Why?

[Tannin]

Yesterday I spent the afternoon servicing the machinery.

I changed the oil in the tractor, cleaned the air filter, washed out the fuel filter, checked the transmission oil, checked the hydraulic lines over for leaks, and greased sundry bearings. Oh, and replaced the oil filter.

Then I changed the oil in the ride-on mower, cleaned the air filter, greased sundry bearings, and fitted a new oil filter.

Then I changed the oil in the push mower, thought about adjusting the throttle cable but decided it was close enough for now. B had already fitted new blades a couple of days ago. No oil filter, didn't replace it.

Finally I changed the oil in the mulcher - a largish machine with a 9HP Briggs and Stratton motor and decided nothing else needed doing just yet. Again, no oil filter to replace.

So if a car engine needs an oil filter and a 24HP tractor engine needs an oil filter and a 15HP mower engine needs an oil filter, why doesn't the mulcher have one, or the small mower? In short, why don't small engines have oil filters?

(Feel free to add your own small mysteries of life, especially the ones that you can't just look up on Google!)

[stui magpie]

Wild shot, were the small engines 2 stroke?

[Tannin]

Nope, all four strokes. Most of the other engines are two-strokes (chain saws, brush cutter). There is a four-stroke fire pump, it doesn't have an oil filter either. That's just back from being serviced by a pump man, so I didn't need to touch that one.

As a matter of interest, one of the chain saws is actually a four-stroke which acts like a two-stroke. It runs the usual two-stroke fuel/oil mix and sounds odd for a chain saw, but for all practical purposes you can treat it as a two-stroke. Stihl have a blub about them here: http://www.stihl.com.au/4-mix-engine-lightweight-and-with-good-lugging-power.aspx

[luvdids]

I have machinery that needs servicing.

Oh wait.

This isn't the Bored Board.

[David]

You know that thing I went to on Friday night? Apparently there's another one in three months.

Er... right. Tannin. Mowers. Please carry on!

[3.14159]

[3.14159]

[Tannin]

Brilliant 3!

So what you are saying is that small engines tend to rely on having a wet sump with sufficient thrashing around by the reciprocating components to splash-lubricate? (OK, you didn't say that, I'm just trying to visualise how it works.) And this is why they don't need oil pumps, which in turn is why they don't need filters. Yesno?


Oh ... "reciprocating components". Sorry about mentioning that, David. I trust you didn't unintentionally lubricate anything on reading that. You can do your zip up now, ol' chum, the topic is not, repeat not night clubs, it is small engines. Which is an erection-free zone. Unless they happen to be chain saw engines, of course, in which case our old mate 3. becomes a little over excited.

[Tannin]

By the way, I regularly use a different small mower to take care of a steep bank. It's quite difficult, and every now and then I lose control (no, not that sort of control, David!) and do a barrel roll down the hill. It hates being upside down! Blue smoke everybloodywhere!

[Wokko]

[stui magpie]

[3.14159]

Yes.
Big engines need a pump to circulate the oil to the top of the head where it drains down lubricating all the parts and helping to cool the engine.
(It's also why 2 strokes are limited in size to not much more than a couple of hundred ccs).

[Mugwump]

[stui magpie]

[Tannin]

Thanks 3!

I know a lot of people don't, but I actually rather like two-strokes.

Especially this one.




I rather suspect that this particular two-stroke has an oil pump though.