air leak test

[shipscat]

does anyone know how to do an air leak test ? and if so what tools and equipment do you use

[kru251]

Well what are you trying to prove? Leakage past rings at TDC?

[shipscat]

i meant for testing crank seals

[kru251]

Ah right.
Found these ideas that might help.
Good Luck

www.dansmc.com/vacuum_testing.htm

and

www.dtsfab.com/index/index.php?topic=2953.0;wap2

[sbwnik]

Article in Scootering a couple of months back had as much info as you'd need - the Workshop Essentials column.

AKA 'how to make a tool interesting'. Wait for the one on ramps coming soon....

[pxguru]

No one should ever run a scooter after a crankcase split without a pressure test! Although a leaking engine will run the damage can be anything from increased wear to total wipeout. The crankcase pressure is what gets the oil up the barrel.

You don't need any fancy gear. With the engine all assembled there is only one way in and one way out. If you haven't guessed yet, carb and exhaust.

Rubber bung for the carb manifold ( or a flat metal plate and gasket for standard), A big rubber bung for the exhaust (with a bolt through to adjust), a pump adapter for a football and a foot pump with a Gauge.

If it holds 10psi for 5 minutes then you did a good job

Attachments:

[kru251]

If it holds 10psi for 5 minutes then you did a good job !

I feel that way about a problematic SIP tubless wheel rim at present; LOL

[sbwnik]

'Never run an engine without a pressure test'?

Really?

At a rough guess I've built thirty or forty engines, mainly mine, but others as well, and never felt the need to pressure test. Weak seals on new engines don't tend to show up immediately, they need running before they get destroyed.
I know a lot of people who build engines - including some of the top tuners in the country - and they don't pressure test unless they've a suspicion that they need to.

Just out of curiosity, do you teach 'Theoretical engine building' or something like that?

[pxguru]

I am surprised. I would have thought someone who is scared to rev a newly built engine and then run it in for at least a 1000 miles would do everything possible to be sure it wouldn't blow up. It takes 10 minutes to do a pressure test. 99% of the time they are fine. When they are not it is always surprising where the leak is from. There is not a race bike on the track that hasn't had a pressure test.

You have built nowhere near as many engines as me. Maybe only 10%.

[kru251]

Jan 20, 2013 9:46:49 GMT pxguru said:

I am surprised. I would have thought someone who is scared to rev a newly built engine and then run it in for at least a 1000 miles would do everything possible to be sure it wouldn't blow up. It takes 10 minutes to do a pressure test. 99% of the time they are fine. When they are not it is always surprising where the leak is from. There is not a race bike on the track that hasn't had a pressure test.

You have built nowhere near as many engines as me. Maybe only 10%.

You see you need to qualify that really pxgeru.
By that I mean you could have re built a few engines that total 400 because actually you're not much good at it! Now I'm positive that's not the case, but you can see what I mean? It's like the car mechanic who says he's had 15 years experience in the business. Well if he has always done just a few things time and time again it actually means he's had 1 years experience; repeated 15 times!!!
By the way this is not havin' a go at anyones capability; it's just how it can be read that's all

[shipscat]

thanks for your help

[pxguru]

lmao, I can assure you not all of them have been a total success! Including some of the professional ones. I have pretty much made every mistake in the book and this is by definition the basis of experience.

[kru251]

Heartlly agree. I always say to people that the man that has never made a mistake.......has never made anything!