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Discussion Starter #1 (Edited)
so my buddy called me up today and told me his simplicity pro 36 from 2004 with a 13hp intek would not start, it would only spit sputter and backfire. so he went to look at the valve train after checking the flywheel key, and this is what he found!



A bent ALUMINUM, NOT STEEL PUSH ROD. Now come on, even my predator engines have steel push rods. he told me his son tried to start it before he got home and may have flooded it, but still even if that was the case it should not have bent like this even from being hydro locked. after further research i found out that they revised the part twice. the engine is a briggs and stratton 3bsxs.3422ht from 2004 with very little hours on in it, probably less then 100. anybody ever seen anything like this before, because i sure have not until now. must be that briggs and stratton quality!
 

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I have not seen it, but I had somebody buy a 420cc Predator engine from me about 6 weeks ago and he told me that it was going to replace a Briggs engine on an Ariens snowblower that kept bending pushrods (according to him, his dealer told him not to keep fixing the Briggs nor to buy another Briggs but to get a Predator 420cc instead, that he'd be better off doing that as they were having a lot of issues with the Briggs engines).
I was ONLY told this.
 

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Discussion Starter #3
thats the same thing i told him, order the push rod set and buy a predator 420cc with the money he makes from the briggs. i think he can get 400 for that briggs easily
 

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I've seen it TOO many times, mostly Briggs with those famous Aluminum Pushrods, but usually on the Vertical Crankshaft engines in lawn tractors. What I've found is the Valve seizing in the Valve Guide. Doesn't take much to bend that straw at that point. I will put a cylinder head on it, if the engine and or equipment is worth it. Lack of maintenance or overheating will cause the valve train damage. Or you could roll the dice and toss in a push rod...... If the part is superseded, they obviously see a problem....OR trying to hide a bigger problem. GLuck, Jay
 

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Imagine that Engineer who though that... "Hey, aluminum pushrods may save us .09 cents an engine, let do it" Brilliant
Except it wouldn't have been an engineer who thought of it, it would have been an accountant! ;)
Or a manager..

Then the word came down from on-high about the great money saving idea, and the engineers knew it was insane, but they were forced to go with it.
Engineers want the best, but often have to work with sub-par ideas due to forces beyond their control.

Scot
 

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Yeah - it's the only drawback to an otherwise good engine. You have to be diligent about maintaining the valve lash adjustment on them...... if you let it get the least bit sloppy this is the result. The minute you have one that hesitates to start quickly, check the adjustment. They go out of tolerance way to easy...... IDK who the genius was that chose to use aluminum, but I'd like to think they specified some type of alloy that could hold up, and got something else that China thought they could get away producing.....? Humpf....... wish they would just stick to tried and true rather than try and save a nickle. I think we'd rather pay $1 more and get quality!
 

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Um... I'm no big B&S fan, but the reality is that aluminum pushrods probably don't cost any less than steel ones. The cost of the raw materials is almost the same, and machining each is pretty easy - depending of course on the particular alloy used. It's possible they save a tiny amount of money on shipping as the finished engine will weight slightly less.

And there's nothing intrinsically wrong with aluminum pushrods... years ago I had a BSA motorcycle that used them, and it could run at 10,000 RPM all day long.

So my guess is there's something else going on here. Valve stems binding in guides, excess valve clearance allowing rockers to move out of position...? Or possibly the pushrods are just underdesigned... too small of a diameter or a too-soft alloy.
 

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Discussion Starter #9
i dont think theres anything else mechanically wrong with this engine, this guy maintains his machine and engine religoiusly
 

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In the vertical shaft Briggs engines the aluminum pushrod can be replaced with the steel exhaust pushrod. Not sure about the horizontal shaft engines, but a simple measurement would tell.
 

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All the vertical Intek engines I've worked on have headgasket issues...always blow next to the pushrod galley. They all have one aluminum and one steel....don't know why. I see many with broken rocker arms....sometimes along with the bent aluminum pushrod. Always an easy fix, and I get the tractors cheap because the motor is shot!
 

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Steel or aluminum that would of bent. Where do you think the energy, between the rotating mass of the crank weights and flywheel, from a locked up piston is going to go? If the push rod didn't eat said energy then cam or valves would have.


Also, contrary to what has been stated by armchair mechanical engineers (sorry but there are a number on here) aluminum is not chosen because its cheaper, they use aluminum to prevent valve lag. On some engines they use 1 steel and 1 aluminum, the reason is that the valve springs are always stiffer on the steel side and don't require it. There are also engines where both are aluminum. The ultimate goal is to improve emissions and performance THEN save the nickels. When it comes to the ching dong wang engines they just save the nickels (aluminum stock costs considerably more than steel-not less, machining it in a mass production environment is a wash).


That was a very nice snow engine for its day. Motors like the cheapo Predators are the primary reason they shut down domestic manufacturing of snow blower engines which obviously makes threads like these very ironic.
 

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Yes you are probably right. I am an Engineer, I should know better. The bean counters dictate what we can design!


Except it wouldn't have been an engineer who thought of it, it would have been an accountant! ;)
Or a manager..

Then the word came down from on-high about the great money saving idea, and the engineers knew it was insane, but they were forced to go with it.
Engineers want the best, but often have to work with sub-par ideas due to forces beyond their control.

Scot
 
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