Best way to patch up this urethane dually fender

Vanillagorilla

Vanillagorilla

Professional amatuer
Hi. Ive recently bought a 06 f550 dually to flip. When I first done the deal I asked on here what the fender was made of. I got a reply of urethane. Due to the yellow color I think thats correct. I was also told that it cant be welded..... I tried my normal car lot bumper repair procedures anyway (hot stapler and trying to melt in plastic filler rod in the crack. Didnt work.
Anyway i think I can probably glue the cracked area together with fusor 142 or something similar?
Also, theres a missing section. Before I realized how difficult this material was, i thought about fiberglassing in a section.
Now I dont think that it would adhere.
Does anyone have any insight on repairing this? Doesnt have to be perfect. Its a flip. Doesnt need to last forever, but dont want it falling apart for a while. So ghetto ideas are welcome. Thanks in advance.
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If you go to Polyvance's website you will find a video detailing pretty much what you are asking. It's pretty much the same procedure I learned some years ago. FWIW fiberglass will not hold very long. Not the way to go about it.

Video is linked on this page.

Polyurethane repair videos

Videos on how to repair broken polyurethane (PUR) using products from Polyvance
www.polyvance.com www.polyvance.com
 
If you don't have a welder like described you can try doing one of two things, easiest would be to source a piece of similar PU and fit it like a patch then use a PU compatible repair material like SEM problem plastic repair or similar 3M 5895 (I think that's the number) would work as well. Been a long time since I did one like that so read the TDS of the product you are considering to make sure it's compatible with TPUR. SEM PP is made for olefin type plastics but it sticks well to urethane as does the 3M 5895.

Get a suitable piece for a patch, tape it together on one side with aluminum tape or similar. Clean and roughen the surface on the other side. Remove any paint. Leave a gap between the patch and the existing material. After setup remove the tape and do the same to the other side. You can also bond a backing strip or strips to the backside when finished to strengthen things further.
 
Any piece of automotive TPU will work. You can heat you patch some to reshape or shape to better fit the missing section. Be sure to V those cracks well and remove any material exposed to the elements. You want the PU to be bright and clean.

You can find a patch fairly easily going to a collision shop and asking if you could look through their pile of removed bumper covers. Most Shops wouldn't care and many have a literal mountain of removed covers laying around. Or scrounge the salvage yard and find a damaged cover or dually fender and get your patch that way. If you can find a like dually fender that is damaged but good in that area, cut your patch so that you can replace that whole area and not have to mess with the cracking on yours. That would be my preference.
 
We welded urethane in college. Special filler rod and the base does not melt.

I have fixed a lot of urethane as crown vic OEM is urethane. 3m repair material and the mesh reinforcement tape. Never had a failure.

If you are trying to do a topside only repair, you need to grind off enough so you can bury the reinforcement mesh. I have done it when I had to. You can use mesh drywall tape if you don't have the proper stuff. Can use a little crazy glue to hold the tape in place.

That repair does not look too bad. I would mesh tape over the missing part and fill it. Use some 2 inch tape to hold the repair material from falling out and keep it's shape. We call those a hot patch up here. Can use plastic as well. Can put the repair material on the tape first and then stick it on.
 
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