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Killing time this morning by Googling around, and stumbled on this article from last October published in Medium...

Why the Honda Insight is the Only Modern Folk Car

It’s a clear-eyed view of the car’s faults as well as what makes it special. I choked/chuckled a bit at the description of the car’s styling as an elephant suppository. Kudos to the author, Michael Banovsky, who I think lurks on IC.

I don’t remember seeing the article mentioned last fall, and a quick search didn’t turn it up, so thought I’d post it for your enjoyment. Apologies if this is a repeat.

Blessings,
 

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Not a bad article...

I've never see this seeming explanation for camshaft failure mentioned at IC, thought it was interesting and wondered if anyone around here could elaborate:

"One of the car’s engineered charms: its all-aluminum engine has the camshaft sit (stupidly) directly on the cylinder head, so when the timing screws up, the camshaft pounds its lobes into the surrounding soft metal as easily as an anteater burrowing for grubs."

The author erroneously refers to any Insight retrofitted with lithium as a "LInsight," when most of us know that that only refers to Mudder's project:

"With minor modifications, it can be grid charged, like a modern EV. Lithium-Ion batteries can be retrofitted, for a price (but mileage shoots up to ~150 mpg) and you can say you drive a ‘LInsight’."
 

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That doesn't make any sense to me.... Isn't it common for OHC engines to have the cam bearings machined into the cylinder head material?

"When" the timing screws up? Pounds its lobes into the surrounding soft metal?! I have no idea what he's talking about at all actually, lol. I thought the damage when running low on oil was that the chain gear snaps off. Seems like I've heard you can just replace the cam and keep going, but I can't remember. Maybe Scott can chime in.

Other than that though, it's a great article.
 

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"One of the car’s engineered charms: its all-aluminum engine has the camshaft sit (stupidly) directly on the cylinder head, so when the timing screws up, the camshaft pounds its lobes into the surrounding soft metal as easily as an anteater burrowing for grubs."
Yeah, this makes no sense at all. First of all it is the cam bearing journals which fail, not the lobes. Second, if I assume he is talking about detonation caused by too much ignition timing (?) then it seems to me that an open valve exerts no pressure on the cam, nor does a closed one. Normally, if a car suffers detonation, it breaks rings or pistons. I've seen plenty of detonation and preignition in high compression race cars and I've never seen cams damaged by it.

Otherwise, I liked the article. Occasional error or misinterpretation, but otherwise pretty interesting.
 

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I was under the impression that cam journal bearing failures where the result of oil starvation, either from low (or high) oil quantity or vtec filter clogs.
 

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I was under the impression that cam journal bearing failures where the result of oil starvation, either from low (or high) oil quantity or vtec filter clogs.
I don't think anyone has really figured it out. There have been several failures when the V-Tec screen was absolutely clean.

One theory is that coolant voids caused by inadequate purging allows a bearing journal to get overly hot. There hasn't been enough "quality" data on this theory to give it validity.

Almost certain that the oil starves; or at some point the oil film breaks down, and the journal galls and damages the bearing surface.

There have been other cars which ran this design (cam in simple aluminum bores) which did not experience the problem, so seems something particular to old and high mileage Insights - maybe after the first coolant change;)
 

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Interesting, didn't realize the bearings were getting chewed up. Would make sense though, something has to cause the cam to resist turning....
 

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Interesting, didn't realize the bearings were getting chewed up. Would make sense though, something has to cause the cam to resist turning....
Yes, the cam bore surfaces gall and then the cam "locks" up. There are no actual bearings in the cam bores in the head, just finely machined plane aluminum bores.
 

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Yep, often called plain bearings.


There's nothing wrong with them and they can give very long service life, but proper lubrication is critical. I like the idea of a babbitt lined Insight head. Scott should get on that. ;)

I collect antique small engines, most of which use plain, babbitt lined or bushing bearings... everywhere.
 

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So, it sounds like the author might have been suggesting that it's unusual to have the cam journals riding directly on bores machined into the aluminum head, maybe most engines have some kind of journal bearings? And then 'when the timing screws up' maybe the journals 'pound' into the aluminum?? Not suggesting it's right, I wouldn't know either way. Just suggesting that my paraphrase might be closer to the intent...
 

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All of the BMWs from the 1968 1600, thru the 1970-76 model 2002, thru the 320i and mid 1980s 318i and 325i, a span of almost 20 years, had the same arrangement, plain aluminum bore with no added bearing. (Probably all the big 6's also.) Even later BMWs may have the same arrangement - I just don't know first hand. Cam failures were not an issue. If it was good enough for BMW, then the arrangement should be good enough for a low power engine like an Insight. In all likelihood there are other cars running with the arrangement, just not sure what they are.

The problem is not lack of a babbitt bearing surface, though that could be a repair as Eli suggests, if appropriate size press bearings could be found. The cost of line boring the cam journals, buying and pressing bearing would likely be prohibitive in the eyes of cheap Insight owners, especially when serviceable engines can be found for $500.

The problem is not the bearing surface, the problem is elsewhere - as yet to be determined. In this regard, the author is blowing smoke;)
 

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Have there been failures where oil level is OK?
 

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iirc, some of the owners remarked that their oil level was ok. The discussion was rather furious about a year ago. Much of the speculation was focused on the V-Tec screens, but at least several of the cars were well maintained and had clean screens. At least one of the cylinder heads had signs of extended oil change intervals(dark deposits under the valve cover).
 

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Eli, there have been several threads, but this is one of the better ones from an analysis viewpoint:

 

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All of the Japanese motorcycles that I'm familiar with, both air and water cooled, use the cam in plain aluminum bore construction. Those are some high revving engines and many of them, like GoldWings, are ridden many miles.
 

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Actually, GoldWings are not the high revving engines, so not the best example. I have seen numerous 'Wings with over 300K miles on them though.
 

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Nowadays most plain bearings in an engine are an aluminum alloy anyway, so the primary difference between traditional replaceable bearings and ones that are machined in is mostly just serviceability. Presumably Honda determined that the cam bearing surface should last the life of the car, so forgoing replaceable bearings makes sense.
 

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I wasn't aware of the failures where oil level was OK. Hmm. Just because oil level is OK at the time of incident doesn't mean it hadn't been run low in the past though.

Well, the proper way to watch for this is going to be through oil analysis. You'll see a spike in wear metals long before anything snaps off. If we had enough people doing this, we might be able to identify the common theme when galling very first happens.
 
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