Vacumm leak

My mistake...I thought it was a petrol motor

Ok, thanks for the replies so far. As soon as I get the chance I will tilt the cab and go searching for all flexible lines and measure the OD of the pipe they connect to and the length I need and start replacing them and while chasing the lines along I will find the 'check valve' (one way valve) and get another one of them too. I will do as suggested establish the booster system I have in Lorry and carry out the test suggested.

My next question in doing this is to establish whether silicon vacuum hose is legal to use on road registered vehicles. I see I can buy Australian made product and up to 1/2" bore but the popular size seems to be 3/8".
So is a silicon made hose legal? It is sold as a vacuum hose but you know how the regulations change all the time without notice.

Also do you think that the new hose I fitted from the reservoiur to the master cylinder is correct? It was labelled as auto transmission fluid hose.

CobAdog
gudday m8
The vacuum hose I have seen has a thick wall and made up of a few cords to stop it from
squash n in wards from the vacuum
if the silicon V: recommends it for a vehicle vacuum system so B it

cya

Cheers Swishy for the added info.
I noticed that vacuum lines are reinforced with a webbing of some type. I thought that I would stop by the workshop that does my rego inspections and ask 'HIM' as he is the dude to give it the tick of approval. His reply was I was being pedantic about the subject. FFS, all I wanted to know was is it legal? So I will bypass the silicone vacuum line made in Australia for the purpose so he cannot knock it back next year for the 'health check'.
Each day I plan to start investigating the leak work gets in the way of resolving it so as soon as that stops bugging me I can get on with fixing the issue.

I can't see any reason why silicone vacuum line would not be acceptable (or why it would be even questioned).

All I know is dont use rubbishy green garden hose...........it will suck flat and melt too.......I used it on my first Inter back in 1966...........first load ,the line melted ,no brakes ,as I was coming down the steep pinch from the old Gabba railway yard onto Ipswich Road...............had to keep on the job tho,so I drove without a booster for a week before I found a decent bit of rubber hose.

Hi Oilman,
I was the one questioning it as I did not want to go to all the trouble of replacing the vacuum lines with something that he could possibly knock me back on. I so hate doing a job twice.
So I asked a bloke who had the local brake shop for quite a long period of time and he said there is no reason he knows of that would make it illegal but pointed out if the rubber ones there now re original they have lasted 28 years. So I will replace them with rubber and then it's done and Mr Inspector cannot have a hissy fit.
It was suggested that it is possible that some silicon vacuum tubes can suck in and that would cause the same problem you had John and as usual at the most inappropriate time.
Next was the question of using automatic transmission flexible hose for the brake fluid line. The answer is yes it will last but I can buy the proper stuff locally at around the same price per metre so I will remove the ones I have and measure the extra one for the clutch and buy enough to replace them both.

cobbadog, Are there any Dairy's left at Coopernook??
All the Milking machines rely on vacuum & have plenty of Hose...
Ask at the local Rural Supplies, or bail a Cow cocky up at the Pub & ask Him..

All the diary hoses are too big in the bore. I can buy rubber hose in town but it comes as 9mm. I will have to dip one end in hot water and stretch it open using a tapered tool to get it to fit the larger ends.
Some of the metal pipes measure 12mm going via the rubber hose down to 10mm. Others are 10mm at each end so that is easy. The exhaust brake hose is 10mm down to 8mm. Then I started measuring other vacuum hoses a lot larger and most are a right angle hose about 70mm long in each direction and fit to a 15mm metal pipe but the rubber is very thick and od measures 20mm. Then there are a couple that have a slight curve so a straight piece will do the job and there are 2 of them but have an id of 19mm.
There is nothing like standardizing things is there?
I will buy some 9mm stuff and start with that and see how I get on. Won't have hose until next week after a trip to town. I know I don't mind a challenge but sometimes you feel like revenge is sweet by mixing up pipe sizes with one hose. Spare parts rip off is what it sounds like.