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twodoorgaz

2.25: best breather arrangement to avoid oil drips?

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Hi.

I'm building a new engine for my IIA. Its a bit of a hybrid, based around a 5MB 2.5 17H petrol block but with the ancillaries / covers/ head / etc from a Series vehicle to keep it looking like a stock 2.25. There is a bit of a thread on it here.

I'm trying to plan it out so that I can avoid oil drips wherever possible - careful assembly is one thing, but breathers are another.

 

There were a number of different arrangement:

  • early ones had breather caps fitted to both the rocker cover and the side oil-fill pipe, which just vented to atmosphere.
  • later ones had both these caps replaced with sealed units, but the rocker cover cap gained a little pipe... and the side fill pipe itself gained anther little pipe.. and both fed back into the intake via an little PCV/Emmissions control unit.
  • Really late ones dispensed with the side fill pipe and just added a second filler cap to the rocker cover.

 

I'm trying to decide on the beat arrangement to avoid drips on my (and my mates') fancy driveways.

 

I think that the best solution would be:

 

  • a side-fill oil filler pipe from a SIII, rather than a SIIA (with the sealed cap and the little vent pipe half way down) would be the best idea to vent the crankcase.
  • Plus a rocker cover and sealed cap (with the little vent pipe on the side) from a SIII would vent the top of the engine.
  • Plus a plain carb elbow from the SIIA (with no pipe to receive the oily mist from the PCV)
  • Plus a simple universal oil catch can to receive the oily mist from both the side-fill pipe and the rocker cover cap, like this:

71L6Mr-JoAL._SY355_.jpg

 

I'll be doing the same exercise with the new axle, transfer box and mainbox breathers - partly for wading, partly to reduce drips and to keep the components a bit cleaner.

 

Does the above sound like the best solution? Thank you.

Edited by twodoorgaz

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if an original oil filled air filter is fitted, would it be suitable to tap into that? (gives the oil fumes a new life as filter oil (just a crazy tought)

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Thanks guys - I'll have a look at the pro-vent. Sounds interesting.

 

Curious thought re: the air filter, though I'm happy to empty a separate catch tank once in a while (helps me keep track)

Edited by twodoorgaz

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6 hours ago, twodoorgaz said:

Thanks guys - I'll have a look at the pro-vent. Sounds interesting.

 

Curious thought re: the air filter, though I'm happy to empty a separate catch tank once in a while (helps me keep track)

I’ve used catch tanks before on old Fords, pretty standard stuff and easy to plumb in.

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