06:27 PM


Funny you should mention it, I hit it with Kroil while pulling the nose, and managed to get it out with a big T-handled 6 mm hex wrench. I REALLY had to lean on it to break it loose, I was afraid I'd stripped the plug. There was a LOT of dust/dirt stuck in the threads, and some corrosion. I blew it all out, cleaned up the threads, put some anti-seize on the plug and gently put it back in. I bought one of the GTS rubber plugs and may put it in there instead. Definitely gets you more clearance to honk on the wrench (or drill it out) with the nose off. There's also a TON of cleaning that goes a lot easier with the nose and spoiler off.......

CardinalCar 08-18-2014 10:04 PM

Originally Posted by Rob Edwards (Post 5903894)

I ended up epoxying the cracked shroud with a plastic-specific epoxy, and re-assembled:\

Hi Rob --

You'll be glad to know your repair lasted approx. 6 years. But the 928.575.521.01 front section has basically disintegrated and needs to be replaced. The back section is still fine.

Mark doesn't have any used ones, there aren't any on eBay, and none of the US distribution centers have any. Roger can get them air-dropped from Germany so that's what I'll probably do, just waiting to confirm if I need to order anything else at the same time.

The body guy also discovered various minor hardware in the passenger door had cracked due to age, or was on the verge of failure, so he's dutifully fixed it all. Driver's side next week. He has to take the doors apart to weld the holes from the side mouldings (they look PERFECT when he's done) so it's very much a case of WYIT...

Michael Benno 12-30-2016 09:52 PM

Rob, thanks for the handy tutorial, I was able to remove the flaps from the duct and reinstall on the car. It was pretty easy for me since I already have the bumper off for repair and repaint. Thanks to @FLYVMO for your help as well.

Mike Benno

Mrmerlin 12-31-2016 09:45 AM

To answer a question from Bill,
the long metal brackets attach to the lower edge of the bumper cover,
the spoiler then attaches to another hole adjacent to the bracket.
The spoiler is not attached to the bracket as its meant to float so hitting objects will not deform the fixed mount

Adk46 12-31-2016 02:14 PM

This is timely, since I'm replacing a busted-by-fallen-tree duct and vane assembly as soon as Roger gets one from the motherland. I've already gotten the other parts I'll need (splash shields, spoiler, etc.), and the bumper cover is at my body shop for minor repairs and new paint. I was pleasantly surprised that new parts are available.

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