Plastic Engine Cases?

[kellysguy]

Please bare with me as I'm new to new saws. Did I read correctly that some manufactures are making engine cases out of plastic, is that right? I've seen where some use magnesium which I figured was for weight reduction from using aluminum. As a former VW guy I'm really not a fan of magnesium but I'm CERTAINLY not a fan of engine cases made from composite materials and that includes carbon fiber!

Help me out here, who makes saws engine cases out of actual metal and what models are they?

I can't bring myself to buy a plastic saw, not now, not ever. I would die if I bought a plastic saw. I hope my older Poulan Pro isn't as I'm gonna puke if so.

[beenthere]

Time that you were dragged into the new world.  ;D

Do wish you well with your search.

I just purchased a Stihl MS362 and so far am very pleased with it. Starts easy, runs great, and handles like my beloved MS361. I like the off switch that flips back into "run" position so pick up the saw, bull the starter cord and going. No lost motion switching to "run". Also like the captured bar nuts that can't roll off and be lost in the duff when changing the bar. Also a great air filter arrangement. The cover pops off and exposes the cyl. head for easy cleaning with a short blast of air.
I think I'm going to like this one real well. Good power and light weight.

[sablatnic]

It is easy, just go for the professional saws, they have metal crankcases. Tanks, starter housings, covers might still be plastic though.

[dougand3]

WATCH YOUR FEET! HE'S GONNA HURL!
All homeowner level saws have a plastic engine case (chassis is better term). Poulan, Husq, Stihl, Echo, Homelite all have them. The engine ITSELF is all metal and installed complete in the plastic chassis. Called a clamshell - it's clamshell like wrapped around the crankshaft. Poulan Pro stopped being pro some time ago. I have a real pro PP380 Super from the 1990s - Metal crankshaft case, that is the saw chassis, that jug/cylinder bolts onto. But any newer PP is gonna be clamshell. The PP5020AV is a very competent saw - clamshell.
So, you have 2 saw types - clamshell and pro construction. And there is nothing inherently wrong with a clamshell saw. They are designed for limbing and mild-moderate firewood bucking. They hit a low price point. They are a little harder to change the jug on - clutch comes off, 4 extra bolts and whole engine comes out of chassis. I just put a new piston/ring in a Husq 141 and it took a little longer than my Husq 55 but not bad.

[JohnG28]

^ x2. Pretty much sums them up. Main engine parts are magnesium or aluminum and the case, tanks etc. is plastic. They work just fine though given they used for their intended purposes.  Not going to run one 8 hours a day for months or years, but they'll cut wood! 

[kellysguy]

I thought I understood but now I'm even more confused. Tell me if this is right:

The engine case that the crankshaft actually spins in that holds the crankshaft bearing; that the fuel/oil mix actually comes in contact with while being blown into the cylinder is aluminum. The cylinder bolts directly to an aluminum or mag case and then that is enclosed by a plastic clamshell that everything else mounts to. Is this correct for the "clamshell" definition?

Thanks for being patient with me. I'm an ASE Master tech and know engines well, just not what's been going on in the small engine/chainsaw world the last decade or so.

[kellysguy]

OK, I see now. I looked up the schematic. I'm gonna be ok. I can handle the clamshell deal. The problem I was having was just a misunderstanding of chainsaw meaning of the word "case".

[beenthere]

Tell us you ain't gonna puke now...  ;D

[kellysguy]

Not puking. "Engine case" in the automotive and motorcycle word has a different meaning.

[Chris-PA]

Older Husky clamshells (and Partner) used the plastic case as the bottom cap of the clamshell - so part of the engine was plastic.  You can puke now!

[sablatnic]

Would be more correct to say Partner (and Husky and Jonsered), as it was a Partner saw from the early eighties, that Husqvarna and Jonsered took over. They were very decent saws to the price, and many are still running. I have a few to use as toss around and do anything saws. Seems to last almost for ever and are nice to work on, unlike many of the newer clamshell saws. We call them hupajos.