Blocked breathers; a cautionary tale.

[MikeNash]

My Trav's 1098cc engine goes well but leaks/loses oil alarmingly getting only about 100/150 milesto the pint (imperial, that is). I've been going to do something about it for ages but then a visit to the daughter in Newcastle got in the way, so I set off with a couple of gallons of Wilko's cheapest and hoped for the best. Only to find that we consumed over a gallon to complete the 300 mile journey!
And then it dawned on me that the only recent changed I'd made was to block the hole in the back of the air filter casing where the breather from the rocker box connects. (That was to do with airflow measurement by noting the pressure drop along the filter casing nozzle.) But this shouldn't have mattered because there's another breather off the timing cover case. So I stopped the Trav, unblocked the hole in filter casing and then blew down the breather pipe connected to the timing case - and found it almost blocked! So in practice, the only exit for crankcase gases was via the rear main bearing labyrinth - hence the massive loss of oil. And of course, that much oil into the bell housing didn't do the clutch any favours. I've got clutch slip now as well.
Anyway, I seem to have got back to my "normal" oil consumption but now I've replaced the breather pipe from the rocker box with a long piece of hosepipe and hope that this clearer passage will improve it further. The 300 mile journey back from Wallsend to Andover tomorrow will test it!
I'll report shortly, MikeN.

[bmcecosse]

So - is the rocker cover breather connected to the air filter casing? I found a much better method is to make a hole in the aluminium mounting plate for the air filter - and feed the pipe tightly into that hole. The fumes are now drawn directly into the carb, and not through the paper air filter - which soon covers the filter in a sticky mess. Of course - a later carb will have a brass pipe on the side - which is ideal for removing fume.. Is there not a breather on the front cam follower chest cover?? You mention timing cover above - so possibly you have 3 breathers ? On a 1340 Mini engine which was using oil, I used a servo take-off in the inlet manifold - filled it with Araldite, and then ran a 1/8" drill through. Breather connected to this made a huge difference to oil consumption without unduly affecting the running. You really must ensure good ventilation of the crankcase - any pressure pushes oil up past the rings - and of course out of the rear main..

[MikeNash]

As you will remember Roy (since you sold it to me!) this engine has the breather coming off a canister that stands out from the timing cover. (This canister came "pre-biffed" - by you? - to give clearance for the fan.) It's advantage is that the ignition timing marks are at the top making the timing set up much easier. With this and the normal rocker breather in place I thought all was well and (I think) replaced the front cam chest breather cover with a plain one. Error!! The rocker breather, of course, doesn't pass much because it has a sort of restricter hole where it enters the air filter casing.
Anyway, the rocker box now has a hosepipe to beneath the car and we'll take it steadily to Andover this morn and see how we get on. The clutch slip is the real worry. And then it's lots of breathers to be fitted! (And the engine out if the clutch doesn't recover.)
Oh dear! MikeN.

[panky]

You could try spraying a can of brake cleaner into the bell housing, it may shift some of it.

[MikeNash]

Hmm, yes I may try that. Anyway, I'm off now for the 300 miles home. Wish me luck, MikeN.

[midget]

You could try spraying a can of brake cleaner into the bell housing, it may shift some of it.

Yes brake cleaner is a good idea. I used to use Sonax spray cans, but am now unable to obtain, as I think they have replaced it with as inferior product that needs rinsing off.Any recommended alternative please?

[panky]

The one you get from Halfrauds is a solvent and evaporates once it's cleaned the surfaces. I get a similar type from the local motor factors, bigger can less than half the price

[midget]

That was how the Sonax product worked--I'll try it,Thanks.
The currently available Sonax stuff does work BTW, but the need to rinse with water is not required by me.

[bmcecosse]

Mike - you really MUST have at least one of the breathers connected to inlet 'suction' in some way......

[MikeNash]

Well, I got home doing the 302 miles in 6hrs and 10 minutes driving thereby averaging 49mph, not bad when including a 20 minute jam to get past a burning lorry and the long sections of road works with 50 mph limits. The Trav used 1/4 of an inch of oil on the dipstick, and as the distance between the MAX and MIN lines is 13/16 of an inch and that requires exactly 2 pints of oil to cover it, that's about 490 miles to the pint - let's say at least 400 miles to the pint to be on the safe side.
So regarding breathers, a single 1/2 inch bore pipe from the rocker box will get me up to 400 miles to the pint, whereas the 1/8 inch hole in the back of the air filter case will give me only 100/150 to the pint and a lot of oil leaks. No breathers gives me about 30 miles to the pint, massive leaks and a slipping clutch!

You've been warned! Check those breathers! And now I've got to get the engine out to sort the clutch, MikeN.

(And just to add to the fun the petrol gauge decided to contract it's scale to only a quarter of the display so that "1/8 full" is really half full, etc! Corrr!)

[bmcecosse]

Well done!! So the blocked breathers have been the problem all along ? I wouldn't hurry to get at the clutch - it may 'dry up' if there is no more oil escaping. Is there definitely 1" of 'free play' at the pedal ?

[MikeNash]

Do you think it will dry out? I'll give it a while and see if it does. I've plenty of free play on the pedal - a bit too much, actually. The trouble is I'm surrounded by hills (they go up to a thousand feet behind us) and so it'll be a bit of test. But coming home we cruised on the flat at 60 - it was just the motorway joinings and the over takings that I had to be careful. In the meantime I'll put on all the breathers I can and see how it goes.
Can you tell what's inside the canister-breather on the timing chain cover? Gauze? Steel wool? It's bunged whatever it is.
Regards, MikeN.

[bmcecosse]

Some kind of gauze...the Mini lads take the cover off and set fire to it usually... I can't remember - does that engine have the Mini 'tensioner' timing chain - or duplex ? If duplex - you could fit a normal cover and forget about that breather.

[MikeNash]

As best as I can tell, the chain cover is normal. I think I'll swop it for a plain one, but I like the idea of a breather there - a plain pipe soldered on, perhaps. Do you think it's possible to spray brake cleaner up thro' the lever hole into the clutch? And let it drain out of the bell housing's hole at the bottom?
I'll give it a go, I think. MikeN.

Incidentally, as the fuel gauge was playing up, I filled up more often and so have a good grip on consumption. Over the 600 mile journey the Trav averaged 37.5 miles to the gallon. The needle and jet are about 15 years old - due for a change, I think.

[bmcecosse]

You can only try... or perhaps drill a hole higher up to direct the spray onto the assembly... Frankly - I would give it time...

[MikeNash]

Thanks, I'll drive around and see how it goes. MikeN.