11 replies to this topic

[mike.]

I'v realised that quite alot of minis have a clutchcase breather and a little breather filter on top. Just wondering why my mini has this blanked off?

[mike.]

As seen here -

[Ethel]

Give over, this is just an excuse to show off your gorgeous engine bay, yer not fooling anyone!

Your 998 has a tappet cover with a breather attached; 1275's get the clutch case one instead so they don't feel left out

erm hang on that piccy is of a 1275 - give it back now!

Edited by Ethel, 28 November 2007 - 11:20 PM.

[mike.]

haha no no no thats not my engine bay thats just one i'v found as an example of one with a clutch breather.

Mine doesn't have that and looking at the clutch case doesn't have a hole or mounting point for a clutch breather either so was just wondering is its been blanked off or if it just didn't have one in the first place.

[Ethel]

Never had one, only 1275's do.

[mike.]

Ok Cheers

[Big_Adam]

It's not a clutch breather. It for oil vapor gas ... stuff.

[Dan]

As Adam says it's not a breather into the clutch case, it's into the drop gear case and so the crankcase and gearbox. People fit those little breather filters to the breathers if they like dirty oil, a gunged up engine and a film of oil vapour coating their engine bay, they think it looks good. As Ethel says though 998s don't have one on the transfer case as standard.

[samwell]

and you cant fit one if your brake master cylinder is in the wrong/write place

998s do gain one on the tappet chest covers which is a godsend as its mch easier to change the cam with t'engine in the car. My crankcase does have a raised and tapped area (i.e. ready for studs and a breather) but they do look fit, and VIZARD says all engines need at least two...

[998dave]

It's a breather,

basically reason for them is thus;

Your piston rings never make a perfect seal, so you get what's called blowby - basically exhaust gases passing by the pistons into the crankcase, (this is about 20 litres/minute for a 2 litre production engine - not sure about a mini).

This would pressurise the crankcase, however you can stop it doing so by fitting a pipe back to the inlet, (recirculating gases and fumes), on a 998 this is a take off pipe from the right hand tappet chest cover.

On the 1275 they fitted two breathers, one from the timing gear cover, and one off the clutch casing, these were originally fed back into the inlet manifold to go back into the engine, but now in some cases fed through seperaters, (the black canister), and filters to atmosphere.

Back to the first paragraph, 20 litres / minute sounds a lot, but think a 2 lite car at 5000rpm is passing approximately 10,000litres / minute, so 2 litres is only a fraction of a percentage. On a knackered engine the blow by increases as the piston rings wear, once you get to about 100 litres/minute the odds are the engine will stop fairly soon!

Hope that explains some stuff!

Dave

[alexcrosse]

it is a breather, to deal with the problems of crankcase pressure

[998dave]

it is a breather, to deal with the problems of crankcase pressure

i said that...