Prius Undercarriage Follow-Up

October 17th, 2011 by Potato

I had the under-engine cover replaced today. It went well: though the US TSB I found didn’t apply in Canada, they did have the newly revised part in stock anyway, and replaced the cover under warranty.

The new part still doesn’t have a proper hinge, but the bit of brittle plastic that bends is a little more sensibly designed:

The new under-engine cover, focused on the hinge, which now has a bit of a roll to it.

Since we were taking the cover off anyway, I decided to do my next oil change, etc, a little sooner than necessary. The weather is just barely below 15°C these days, but I do much of my driving at night, so I also had them put the winter tires on. A somewhat unexpectedly expensive step was getting the transaxle oil changed. Oddly enough, there is no recommended change interval: just an “inspect and replace as necessary” guideline in the maintenance schedule. Except there’s really no way to do that: there’s no dipstick, so you have to open the drain plug anyway, and no real way to cheaply test the viscosity or for contaminants. Some of the car geeks have been doing that analysis to try to come up with our own user-generated set of change interval guidelines, and the initial evidence is that the first change should be made pretty early on (about 2 years in, so pretty much where my Prius is now). I didn’t bother to try to save any of my transaxle oil for analysis, but it was discoloured relative to new oil. I’ll probably plan for the next change at about 120,000 km, though I’ll be watching the high-mileage geeks for hints ;)

The service guys were pretty good, and let me poke around under the car while they had it up on the jack. Unfortunately, it looks like there’s a little bit of rust starting in places (a few bolts, and on a spot by the exhaust system, pictured below). For a car in Canada, a few little spots of rust is nothing, but it has only gone through one and a half winters, so that’s a little more than I wanted to see this soon. This particular part of the exhaust, around the heat exchanger (unique to the Gen 3 Prius AFAIK) is a bit of a hotspot for rust, and he hypothesizes that there’s a chance that may be a recall item in a few more years.

I’m going to look into perhaps rustproofing: I used Krown oil spray on the old Accord, and I think it did the job, but I’ve been hesitant with the Prius since it is a bit different. The tech at the dealership said it wouldn’t help there, since the exhaust system will get hot and burn off an oil spray — it’ll just stink it up for a while is all. I don’t recall that happening with the Accord though. Instead, he recommended a tar-like coating, which I’ve always been a little leery of vs. the oil spray technique. Anyway, something to think about.

Some rust starting to appear on the exhaust system on a 2-year-old car.

Though I didn’t like the look of the rust on the bits that had it, I was a little amazed at how clean most of the underside of the car was. Granted, my last car was 14 years old when I finally got rid of it, and though it wasn’t structurally unsound, there was not a single part underneath that didn’t have at least some rust veneer.

One other potential issue they pointed out was that a small ridge was developing on one of the brake rotors. I don’t know how serious that really is — as long as the pad conforms, and it’s radially symmetric, it should still function as a brake, right? — but he told me to watch for any signs of shaking while braking, etc. The brakes themselves still have a tonne of life left on them: that’s as expected since much of the braking is regenerative, not friction, but still nice to have confirmed.

One Response to “Prius Undercarriage Follow-Up”

  1. Netbug Says:

    You should see the underside of my car; we had it on the hoist last weekend and literally tapped a 4″ diameter hole in it. The rust is ridiculous.