Go Back   EcoModder Forum > EcoModding > Off-Topic Tech
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-05-2015, 02:34 PM   #1 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,218

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
Thanks: 2,981
Thanked 5,852 Times in 3,033 Posts
2004 Toyota Prius body rust / corrosion (rocker panels, front fenders)

NOTE: I split this discussion from my Prius build/ecomodding thread because it's something specific that other owners will be searching for more and more as these cars age.

---

My 2004 Prius is rusting out in several places.

It's worst in the rocker panels, but the front fenders have also started to go. This thread will show where and hopefully why the corrosion has started,so owners of newer cars (or older cars in less rust-prone parts of the world) can take steps to prevent it.

Eastern Ontario & west Quebec are perfect laboratories for discovering automotive design flaws that cause rust by trapping moisture, winter road salt (the killer) and dirt.

Here's what the rocker panels look like when I got the car





It was easy to poke that screwdriver through the side of the car.

I have an idea about the cause/path of this rust, and hope to offer some good preventive info to owners of newer cars (or cars that live in less salty winter environments) that haven't begun to rust... yet.

Attached Thumbnails
Click image for larger version

Name:	$prius-rocker-rust.jpg
Views:	18
Size:	57.2 KB
ID:	18414  
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following User Says Thank You to MetroMPG For This Useful Post:
Speeed3 (08-08-2015)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-07-2015, 06:19 PM   #2 (permalink)
EcoModding Lurker
 
Join Date: Jan 2011
Location: Finland
Posts: 13
Thanks: 6
Thanked 2 Times in 2 Posts
How do you think the rust started?
It looks like it started from inside. Rusted trough wheel well got dirt in there? Some clip from bottom plastic paneling fell off and allowed dirt in there? Just by itself? Some other way?

Maybe you (mostly meaning other Prius owners) can put rust preventing oil into there from rear spat attachment hole.

Last edited by Speeed3; 08-07-2015 at 07:11 PM..
  Reply With Quote
Old 08-07-2015, 11:36 PM   #3 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,436

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
90 day: 54.34 mpg (US)
Thanks: 142
Thanked 1,209 Times in 639 Posts
On the 3rd gen, that whole area is covered by a plastic rocker panel.



I wonder if this was one reason Toyota made that change. Is rust in that area common?
__________________

  Reply With Quote
Old 08-08-2015, 12:22 PM   #4 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,218

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
Thanks: 2,981
Thanked 5,852 Times in 3,033 Posts
Quote:
Originally Posted by Speeed3 View Post
How do you think the rust started?
It looks like it started from inside. Rusted trough wheel well got dirt in there?
It's definitely rusting from the inside out. The rust is a lot more widespread than the photo shows because once the paint has blistered, the metal beneath it is all corroded.

I haven't opened up the rocker panel yet to confirm, but I believe the problem has to do with this "shelf" at the bottom of the rear wheel arch (ahead of the rear tire) that holds dirt, salt & moisture:



You can't see it well in the pic, but where the yellow arrow points, the tip of the screwdriver that I stabbed into the car is visible at a small hole there. Which means water, salt & dirt are getting in the rocker cavity there.

Also, all the factory undercoating has flaked off that shelf, exposing bare metal.

Quote:
Maybe you (mostly meaning other Prius owners) can put rust preventing oil into there from rear spat attachment hole.
Exactly! I would highly recommend drilling the rocker panel where the rear doors close (above the door seal) to spray something for rust prevention inside the cavity.

And when I cut the existing rust out of the rocker panel to repair it later this summer or early fall, I should be able to confirm the source.
Attached Thumbnails
Click image for larger version

Name:	$prius-rust-sourc-arrow.jpg
Views:	1717
Size:	75.7 KB
ID:	18415  
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following User Says Thank You to MetroMPG For This Useful Post:
Speeed3 (08-08-2015)
Old 08-08-2015, 12:25 PM   #5 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,218

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
Thanks: 2,981
Thanked 5,852 Times in 3,033 Posts
Quote:
Originally Posted by Vman455 View Post
On the 3rd gen, that whole area is covered by a plastic rocker panel.
The problem with those plastic panels is if there's still a design flaw in the car, you won't know that the car is rusting out behind the plastic until it falls off! I've seen lots of cars with plastic rockers that hide serious corrosion.

Quote:
Is rust in that area common?
Yup. Now that I have the Prius, I'm paying attention to them, and have seen the rust bubbles on the rockers of several earlier 2nd gen cars around here.
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 08-08-2015, 12:29 PM   #6 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,218

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
Thanks: 2,981
Thanked 5,852 Times in 3,033 Posts
front fender rust too

I'll post a pic later, but there's also rust starting in the front fenders as well, behind the tire.

It's in the location of the holes in the wheel arch where the plastic inner fender liner & mud guards attach to the panel. On the passenger side of my car, the corrosion has crept around the corner from the tabs out onto the side of the fender.

UPDATE: some pics...







Attached Thumbnails
Click image for larger version

Name:	$priusfender-rustmudfl-on.jpg
Views:	1682
Size:	47.3 KB
ID:	18416   Click image for larger version

Name:	$priusfenderr-rust-mudflap-.jpg
Views:	1720
Size:	47.7 KB
ID:	18417   Click image for larger version

Name:	$priusfenderr-rust-tab.jpg
Views:	1700
Size:	39.6 KB
ID:	18418   Click image for larger version

Name:	$priusfenderr-rust-inside.jpg
Views:	1699
Size:	45.8 KB
ID:	18419  
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
The Following User Says Thank You to MetroMPG For This Useful Post:
Speeed3 (08-08-2015)
Old 08-08-2015, 01:02 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Jan 2011
Location: Finland
Posts: 13
Thanks: 6
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by MetroMPG View Post
Exactly! I would highly recommend drilling the rocker panel where the rear doors close (above the door seal) to spray something for rust prevention inside the cavity.

And when I cut the existing rust out of the rocker panel to repair it later this summer or early fall, I should be able to confirm the source.
Maybe you don’t need to drill a hole. (From parts diagram) It looks like rear tire spat is attached to plastic plug with one screw. So maybe you can remove the tire spat and then pull the plastic peace of and then use its hole to put oil in there. Or maybe you could use the attachment holes for rear door sill panel.

Prius rocker panels have inner structure. Only pictures that I have found:
http://techno-fandom.org/~hobbit/pix/hf07/156aby-ch.jpg
http://priuschat.com/data/attachment...5_23.31.29.jpg

Looking forward for your pictures.

EDIT: On the other hand is it even that beneficial to protect the inside of the rocker? If that hole was rusted and worn into the wheel well wouldn’t just stopping the hole from appearing stop the rust from appearing? Or is the hole in there from the factory? Or did that hole start from inside?

Last edited by Speeed3; 08-08-2015 at 01:20 PM..
  Reply With Quote
The Following User Says Thank You to Speeed3 For This Useful Post:
MetroMPG (08-08-2015)
Old 08-08-2015, 02:02 PM   #8 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,218

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)
Thanks: 2,981
Thanked 5,852 Times in 3,033 Posts
Thanks for those picture links of the rocker structure! We'll have more when I cut out my rust.

I suspect the hole on the "shelf" in the wheel well was caused by rust, and then salty water & dirt got inside from there. So if you could prevent the hole, you prevent the rocker rust.

I would still rust-proof the inside of the rocker. It's normal procedure (commercial aftermarket) here to drill access holes to spray rust inhibitor inside hard to access areas. Then you put greased plastic plugs in the holes.

I'm posting pics of the front fender rust in a minute. I'll add them to the previous post, above.
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 08-08-2015, 03:10 PM   #9 (permalink)
EcoModding Lurker
 
Join Date: Jan 2011
Location: Finland
Posts: 13
Thanks: 6
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by MetroMPG View Post
I'll post a pic later, but there's also rust starting in the front fenders as well, behind the tire.

It's in the location of the holes in the wheel arch where the plastic inner fender liner & mud guards attach to the panel. On the passenger side of my car, the corrosion has crept around the corner from the tabs out onto the side of the fender.

UPDATE: some pics...
Front fender rust might actually be caused by attaching the front mud guard. Those J-nuts will wear (or even rip while attaching) paint off.

We use lots off road salt here. But for some reason Priuses don’t have front mud guards (which off coarse causes the paint to wear from rocker and then it rusts from outside). But since front inner fender liner attaches with plastic clips there’s no rust in there.

Last edited by Speeed3; 08-08-2015 at 03:23 PM..
  Reply With Quote
Old 08-08-2015, 03:12 PM   #10 (permalink)
Has two Insights
 
Gasoline Fumes's Avatar
 
Join Date: Oct 2009
Location: New York State
Posts: 1,225

CRXFi - '88 Honda CRX XFi

Insight 256 - '00 Honda Insight
Team Honda
Gen-1 Insights

Insight 5342 - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 71.83 mpg (US)
Thanks: 656
Thanked 543 Times in 316 Posts
Quote:
Originally Posted by MetroMPG View Post
The problem with those plastic panels is if there's still a design flaw in the car, you won't know that the car is rusting out behind the plastic until it falls off! I've seen lots of cars with plastic rockers that hide serious corrosion.
My outer rockers are totally gone. I can see the ground behind the plastic panels.

__________________
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com