FSM Oil Breather

[smchris]

Dear all

I am slowly working my way through an 1961 FSM; this one has an "interesting" oil breather that looks like someone has built from an old aerosol can cut in two and with the two halves re-inserted one inside the other and rivetted together! I cannot see inside the contraption to tell what sort of filtering, if any, is going on in there, but by way of experiment, I took it off and ran the engine. There is no pressure, or vacuum at the breather port on the timing cover whatsoever.

Should I be surprised? Or might this point to a blockage between the timing housing and the main crankcase?

How should I proceed, if at all?

Thanks for your guidance.

Chris

[Billy26F5]

There won't be much of a vacuum, but see if when you put oil in it it comes out or not, if it does your bores are worn, if it stays put just leave it, remember to ensure the rocker cover to air filter connection is clean and seals properly, Dunlop Tractor Spares have new rubber connectors if you need them. The breather is a small oil bath, if you can send a pic of the timing cover we'll see which breather you need. Here's the early one on Billy:

The later one has a smaller diameter and longer mounting tube on the timing cover, the early one has an o-ring
Sandy

[smchris]

TY

I shoved my thumb over the aperture to see if there was inward or outward pressure. I couldn't feel anything.

I've replaced the liners, pistons and rings, so there should not be excessive blow-by in this engine because it's effectively reset to new from that perspective. The rocker to air filter pipe is fine and patent, so there should not be high pressure anyway, but I did expect to at least feel something at the timing cover port.

I think this is a later type breather, but hard to tell owing to the contraption someone has put on there; the stem from the timing cover is quite tall.

Chris

[John b]

Hi Chris, just rebuilt a major engine and there's no pressure at the timing cover or rocker cover. I reckon we must have got it right, fingers crossed!
John

[Billy26F5]

I would check the rubbers on the rocker cover to air filter pipe are good, as if not it won't work properly (it will suck through the cracks instead of the breather). If you don't have an oil spill I would consider it ok as long as everything is well fitted and the air has to go from the breather to the air filter through the engine. I would remove the aerosol can and see what breather you need, so you then have the right fixture and the air going in is clean. The breather needs a clean when the air filter does.
Sandy

[smchris]

Hi Chris, just rebuilt a major engine and there's no pressure at the timing cover or rocker cover. I reckon we must have got it right, fingers crossed!
John

Thanks; does your rebuild still smoke? My still chucks out blue smoke at tickover or when running at about 1000rpm; at higher speeds it's completely clean, unless you put it under load of course and then it blacks a bit. But I cannot fathom where this blue smoke is coming from. Maybe the rings have yet to bed in properly? It's only done about 20hrs since rebuild and only half that under harder load with a big topper, so maybe it needs to carbonise better.

The only thing I did not replace was the valve guides. they were pretty tight, with no obvious play, so I left them alone. Maybe I should have done those too?

C

[John b]

I did change the valve guides on mine, did you put new stem seals on them? Have you re-checked the tappets? If the valves aren't opening enough it will suck more oil past the rings (sorry if i'm stating the obvious, just trying to think of everything) It may well stop smoking once its broken in and the rings have settled. Mine doesn't smoke but it hasn't had any hard work yet. But as the saying goes, black smoke don't mean its broke!
John

[Billy26F5]

You really need to get ploughing, otherwise the load won't be anything like high enough, Billy's engine is very clean when ploughing hard, but when not doing very much he gets quite smokey, a good ploughing session should clear any smoke away, if it doesn't there's more of a problem. You should only get black under an extremely heavy load.
Sandy

[smchris]

I've got a 3m Port Agric topper and some 2ft high grass that gives it quite a work out! When it's thrashing through that it runs clean. But when it's pottering about moving dirt in the bucket it blows blue smoke and produces exhaust fireworks when you rev it up. I think it's just oil left on the liners when not under load; these engines are obviously prone to that. But I thought I'd check... thanks for the reassurance.

[Billy26F5]

That doesn't sound like very much at all for a Major. Try some ploughing, you'll see the load is much higher.
Sandy

[smchris]

This is the attachment point for the timing cover breather on my super:

https://swap.nakeddiscovery.com/s/zyz4BeBoiTqkbfY

[Billy26F5]

That's the late one. They're more common than the early kind. Both are available aftermarket, I don't know if they're any good though.
Sandy