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  1. #1
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    Default Questionable engine designs

    I have at times posted here on some very questionable engine designs where a stupid little oversight can be very expensive in the long run. Fore example the flap valves in the intake manifolds of BMW and Toyotas causing complete engine failure when it breaks.

    Yesterday I watched a video of the Ford 3.5 V6 Eco twin turbo engine being stripped. A very nice engine from a technical point except for one monumental slip up. The waterpump sits inside the timing cover! And although it does have a weep hole to the outside, according to the guy doing the dismantling, the majority of failures on these engines in the US are due to the waterpump leaking and water running straight into the sump.

    I have seen countless similar examples over the years and stand absolutely amazed that the designers could not foresee the potential problem!
    There is never a right time to do the wrong thing and never a wrong time to do the right thing!

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    Default Re: Questionable engine designs

    The question I always have is; did the engineer/designer know it is going to be a problem, but had to make a plan to fit a certain budget? Mostly I think it is the latter.
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    Default Re: Questionable engine designs

    Oom Francois, what is your thoughts about many of the newer engines having an open deck block? I would think with the kw/L figures going up, manufactures would rather lean towards more robust designs.

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    Default Re: Questionable engine designs

    There is a degree of planned obsolescence designed into engines and cars these days. And it really dictated by the majority of the market which trend is to trade in after 4 to 5 years.

    This guy does a good video about it. Lots of components that should be metal are becoming plastic these days like thromstate housings, intake manifolds even tappet covers.

    https://www.youtube.com/watch?v=SeMZGICNSMg
    Last edited by Karol; 2021/06/09 at 09:51 AM.


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    Default Re: Questionable engine designs

    I had a look at a shorter video and the amount of work that needs to be done to get to the waterpump is crazy.

    https://youtu.be/25OyZ9NVn7M
    Last edited by Tom13; 2021/06/09 at 09:53 AM.
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    Default Re: Questionable engine designs

    Quote Originally Posted by Kambro View Post
    Oom Francois, what is your thoughts about many of the newer engines having an open deck block? I would think with the kw/L figures going up, manufactures would rather lean towards more robust designs.
    Kambro, I don't think there is a hard and fast rule or answer. Some of the best engines ever produced have been open deck eg Peugeot. But they were not highly stressed engines. I like it for the cooling properties. There are some very reliable diesel open deck engines around but then the sleeves are loose and made from cast iron.

    But yeah clearly it will be less sturdy purely by design. Obviously also critical to have very good gaskets and coolant additives. Too many variables to really give a definitive answer I think.

    I would like to hear Grip's thoughts on the matter.
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    Default Re: Questionable engine designs

    Quote Originally Posted by Karol View Post
    There is a degree of planned obsolescence designed into engines and cars these days. And it really dictated by the majority of the market which trend is to trade in after 4 to 5 years.

    This guy does a good video about it. Lots of components that should be metal are becoming plastic these days like thromstate housings, intake manifolds even tappet covers.

    https://www.youtube.com/watch?v=SeMZGICNSMg
    I don't think the original idea was planned obsolescence, but more a cost exercise in terms of manufacturing cost. I can understand this to an extent, as long as these parts are treated as wearing/degrading items to be replaced after a certain period.

    What I don't understand is where at times the failure of some of these parts, costing a few cents at times, can lead to instant and complete engine failure.

    As an example. I used to own a Land Cruiser 4.5 EFI, widely acknowledged as one of the most reliable engines ever made. One day, during a particularly hot spell and me with a heavy load and towing a trailer, noticed a sudden spike in engine temps. I stopped and found a small little rubber hose, about 50mm long, connecting the heater pipe to the cylinder head, had burst. It sits completely obscured in one of the hottest spots on the engine. Had it not burst, I would have never known about it. It could easily have cost me and engine did I not spot the rise in engine temps in time. I later learned that it is known as the PLHH (pesky little heater hose)or something similar amongst Land Cruiser owners. A simple design change (which was done later one) could have prevented this. But it should have never happened in the first place.
    There is never a right time to do the wrong thing and never a wrong time to do the right thing!

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    Default Re: Questionable engine designs

    Logistics Engineering is a discipline which hinges around 5 phases of design from the conceptual phase through to end-of-life. Core to the philosophy are design for reliability, availability, maintainability and serviceability.

    I would suspect that components of this are incorporated in modern vehicle design but subject to budget and time constraints and the need to get new models into the market at regular intervals. In other words, trade-offs.

    Combine this with engineers and designers who have never swung a spanner as well as regulatory pressures and we see the results you mention in the #1st post Francois.
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    Default Re: Questionable engine designs

    Quote Originally Posted by WernerDL View Post
    The question I always have is; did the engineer/designer know it is going to be a problem, but had to make a plan to fit a certain budget? Mostly I think it is the latter.
    Design faults like this should be eliminated in the LSA (Logistic Support Analysis) FMECA (Failure Mode Eventuality Criticality Analysis) stage of the design. FMECA's are expensive and time consuming so the level of analysis depends on the budget and this is where mistakes happen. When dealing with a myriad of components, simple logic is not always obvious and there are no assumptions. On an engine it should go well down into the PBS (Product Breakdown Structure) though. Another example of not going deep enough are the Ford Rangers headlight and tail light problems.

    Estee, Jouko and other engineers here, correct me if I'm wrong but I believe the only two objects that have had a complete FMECA down to every single component including screws, nuts and bolts are nuclear weapons and spacecraft? Aircraft and submarines go quite deep into the PBS but not all the way.

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    Default Re: Questionable engine designs

    Quote Originally Posted by Estee View Post
    Logistics Engineering is a discipline which hinges around 5 phases of design from the conceptual phase through to end-of-life. Core to the philosophy are design for reliability, availability, maintainability and serviceability.

    I would suspect that components of this are incorporated in modern vehicle design but subject to budget and time constraints and the need to get new models into the market at regular intervals. In other words, trade-offs.

    Combine this with engineers and designers who have never swung a spanner as well as regulatory pressures and we see the results you mention in the #1st post Francois.
    Thanks Estee. I was typing when you posted this.

    Edit: I see there are still about 12 elements of Logistics Engineering.
    Last edited by Olyfboer; 2021/06/09 at 10:32 AM.

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    Default Re: Questionable engine designs

    Quote Originally Posted by Olyfboer View Post
    Design faults like this should be eliminated in the LSA (Logistic Support Analysis) FMECA (Failure Mode Eventuality Criticality Analysis) stage of the design. FMECA's are expensive and time consuming so the level of analysis depends on the budget and this is where mistakes happen. When dealing with a myriad of components, simple logic is not always obvious and there are no assumptions. On an engine it should go well down into the PBS (Product Breakdown Structure) though. Another example of not going deep enough are the Ford Rangers headlight and tail light problems.

    Estee, Jouko and other engineers here, correct me if I'm wrong but I believe the only two objects that have had a complete FMECA down to every single component including screws, nuts and bolts are nuclear weapons and spacecraft? Aircraft and submarines go quite deep into the PBS but not all the way.
    Indeed, I suspect that the width and depth of FMECA/FMEA exercises are narrow and shallow when it comes to automobiles compared to the other industries you have mentioned. The unfortunate aspect with some systems such as those I have been involved in (IC Engines and related systems) is that when we retrospectively doe the FMEAs is that, in some instances, the recommended route is ''Redesign'' which unfortunately, is out of our hands. The best we have been able to do is mitigate where possible with maintenance frequencies, tasks and replacement schedules which as you know, can be costly.

    Conducting the PBS and FMEA is time-consuming and costly
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    Default Re: Questionable engine designs

    Quote Originally Posted by Estee View Post
    Logistics Engineering is a discipline which hinges around 5 phases of design from the conceptual phase through to end-of-life. Core to the philosophy are design for reliability, availability, maintainability and serviceability.

    I would suspect that components of this are incorporated in modern vehicle design but subject to budget and time constraints and the need to get new models into the market at regular intervals. In other words, trade-offs.

    Combine this with engineers and designers who have never swung a spanner as well as regulatory pressures and we see the results you mention in the #1st post Francois.
    Yip, R&D and testing eats into both and reliability (or lack there of) is generally affected by it - I remember reading a comparison report for reliability between certain Honda and Chrysler vehicles done in the US - the correlation between R&D/testing and reliability was very obvious.
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    Default Re: Questionable engine designs

    If you do a full FMECA on a complex high end Engineering Workstation (AKA a PC), you will find that the most likely to fail with the most severe consequences is - A R99.00 Mouse. The reasonable corrective action is to have a spare mouse in stock.

    We paid several million a few years ago to find that out about a mission critical system for the SAAF.

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    Default Re: Questionable engine designs

    Quote Originally Posted by Estee View Post
    Indeed, I suspect that the width and depth of FMECA/FMEA exercises are narrow and shallow when it comes to automobiles compared to the other industries you have mentioned. The unfortunate aspect with some systems such as those I have been involved in (IC Engines and related systems) is that when we retrospectively doe the FMEAs is that, in some instances, the recommended route is ''Redesign'' which unfortunately, is out of our hands. The best we have been able to do is mitigate where possible with maintenance frequencies, tasks and replacement schedules which as you know, can be costly.

    Conducting the PBS and FMEA is time-consuming and costly
    Yes, the common pitfall is increasing maintenance frequency instead of engineering the problem out. This shifts the cost to the user of the product and saves the cost to the producer. Do this too often and your reliability becomes less coupled to higher maintenance costs resulting in the product getting a bad reputation and future designs, no matter how good, being suspect in the minds of the consumer.

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    Default Re: Questionable engine designs

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    Default Re: Questionable engine designs

    Quote Originally Posted by Francois Theron View Post
    I have at times posted here on some very questionable engine designs where a stupid little oversight can be very expensive in the long run. Fore example the flap valves in the intake manifolds of BMW and Toyotas causing complete engine failure when it breaks.

    Yesterday I watched a video of the Ford 3.5 V6 Eco twin turbo engine being stripped. A very nice engine from a technical point except for one monumental slip up. The waterpump sits inside the timing cover! And although it does have a weep hole to the outside, according to the guy doing the dismantling, the majority of failures on these engines in the US are due to the waterpump leaking and water running straight into the sump.

    I have seen countless similar examples over the years and stand absolutely amazed that the designers could not foresee the potential problem!
    Hi Francois

    Hope you are well.

    I know you worked on the 2.5 T2 Microbus for the VW factory so I am sure you are fully aware of the massive design fault with the 2.1 water-cooled VW Boxer engines? They all snapped a conrod at some point and the conrod then went through the block... I trained on these motors as an apprentice and lost count of how many subs I replaced. We could never work out the reason for the conrod snapping? Perhaps you had some insight into this. I do know that the 2.1 was one of the shortest engine production runs for VW ever... perhaps they realized pumping out 82kw from an engine using Beetle engine bin parts was problematic... the other issue was that the cylinder head studs sat in the coolant jacket... and many of them just rusted through. A great pity, as it was a very smooth, very light and powerful engine with a smooth power band.

    Your thoughts?

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    Default Re: Questionable engine designs

    Quote Originally Posted by Francois Theron View Post
    ...according to the guy doing the dismantling, the majority of failures on these engines in the US are due to the waterpump leaking and water running straight into the sump.
    ...
    That is the question here... what weight does the opinion of the guy doing the dismantling hold?

    Quote Originally Posted by Estee View Post
    ...

    Combine this with engineers and designers who have never swung a spanner as well as regulatory pressures and we see the results you mention in the #1st post Francois.
    Not at all conclusive, but a cursory search for "ford 3.5l ecoboost engine problems" does not lead to the waterpump being an issue.

    Could it not be that the benefits of not having any pipes and integrating the water pump into the lump the way it has been done is actually the "best" design overall?

    I can see the frustration involved if that is a problem the owner or mechanic are facing, but it does not seem to be an issue in the grand scheme of things.
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    Default Re: Questionable engine designs

    Quote Originally Posted by Darron View Post
    Hi Francois

    Hope you are well.

    I know you worked on the 2.5 T2 Microbus for the VW factory so I am sure you are fully aware of the massive design fault with the 2.1 water-cooled VW Boxer engines? They all snapped a conrod at some point and the conrod then went through the block... I trained on these motors as an apprentice and lost count of how many subs I replaced. We could never work out the reason for the conrod snapping? Perhaps you had some insight into this. I do know that the 2.1 was one of the shortest engine production runs for VW ever... perhaps they realized pumping out 82kw from an engine using Beetle engine bin parts was problematic... the other issue was that the cylinder head studs sat in the coolant jacket... and many of them just rusted through. A great pity, as it was a very smooth, very light and powerful engine with a smooth power band.

    Your thoughts?
    Darron I have been asked this question before (might even have been you). No I am not aware of a con rod breaking issue on those engines. The studs breaking due to wrong/insufficient coolant additive yes.

    If I have to venture a guess on the con rods breaking I would guess overrevving. Those engines were torquey but didn't like high revs.
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    Default Re: Questionable engine designs

    Engineers very seldom get a completely clean sheet to design an engine, invariably there is some carry over or parts sharing from other engines to save design and manufacturing costs. Seen in isolation something may look stupid (and possibly is - engineers also screw up) but more likely it was a compromise between cost/time both in design and manufacturing.

    Also consider when you are making hundreds of thousands of a component even a small cost saving adds up, so if you can save $10 by casting a part in plastic rather aluminium and you make 100 000 of them a year thats $1mil saved. Me and you looking at the piece of plastic on our car would think why would they try and save $10 on a car costing so much but we dont see the big picture.

    Sometimes things do just get a bit silly, we had a thermostat failure on one of the chev utilities at work and I was amazed to see them stripping the cam pulley and cambelt off as the thermostat housing sit behind it on the engine.

    And then having to drop the engine and gearbox on the Q7 so they could replace a boost pipe, but thats more a packaging issue in the chassis than engine design fault
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    Default Re: Questionable engine designs

    Quote Originally Posted by Fluffy View Post
    If you do a full FMECA on a complex high end Engineering Workstation (AKA a PC), you will find that the most likely to fail with the most severe consequences is - A R99.00 Mouse. The reasonable corrective action is to have a spare mouse in stock.

    We paid several million a few years ago to find that out about a mission critical system for the SAAF.

    ---------------

    Analysis Paralysis comes to mind.
    Thanks Fluffy. Yes, a very cheap component can be a mission critical component and a show stopper.

    The multi million Dollar remote controlled subs in the offshore industry have a pilots chair. Everything on that chair has redundancy on a keyboard or touch screen for the pilots digital inputs and a lever for the analogue inputs, including all the buttons on the joystick and the foot pedals. But the XY axis and inbetweens of the right hand pilots flying joystick is analogue and therefore has no redundancy. It has a long expensive lead time and a 10 minute changeout time resulting in a low system value but high individual component value spare being carried as it cost US$5000.

    But losing its function is a multi million Dollar show stopper so a spare is carried. Pic of the pilots chair and mission critical pilots joystick:

    Click image for larger version. 

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    Last edited by Olyfboer; 2021/06/09 at 11:39 AM.

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