Timing chain breather

[Tom Rae]

I am looking for information on the internals of the timing chain breather used on A series engine. Has anyone explored one? At first I thought it was a simple "canister" to collect condensate but inside I can see a wire, anyone know its function or is it time to pick up a for a hacksaw? An internal diagram would be really helpful.

Tom

[Exminiman]

Here you go, bit of a discussion on the MG forum. https://www.mgexp.com/forum/mg-midget-f ... n.3797939/

The mesh is usually so clogged up with old oil, hardly any “breathing” is happening - might be worth replacing the mesh on road car, most will just remove it - especially on an inline A Series

If you want to replace mesh, here is some special “Swish Tune” stainless mesh https://www.amazon.co.uk/Pack-6-stainle ... 6523&psc=1

[Tom Rae]

Thanks very much exminiman, very helpful. If I do replace the mesh, I am not clear how it is held in place?

Tom

Swishtune.....? LOL

[Peter Laidler]

I have a recollection that the top of the breather thinggy was sliced off. Cleaned out - yep usually full of hardened oily gunge - and a threaded insert soft soldered into the can and the top replaced with a screw-on cap.. Insert new washing-uo scourer pads as per Marc said. Cap screwed on and better than new - and serviceable too!

Most sensible idea to me. As for the screw threaded bits I'm sure that they are available off the shelf at plumbing fittings suppliers

[Tom Rae]

I have a recollection that the top of the breather thinggy was sliced off. Cleaned out - yep usually full of hardened oily gunge - and a threaded insert soft soldered into the can and the top replaced with a screw-on cap.. Insert new washing-uo scourer pads as per Marc said. Cap screwed on and better than new - and serviceable too!

Most sensible idea to me. As for the screw threaded bits I'm sure that they are available off the shelf at plumbing fittings suppliers

Cheers Peter, sounds a good plan, best of both worlds.

Tom

[Desmodromic]

I've done a couple of these recently, and the mesh is held in place by a bent wire clip at the bottom. Roughly 'W' shaped, it can with care be removed, and replaced. Access is from the inside of the timing cover. You need some long nosed pliers and a small pick.

As others have said, most people who go to this length just don't replace the wire mesh. But it can be done.

[Tom Rae]

I've done a couple of these recently, and the mesh is held in place by a bent wire clip at the bottom. Roughly 'W' shaped, it can with care be removed, and replaced. Access is from the inside of the timing cover. You need some long nosed pliers and a small pick.

As others have said, most people who go to this length just don't replace the wire mesh. But it can be done.

Thanks, I have found the aforementioned wire W and I have ordered the stainless Swish replacement mesh (or pot scrubber), no expense spared! I am currently building an A+ engine and I am anxious to minimise oil leaks, is it desirable/possible to maintain negative crankcase pressure?

Tom

[Desmodromic]

Certainly desirable to have low or negative crank case pressure. I fitted an additional breather in place of the mechanical fuel pump location on my A+ block. I run an electrical fuel pump so it was an easy option.

[Terence]

If you intend to use this timing cover on a MKI you will find that it will clash with the plastic rad fan. Steel fan might be okay with some extra spacers on the water pump.
I ended up sourcing a mechanical fuel pump breather, they are not commercially available, so fabrication is required.
The other alternative is to slice the canister & weld a flat plate to reduce the width.

[Exminiman]

Certainly desirable to have low or negative crank case pressure. I fitted an additional breather in place of the mechanical fuel pump location on my A+ block. I run an electrical fuel pump so it was an easy option.

Ditto

https://www.med-engineering.co.uk/billet-fuel-pump

[Terence]

Ditto

https://www.med-engineering.co.uk/billet-fuel-pump
[/quote]

Nice! Didn’t know these were available.

[jayare]

That looks like a Retrosport one - also available direct and in a choice of colours: https://www.dsnclassics.co.uk/retrospor ... sport-5-8/

They also do one for 1/2" hoses,

JR

[Desmodromic]

This is the one I fitted to my race engine https://www.minimania.com/part/C-2A265/ ... p-Mounting

Works great.

[Tom Rae]

If you intend to use this timing cover on a MKI you will find that it will clash with the plastic rad fan. Steel fan might be okay with some extra spacers on the water pump.
I ended up sourcing a mechanical fuel pump breather, they are not commercially available, so fabrication is required.
The other alternative is to slice the canister & weld a flat plate to reduce the width.

Cheers Terence however it is for an inline application with a thermostatic fan.

Good tip on the breather/fuel pump fitting too, now on my (long) list.

Tom

[Desmodromic]

... I am currently building an A+ engine and I am anxious to minimise oil leaks,...

Tom

One more thing to mention. Do fit the later type crank oil seal for your timing cover. For example: https://www.minispares.com/product/Clas ... o%20search these fit both early and later timing covers but definitely give a better seal.

[andy1071]

I seem to remember, I think Vizard, recommending that you have a baffle-plate arrangement between the fuel pump vent-adaptor and the camshaft, to prevent oil being flung/ from the cam/pump eccentric, and drawn up the vent pipe...?

[Desmodromic]

Yes you are correct. The MiniMania one that I use is baffled. I have not seen the insides of the MED or Retrosport ones.

[Tom Rae]

Yes you are correct. The MiniMania one that I use is baffled. I have not seen the insides of the MED or Retrosport ones.

There is no baffle on the Retrosport one.

Tom