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Leak down test.
Posted: Sat Jun 18, 2016 9:51 am
by 10 inch Terror
Hi all, I knocked up a homemade leak down kit and it appears to work very well. There was a small leak between the exhaust gasket and the cover plate that I made. I sorted that but have now noticed a leak from the side casing which can only be from the crank side oil seal. Now I'm using a compressor via a tyre valve to pump air in as I don't own a footpump or bicycle pump. I'm sure I've read somewhere you need no more than 5psi to do this test. I'm sure when I fitted the crank it went past the seal without popping or damaging it. I took my time and rotated the crank and both it and the seal were well lubricated. I'm hoping ( really really hoping ) I'm just putting too much air in and it's simply just getting past the seal rather than I've blown it out with too much pressure? Could anyone tell me how much pressure these seals ( Rolf ) are designed to withhold before they leak and if it goes beyond it are they fooked? I obviously don't want to strip the whole top end dow
Re: Leak down test.
Posted: Sat Jun 18, 2016 8:16 pm
by Muppet
Re: Leak down test.
Posted: Sat Jun 18, 2016 10:38 pm
by Scooterdude
Ideally you wanna be seeing 7.5 psi without any leaks so if your seeing leaks a 5 I'd say yer proper fooked.
Re: Leak down test.
Posted: Sun Jun 19, 2016 7:25 am
by garry inglis
Hi holty go on YouTube fitting casa ss200 and leak down test he gives the correct pressure I am sure it's only 5to 7 psi or 350hms
Re: Leak down test.
Posted: Sun Jun 19, 2016 6:57 pm
by Speed Demon
Re: Leak down test.
Posted: Sun Jun 19, 2016 7:55 pm
by 10 inch Terror
Thanks fellas. Much appreciated.
Re: Leak down test.
Posted: Sun Jun 19, 2016 8:14 pm
by fairspares
i had a look at the casa video this morning and noticed that after fitting the barrel and sealing it all with yamabond they had an air leak at the mag housing , now it could have been the drive side seal leaking , what they dont show is how long it took them to strip it all down , clean it up and redo the mag housing , so ive been in workshop and made this from an old 150 barrel , ive removed excess fins but didnt have to but as most were broken and had sharp edges , cut the top off the piston dowel it through the barrel and sealed it all up including inlet , now i can check the bottom end first before building up the top end on small block engines , im thinking this way i can also rotate the crank and check for leaks, any reason why this wont work ?

Re: Leak down test.
Posted: Mon Jun 20, 2016 6:53 am
by nellyboyo
As long as its airtight , it`ll work !