Thanks, Dave, for that info. From the description in the Monkeys post, it sounded like this was such a complete mismatch between material and performance requirements that it must have affected other models, too. What's so silly is that plastics--I don't know about rubber--have been used in fuel line apps for some time now. That's what the Nylon 12 shortage was mostly about. I completely agree with you about materials selection. It still boggles me that with all the great stuff available it's possible to pick the wrong one.
I would agree with that, Ann. Ordinarily, Toyota has decent engineering and quality control. This flaw is a bit of a surprise. I think the point I was trying to make is that there is probably not a layer of higher quality engineering or quality control for the more expensive line.
@Ann: Judging by this press release, it looks like this issue affected Toyota RAV4's, Avalons, and Camrys, as well as Lexus ES350's and RS350's.
There were actually two steel oil lines, joined together with a short length of rubber hose, as shown in this picture. I'm guessing that the rubber union was used for ease of assembly. On one level, it's a smart design, because it's much more tolerant of dimensional variation in the assembly. The Achilles' heel in this design was the failure to select a rubber that could withstand hot engine oil.
Again, I'm just guessing here, but I suspect that the decision to go to an all-steel construction, rather than just replacing the rubber hose with one made from a better grade of rubber, was based partly on cost (one long steel oil line is almost certainly cheaper than two short steel oil lines plus a rubber union). Also, going to an all-steel construction meant that engines that have received the repair could be easily visually identified. I think a rubber hose could have worked in this application, provided that it was the right kind of rubber.
As a materials engineer, maybe I'm biased, but this seems like yet another lesson on the importance of appropriate materials selection.
Rob, unless I read this wrong, the problem with this Lexus was a completely wrong part installed (and presumably spec'd) for the function it has to perform: rubber hose instead of metal pipe. So doesn't that imply truly stupid design? And if that's happening on Lexus, then is it also happening with the *same* parts on Toyotas? Or did I miss your meaning?
Ann, in some areas such as engineering and probably quality control, the investment is likely the same. These disciplines are part of overhead and are not tied to individual products. I would guess that (as an example) Ford's engineering and QC on the Focus is the same as on the Lincoln.
At least on my cars the oil light has served as a very effective stall indicator, since the oil pressure drops rapidly when the engine stops rotating. And on several vehicls that had alots of miles, the light would come on at slow idle when the oil,viscosity was excessively low. But those were not expensive luxury cars by any stretch. Probably the oil light in a Lexus is intended to never illuminate, since that would indicate a flaw in the Jap engineering. And admitting to any problem would damage their egos.
I ran a chevy 350 CID low on oil at 150k. I thought I toasted the motor. Filled it up, checked the oil often (as it now smoked at start-up), and got 250k out of it before the rust won on the body! So this motor may survive, but will now need TLC the rest of its life.
I can testify that Ford and Mercury (before they were shutdown) had the same engineers, but different program managers and quality assurance people. For example, a simple plastic door panel was made from the exact same tool. The only design difference was the molded in part number and the ID badge. However, the Mercury parts had tighter tolerances than the Ford part. Thus, the tool and process was optimized to meet the Mercury requirements. Ford parts ended up being exactly the same. It would be interesting to know if the low end car using this chassis and engine combo was also a rubber hose?
Now as to the oil light, I have to agree with Lou. My 1968 has the 'oil' idiot light. That means when the oil pressure falls below a specified pressure, the light illuminates. Knowledgable people immediately shutdown the engine! The fact the Lexus was knocking meant the oil pressure was low and a light should of illuminated. It seems someone decided a level sensor is good enough, even though level sensors can become coated or stuck. The designer should of had an oil pressure switch as well as level indicator!
Turbineman, that's an interesting set of facts, and reinforces what Rob and were discussing. Even if the same engineers aren't designing both cars, the parts are engineered the same--in fact identically it seems. Which begs the question--what the heck *is* the difference that demands such a difference in price tag?
Rob, that's what I thought--that the engineers, or at least the engineering, wouldn't be different between mid-range and high-end cars. You'd think the QA would be even tighter. Once upon a time, more expensive meant higher quality.
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