Newbie question - oil cap

[Dauntless]

I can't get the oil cap off my IIA 2.25P... what the? How is it meant to come off?

[Dauntless]

I'm completely serious. It is meant to unscrew, right? Because it's stuck solid.

[dandlandyman]

No, not that one. To remove that, undo the 7/16" bolt in the rocker cover underneath the cap. There should be a similar cap on a 'spout' near the distributor, which is where you're supposed to pour oil in, put maybe some bright spark has removed it. That one just pulls out.
The only 4cyl cap I've seen that screws off is the orange one with paddle on top (identical to Range Rover V8 one) which was fitted to later engines.
The system shown on your engine is meant to be a flow-through crank case vent system. When travelling forwards, air enters through the forward-facing slots, moves down through the engine and exits through the rearward-facing slots in the other cap. In series 3, that system was replaced by venting the crankcase into the induction airstream. When I rebuilt my 2a 4cyl I fitted the side cover, rocker cover (with the orange screw cap) and air inlet elbow from an '83 5 bearing. It works well.
Hope this helps. Happy Easter.

[JDNSW]

I'm completely serious. It is meant to unscrew, right? Because it's stuck solid.

As Dandylandyman says - the oil cap is actually the other breather in the top LH corner of the picture. Just pulls off.

Later models of the engine had a closed system where this cap was replaced with a sealed one looking rather like a radiator cap, with a pipe off it to the Positive Crankcase Ventilation (PCV) valve and into the manifold and the one in the centre was vented into the elbow above the carburetter.

John

[Dauntless]

Yeah thanks for that. Is it ok to replace those caps with filter type clamp-on breathers? If so, how do I remove the one on the rocker cover?

[dandlandyman]

G'day again dauntless. I'm not sure about what you mean by clamp on breathers, but to take off the rocker-cover breather look for a bolt-head under the breather cap on the manifold side. This must be completely removed as it locates a peg in the side of the breather. The cap can then be pulled or twisted out, though one I've done needed a little more persuasion thanks to corrosion. From your photos, though, I don't think that'll be a problem for you.
I didn't see the other cap in your photo until later (going blind in my old age) but it seems to be on the wrong way round. It's supposed to be located by a groove in the tube and a lug in the cap.
Also, somewhere in my stash I have one of the dust-proof caps. It looks like a miniaturised FJ Holden oil-bath air cleaner. I don't have its mate though - the stemmed plug for the rocker cover.

[Dauntless]

I mean something like this:



Thanks for the info mate.

[JDNSW]

I suppose you could, although I'm not sure why you would want to. If you wanted to change the setup, the obvious change would be to the later positive ventilation system.

John

[Dauntless]

I'd prefer to keep things nice and simple to be honest, and I don't want oil vapours going through the combustion chambers, especially if no catch tank is installed.

I'd change to the above type of breather to make them easier and cheaper to replace, and less leakage.

[dandlandyman]

"Less leakage"?
That sounds like your engine's not in the best health. Check your compressions. Just before I rebuilt my 2a's engine, it decided to spit copious amounts of oil out the breathers at 85kmh (pre-overdrive). I ran my compression tester over it and got figures between 45 and 85psi. After rebuild, they registered around 150psi.
General rule of thumb - they should be above 100psi.
Sorry to be the bearer of bad news, but hope this helps.