Repairing cracked plasitc cowling and wheel well rust

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A friend of mine got side-swiped when someone changed lanes into his lane and pushed him into the guard rail. I previously posted on removing tire marks (Best Rubbing Compound for black tire marks) and removed them and the paint from the other guy’s car. Thanks.

What is the best way to repair the cracked plastic cowling (not sure if that is the right word) and fix the rust in the wheel well? Can I attach photos?

Thinking of holding the cracks together from the outside with tape and fiberglassing from the inside. I know how to fiberglass but will it stick to the plastic?

I have heard rust starts from the inside so sanding and filling from the outside isn’t going to work. Correct? I will remove the wheel well liner and am looking for tips on how to sand from the back-side of the wheel well where space and visibility are limited.


Fiberglass won’t work to repair the “cowling”… actually the bumper cover. I have successfully repaired cracks on my car with sheet aluminum pop riveted and epoxied to the backside. Countersink the rivet heads and use a special 2 part repair filler designed for flexible covers (not Bondo) to fill the crack and rivet contersinks. I did this on a racecar that didn’t have to look perfect. It didn’t. This is a kluge.

Rust does not start from the inside. Rust starts wherever there is bare steel or iron. Filling and sanding from the outside works and is the way many dents are repaired.

Yes, you can post pictures.

Yes. Transfer jpg file to computer, then click the upward pointing arrow in the forum’s post compose/edit window, at top, 7th from left.

I expect the fiberglass will stick ok, but wont’ solve the underlying rust problem, so eventually rust will get worse and fiberglass will fall off. Might buy you some time though. If the panel is designed to be a replaceable part, new panel is probably your best bet.

If the wheelwell rust you are discussing was already there before the accident… it could come from the inside or started from the outside. You need to determine this by inspection and grinding a little off. The rust must be removed for any repair method to stick. Lots of YouTube videos on this.

Why is insurance not involved or was this a hit and run ?


Thanks, As a new user I am limited to one image. Repairing the front bumper covering is where I need the most help so picked that one.

For the rubber bumper cover and the other rubber part. you can buy a bumper repair kit at an auto parts supply house. I will have the filler that will stick and be flexible. Sand and finish same as body filler. Yeah you may need to pop rivit some backing or use mesh reinforcement with the bumper filler material. Then you’ll have to paint. The stuff is not cheap anymore though but fiberglass will just flake off.

Thanks. any tips on what 2-part epoxy to get? There are a gazillion of them at Home Depot and Lowes. I bought some 2-part epoxy to repair an ABS kayak last year. Think that might work?

Since the 2-part epoxy will hold the sheet aluminum in place is it advisable to epoxy the aluminum, secure it in place with sheet metal screws, and remove them when the epoxy cures? Don’t know if the bumper cover is thick enough to recess the pop rivets. Any thoughts on using epoxy with fiberglass cloth?

Go to an auto parts store that sells body shop supplies, not Home Depot. Fiberglass won’t work on bumpers.

The waterproof epoxy is a good choice so if it worked on tne kayak… Yes fiberglass cloth, not mat, should work. Tape on the outside should work, but, make sure the joint is in the right shape when you epoxy it. Maybe cardboard along with the tape.

Before going to all that work, check price for a bumper cover, new, aftermarket, and auto recycler (junk yard).

I too am curious about not using insurance.

The car was totaled, insurance paid my friend the car’s value and he got to keep the car.
$50 for epoxy (I have fiberglass cloth), three hours of work (ie FUN), and custom-made color-matched aerosol spray paint should do it.
A new, used, or aftermarket bumper cover will cost much more and I wouldn’t learn how to repair a broken plastic bumper cover.

Thanks for asking.

Ah, now that makes sense, thank you.
Of course another fun option, enter it in a destruction derby.