Prius Trouble: Undercarriage

October 3rd, 2011 by Potato

The Prius has been a terrific car for me, giving me almost zero trouble since buying it (only needs oil changes twice a year, and only one rattly panel as a manufacturing defect).

That is, until this weekend. On the trip up to the cottage I heard a strange whooshing noise, kind of like a window being open a crack: a non-specific change in the way the airflow around the car sounded. Then it stopped. When we got to the cottage I found out what the source of the mystery noise was: the oil access door had broken and been grinding against the road.

For those that aren’t intimately familiar with Prius anatomy, the underside is covered in plastic panels that help improve the airflow under the car, which in turn improves fuel economy (and there is a debate as to whether it helps keep out or trap wintertime salt, which may improve/hurt the long-term life of the underbody in the Canadian climate). It also helps insulate road noise (making the car as awesomely quiet as it is) and also importantly in northern climates, helps to insulate the engine compartment (retain heat). But, as you can imagine, you can’t work on an engine that’s hidden by panels, so there’s a small access door to open for oil changes. This has a very rudimentary hinge in the plastic: just a creased spot in the plastic panel where it bends. It’s then held on by a few (3?) plastic fasteners. If you’re familiar with this type of plastic hinge (in cheap plastic storage boxes perhaps) then you’ll know they have a nasty habit of shearing, and the cheap plastic fasteners aren’t of much help if the hinge gives way. It’s a real falling-down point on the Prius design (the whole panel should be removable, not on a hinge, or the hinge should be stronger/more flexible).

When I looked under the car, that door was held on by just one of the plastic fasteners, and the plastic had been ground away by contact with the road so the door was now some 2-3″ shorter. It was a bit of an adventure to get that last fastener off so I could drive the car. Here’s our improvised cottage jack to get the car up high enough for me to reach under, and then a picture of the hanging access panel itself. It’ll have to be replaced, and since the door hinges on to the larger piece, likely the whole larger piece will have to be replaced. Ugh.

I can’t say for sure at this point if this is a defect under warranty or not, but I think it should be. I’ll keep you posted when I finally get my butt into a dealership to figure it out, but it does sound like it’s already a common problem (on a model that’s less than 3 years old) and likely only to become more commonplace. Some DIY fixes have been proposed over at PriusChat. I’ve found a TSB for the US that indicates this part has been redesigned. I can’t find any information on whether this applies to Canadian owners.

5 Responses to “Prius Trouble: Undercarriage”

  1. Netbug Says:

    Stupid question, but doesn’t your car come with a jack for replacing a flat that you could have used to lift it?

  2. Potato Says:

    It does, but we didn’t trust the jack on a rough gravely surface when I had to get my head and shoulder under the car. Since we only needed a few extra inches, this worked well :)

  3. jonathan Says:

    I though it was becuase wasting the hydrolic fluid in the jack would be on Prius like, a rock is more environmentally friendly, I’m sure the 2012 will just come with a rock in place of a jack…

  4. jonathan Says:

    “on prius like” should read “un-prius-like”

  5. wayfare Says:

    jonathan: ROTFLMAO

    Potato: I really think you need to post the picture with your head wedged under the car.