Motor Mower question (yet another!)

Oh many filters run with a coating of oil..if you use a coarse mesh like steel wool, that makes the dust stick.

modern paper filters have finer pores so normally dont need to

Interesting, as in another post I say that I've just cleaned the filter from such a mower. What is your filter made of? Mine's sponge and I would imagine that it would get pretty blocked by oil and be impossible to clean again without a solvent. I brushed off the foam then used a good vac. on the dirty side and there's significant 'drag' already.

I have most certainly come across foam air filters which need to be oil-covered. (I wanted to write "dampened with oil" but couldn't think of a way of saying it that made sense!)

Yes - you do have to wash it out, IIRC with paraffin. And the engine should, at least originally, have been set up to cope with the drag that the whole filter+oil causes.

In that case I'll try it. The hunting that I'm getting might be caused by lack of oil on the filter /except/ that the filter was already dirty and cleaning it had no effect.

I.ve not oiled a car filter in years...

I think my mower is a paper thing and not suitable for oiling

Many lawnmower engines are regulated by a governor and if that is sticking then you will get hunting

Exactly! Having acquired this old mower a few months ago, the first thing I did was take out the old filter element (which seems to be made of foam rubber), because it was soaked with oil (NO WONDER it smokes when it's running, I thought!), then I washed it in paraffin, then in detergent, then carefully dried it out. I figured it was oil-soaked because of some previous trauma in the engine's life.

Now, having tracked down B&S's manual, I find:

"Take air cleaner apart. Wash Oil-Foam element in liquid detergent and water. Squeeze dry in a clean cloth. **Saturate** [underlined] Oil-Foam element in engine oil and squeeze in a clean cloth to remove excess oil."

Since I've now bought a new element from a proper dealer, I assume I have an "Oil-Foam element".

I have the official B&S word on this, so I shouldn't have any worries, but (as always) I thought I'd come into the "pub" and get some reassurance from me mates, before taking such a bizarre step!

John

Further to this:

I think I'll check with the dealer again: it's possible that B&S used to use some kind of special foam, then switched to using a cheaper more ordinary foam rubber. It's certainly very soft and dense, to be soaked with oil.

J.

Some of the best air filters in the racing and motorcycle world made by K & N and they use oil and foam see

Didn't or don't K&N air filters need oil? Im sure this is actually normal with foam air filters.

I remember that my late father bought a Suffolk Punch lawnmower 48 years ago, and we had to oil the filer. So, things don't seem to change much in the lawnmower world.

I used to have a B&S 3.5HP mower, and that required oiling the filter as you describe and then wringing out. I did it about once a year. I washed it in petrol and dried it beforehand. It lasted about 30 years, until the body of the mower rusted away. The engine was still perfect, but couldn't find anyone interested in taking it.

The oil should not be dripping as in soaked with oil, it should be oily to the touch. Look at extractor fans and see how the dirt sticks to the greasy ones but not the dry fans.

they sold a specail 'HiFi' oil to oil em with :-)

You put some in, and then squeeze it several times, both to remove excess (if there isn't any, you didn't use enough), and to spread it uniformly throughout the foam.

Yes, you're are showing your youth!

But they are normally paper. Oil would block the pores of a paper filter.

Cars are optimised for performance. Mowers are optimised for cheapness, and routinely use technologies long abandoned in car circles

NT

I think there's a case for saying longevity rather than cheapness, though

- I mean yes, they're basic, but basic is all you need when you're not optimising for performance, and makes it much easier to diagnose and fix faults when something does eventually go wrong.

In this specific case, maybe avoiding a paper filter is a really good idea when mowers are often left to fester over winter and any such filter would be liable to mould or other damp-related damage?