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Yesterday, I went to the dealer to buy some parts. In his shop, they were repairing a B&S 305 cc. As I'm always curious, he showed me the parts he had to change inside the motor. The motor had a cam problem. The cam gear is made of PLASTIC press fit on a metal shaft. The cam lobes are even made with PLASTIC !!! I never thought seeing such cheap parts inside an engine. The cam gear lost some teeth. I'm still amazed by what I saw. Unbelievable !
 

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I don't remember what the other parts are made of. But the Honda EU2000i uses plastic cams, I'm pretty sure. It's an OHC engine, not OHV, if that matters (timing belt, not pushrods like with an OHV).

I'm sure they had their reasons, though it's not my first choice of materials. With that said, they can apparently run for thousands of hours, so plastic isn't the kiss of death, anyways.
 

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The low end Kohlers are infamous for plastic internals that fail catastrophically. I haven’t heard of Briggs with plastic internals but I’m not terribly surprised that the low end engine have all sorts of cheap cost cutting measures implemented.
 

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The retailers ( big box ) etc want to sell at a certain price point. Hence have to be manufactured to a certain price point. Cutting costs for at least a decent profit. End result disposable JUNK!!
 

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Not a new idea. Back in another life when I was bending wrenches for Generous Motors they built untold numbers of small block 305/350 engines with nylon or some type timing gears. They lasted a pretty long time. Ford, too, I just found out.

 

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Shoot. Nothing new by a long shot. Back in another life when I was bending wrenches for Generous Motors they built untold numbers of small block 305/350 engines with nylon or some type timing gears. They lasted a pretty long time.
They did, 75,000-125,000 miles but the off the market replacement were metal.
 

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Plastic has been used for a couple of reasons in major engine parts: both less noise than metal on metal and less friction (which means less fuel or more usable power).
 

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Sorry I will stay with metal and good oil. Plastic BS should only be used on externals, not internals where engine failure would result because of $2.00 worth of plastic.
It brings to mind the bearings that were mfg. with nylon cages that would cause a $3500.00 transmission to fail at 35000 miles or less and was not covered under warranty because it was deemed a wear item, and so many other things.
IT JUST DOES'T HOLD UP.
 

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Whether cam gears for Ford and Chevy having plastic teeth, the guide adjustors on the cam timing chain on the Ford 4.6 are also plastic. I'm sure there's a lot more plastic parts in engines of makes. With the proper materials and durability they should also last at least as long as metal parts. There will obviously be exceptions to the rule but most are done to a point for both price and durability.

that's my belief and I'm sticking to it.
 

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Metal isn't always better in every application. Nylons of various strengths are used constantly in modern engines to reduce noise and friction. Briggs has been using them for decades as have Honda, Kohler, and Kawasaki. What do you think a vehicle's timing chain is tensioned against and riding against?


On the dealer end all I can tell you is I never saw the phenolic cams fail unless something else was severely wrong (over speeding, no oil, or compression spike). I did however submit a ton of warranty claims for LCT quality problems.
 

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I could understand for chain tensioner guides or maybe for gear cam even if I don't like that for gear but for cam lobes, no way! This is only done for cutting costs and customers don't win anything with such cheap parts. Repairman told me that these plastic gears often loose their teeth or the gear turn on the metal shaft (press fit) so timing becomes bad. About other plastic parts, he told me some hydrostatic transmissions made with plastic which cost $700 to replace because they were failing at high rate. That's progress.
 

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You think that's bad. Mercury Marine (yes, that Mercury) made a very popular and very successful series of 200HP, 240HP, and 250HP V6 2-stroke engines in the late 90's and early 00's that were used in both outboard (where I think they were called the Max series) and inboard (jetdrive) applications. Those engines cost about $10K each. The survival of that engine was based entirely on an oil pump drive gear made of plastic! Being a 2-stroke, if that gear failed or lost a tooth - and they often did - the engine lost ALL LUBRICATION with predictable and disasterous results. It was so well known that many people simply started premixing their fuel+oil right in the tank rather than take the chance.


Bad enough to lose a snowblower engine. But betting a $10K engine on a plastic gear? Seriously?
 

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I could understand for chain tensioner guides or maybe for gear cam even if I don't like that for gear but for cam lobes, no way! This is only done for cutting costs and customers don't win anything with such cheap parts. Repairman told me that these plastic gears often loose their teeth or the gear turn on the metal shaft (press fit) so timing becomes bad. About other plastic parts, he told me some hydrostatic transmissions made with plastic which cost $700 to replace because they were failing at high rate. That's progress.
I was in a shop for over 10 years. Cam failures were practically non-existent in the grand scheme of things. I'd bet its similar for your local shop but most guys have a predisposed bias against anything they think is cheap. If the material is good enough to tension a timing chain for the life of the engine (generally) then im sure its perfectly suitable for flipping some small engine lifters for a few hundred hours. If there was an issue then every established manufacturer wouldn't be using it, but by in large they do.

Fun fact, even the Model T had a permanently engaged helical nylon drive gear to spin the generator.
 

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Whether cam gears for Ford and Chevy having plastic teeth, the guide adjustors on the cam timing chain on the Ford 4.6 are also plastic. I'm sure there's a lot more plastic parts in engines of makes. With the proper materials and durability they should also last at least as long as metal parts. There will obviously be exceptions to the rule but most are done to a point for both price and durability.

that's my belief and I'm sticking to it.
The Gears on these engines are made of Nylon. Almost as tough as steel.
 

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So you would be ok with them using nylon gears in the auger drive gear box on your $2000.00 snow blower.

Like I said I will stay with steel. That is why I would now rather rebuild a old engine and update the carb and ignition ..

As far as LTC goes , I have had and seen more problems with sowasaki and briggs in the last 8yrs than than I have with LCT, and I am in an area that is pretty saturated with equipment that runs products with the LTCs.
 

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My dad was a model maker at GM (Tech Center, Warren, MI) and two brothers were engineers at GM (Warren, MI). My uncle was an engineer at Ford and a cousin is an engineer (about to retire) at Detroit Diesel and a friend is an engineer at Chrysler (Daimler)..It's always about the money.

They all say/said the same basic thing about upper management:

"How can we make it cheaper!".

Makes me glad I never went into mainstream automotive design.
 

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So you would be ok with them using nylon gears in the auger drive gear box on your $2000.00 snow blower.

Like I said I will stay with steel. That is why I would now rather rebuild a old engine and update the carb and ignition ..

As far as LTC goes , I have had and seen more problems with sowasaki and briggs in the last 8yrs than than I have with LCT, and I am in an area that is pretty saturated with equipment that runs products with the LTCs.
You're talking apples to oranges. Camshafts are under no shear load unless something else malfunctions. Governor gears have been plastic for even longer. Again if you go shop a vehicle, be it a econo-sedan or a high end sports car, and the timing is chain driven (as most are anymore) you're depending on the exact same family of materials to prevent that very expensive engine from self destructing....for hundreds of thousands of miles and thousands upon thousands of hours of operation.
 

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the cams only got to last till warranty is over and then it is your problem lol. with how disposable and cheap most things are it is not surprising that they are making them out of plastic. you are lucky if a snowblower lasts you much more than 10 years with how much cheaper they are made. i really can't say if a plastic cam is better or worse than a metal one. first snowblower i owned came with a broken camshaft and crank gear. transmissions failing also seems to be a pretty big issue on new machines. i really don't even understand how some designer even thought a good old trusted and simple design needed to be changed.
 

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For most things, I care more that the part was well engineered and that the engineers made a well informed choice of material rather than what they actually decided on. I'm sure a cam made from an appropriate plastic that had significant engineering effort put in and was tested thoroughly will be more durable than a metal cam that was made to the standard of "yep, that looks like a cam"
 
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