Engine designs that have problems 22

[enginesrus]

Since the one thread I started, is headed way off topic, reason for this.
Engine designs that have problems or have had them.
I'll start with the 3 valve Triton.
This guy explains. Has data from others that deal with the same problems.

https://www.youtube.com/watch?v=xcN_WcGr4BU

 

[enginesrus]

B&S 1 cylinder intek aircooled, cam compression release system failures, and head gasket failures. Kohler command cracked crank cases.

 

[thebard3]

My sister's aforementioned Vega not only suffered engine problems. Manual transmissions failed twice. Door and hood hinges were constructed of stamped steel with hardened bushings spot-welded on. The spot welds broke and the doors and hood just kind of hung out wherever they felt like. With a forward opening hood, the hood had a tendency to overlap the front cowling and would then get bent straight up if you weren't careful when opening it. It wasn't a problem for me, but because this car broke down so much and all the guys trying to get sway with my sister by trying to help, I could always tell when someone else had been in there. The in-tank fuel pump failed twice. Just a short list of the litany of problems that I can remember.
The whole thing was an engineering disaster. I'd consider the Vega to be the 737-MAX of automobiles, only way worse. Conversely, my brother and later my sister each had a Pinto. They were wonderful cars by comparison.
Brad Waybright

The more you know, the more you know you don't know.

 

[SnTMan]

My Vega was fairly reliable, as I recall. Now around here the Pintos pretty much all got turned into dirt track cars.

Pretty sure Vegas mostly got turned into scrap

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Compositepro]

"B&S 1 cylinder intek aircooled, cam compression release system failures".

Years ago, this cost me many hours of frustration, and the scrapping of a $2,000 riding mower. Now I find this easy fix:

https://www.youtube.com/watch?v=ggV0wS6VMSs

Just momentarily block the air intake while cranking.

 

[Brian Malone]

enginesrus - I have looked at the youtube videos and various weblinks on the Rotec engine and I am still at a loss to know what/where is the failure mode? The engine design seems quite amazing and compact (for a radial configuration), and it is well suited for its intended use, and the company owner, Paul Chernikeef seems to be engaged in the actual hands-on design, specification, machining and assembly and test of the engines but the horror stories (and near tragic outcomes) presented by many of the videos seem to indicate otherwise. This engine looks beautiful, seems to run well when everything is right. The failures seem to be shoddy materials and assembly rather than an intrinsic fault of the mechanical design. The video you linked points out o-ring/quad ring seal retained with super glue and Paul is quoted as stating they use the glue as standard practice. Is this callous disregard for proper engineering or a lack of understanding of seal retention and the limitations of cyanoacrylates in an environment with fuels, etc.? The video indicates many other mechanical errors such as incorrect lengths on fasteners and shafts. The Rotec looks like an amazing design effort- amazing billet machined components and precision die-castings. Are the engine failures just poor assembly technique? Does Rotec get by with this because the engine is sold as an experimental aircraft engine so it does not have to meet any industry/regulatory certifications?

 

[enginesrus]

The Rotec, not seeing one in person and doing a close study of the parts, and just seeing various video's on them, it looks like there are some not very well thought out parts used, and like you say improper materials and heat treat. It sounds like the customer relations isn't too great either.



Compositepro (Chemical)
Yeah and you can turn it a bit by hand too off compression, to give in a running head start. The big problem is when the parts that broke move like if you go over a bump, and broke parts get bounced into the moving parts, not so good things can happen.
Even repairing those engines is no guarantee it will not break again, the system is a good idea but not built correctly, why is that? Sarcastically its not because of engineering!
Then there is the ill designed cylinder head, block deck interface, that can barely hold the head gasket in place, why is that? Yup engineering disaster.

Engineering Disasters, isn't that what this section here on this site is about?

Engineering failures / disasters end up costing someone something.

There really is no excuse for most of these engine problems nowadays. Do they just not test things and depend solely on a computer simulation these days? I just don't see how else this can happen.
Or is it that there are no more real machinists that do the preliminary fabrication and building these engines, that can point out to the engineer that this won't work well or last too long.

 

[IRstuff]

Design for manufacturability and Design for reliability are all parts of the design process; world's best design is pointless if you can't make and it won't stay working.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

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[SwinnyGG]

Op has very clearly never designed anything for mass production.

 

[IRstuff]

I was referring to the Rotec issues called out in the YouTube video. The problems described are essentially manufacturing defects, but for the company, or the tech support, or the designer to ignore or blow off these problems is a sign of a bad corporate culture, and THAT is an engineering failure. The apparent lack of tolerancing and manufacturing tolerance control is an engineering failure. The apparent lack of manufacturing materiel control/requirements is an engineering failure.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[thebard3]

My Vega was fairly reliable

You said 'Vega' and 'reliable in the same sentence.

Brad Waybright

The more you know, the more you know you don't know.

 

[SnTMan]

LOL, yeah, I get it, but it was. Fairly...

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[BiPolarMoment]

I mean... as long as all four wheels were on holding up the rest of the car and the roof is intact, it is 'fairly' reliable as a rolling storage shed.

 

[LionelHutz]

Op has very clearly never designed anything for mass production.

It should be "never designed anything for Lowes and Home Depot consumer level mass production".

You could build almost any consumer item to last, but hardly anyone would buy it because it cost more than the penny pinched one on the shelf beside it.

Also, calling the quality of a low end consumer grade Home Depot engine an engineering disaster is a big stretch. If it doesn't have the potential to kill then it's hardly a disaster.

 

[enginesrus]

Engineering disaster doesn't always have to be associated with life loss, it can be something that costs someone something. Money, life, their mind, body parts etc. etc.
Again there is just no excuse for the, for lack of better terms, the stupidity of some of the designs, especially when there is an existing design that has been proven, for in some cases almost a century.
It just makes no sense when simple "just look at it" logic is thrown out the door, for example that cylinder head deck interface.

Mass production? yeah the items I worked on where always very expensive, not the normal box store stuff.

 

[SwinnyGG]

'worked on'(whatever that means) != designed and walked through tens of thousands of test hours the products about which you constantly complain go through between concept inception and release for sale.

I could clarify my statement and just say its clear to me you've not ever designed anything using an engineering process, whether mass produced or not. You have literally no idea what's involved, and no idea why the things you complain about on this forum are the way they are.

Credit where credit is due though- calling a system failure on a lawnmower engine an ENGINEERING DISASTER is hilarious. So I guess that's a mark in the plus column.

 

[enginesrus]

The sign of a real professional is one that does not belittle someone else.

Now lets get back to Engine designs. So how come there are some manufactures that have such a difficult time getting roller lifters to last? What is causing this? I know of many engines in the past that used the same that had very long lives.

 

[LionelHutz]

You find a new forum complaint thread somewhere?

 

[SwinnyGG]

@enginesrus I'm not belittling you. I'm not criticizing you personally. I don't know you.

I AM criticizing your approach to whatever it is you're trying to accomplish by posting here.

I'm sure there are aspects of your life in which you're an expert. The area of evaluating the work of engineers is not one of them. There is no shame in that. I'm not an expert in recruiting college athletes. There's no shame in that, but I also don't go to college recruiting forums full of college coaches and tell them all how they're doing it all wrong and how Bear Bryant had it right in 1975 and all that's happened since then is devolution.

You constantly post complaints about all manner of things which seem to be rarely, if ever, based in empirical fact. When you're presented with information contrary to your non-fact-based opinions, you bristle and ignore it.

That's fundamentally not what engineers do, and it's contrary to the value and culture of this forum. You could change that by not dying on the hill of your own opinion, and actually taking the time to read and internalize rebuttals to the things you post. The trend so far seems to indicate that you won't ever do that, but ultimately the only person on this forum who can save your reputation is you.

 

[wayne440]

...some manufactures that have such a difficult time getting roller lifters to last? What is causing this?

Claiming no expertise, my guess is the cylinder de-activation schemes that have (relatively) recently come in to play. My only experience is with the FCA 5.7.

 

[BrianPetersen]

Not all engines that have roller-cam-follower issues have cylinder de-activation. The Pentastar V6 is another one, and it does not have cylinder de-activation.

I have one of those. A new rocker is a $20-ish part. It's a few hours labour to replace if one goes bad. Meh.

(N.B. It's way more labour-intensive to replace a failed roller lifter on a pushrod Hemi. The Pentastar is DOHC, and you can get enough clearance to replace those lifters without fully removing the camshafts - just loosen the camshaft caps enough to get sufficient clearance to get them out and in.)