Leak-down testing on the cheap

[Sticky]

Today's Sunday SLUK is a tech article expanding on a previous one I did with photos and video of an even cheaper test method.

I actually got this inner-tube method from someone on here but I can't remember who, so hands-up whoever it was, happy to give you credit in the article!

http://www.scooterlab.uk/engine-pressure-testing-leak-cheap-tech/

[CHRIS in MARGATE]

It was Coaster. He did it m'lord !
Simple but brilliant idea. That's how I do it now.

[Sticky]

I'll edit to suit. I hope you are right Chris

[Sticky]

Fixed

[Adam_Winstone]

I like the hand operated bulb and gauge mechanism. Who supplies these? I've already got a set of bungs and plates to use but the foot pump and electric pump that I have don't allow the sort of control that the hand bulb does.

Good SLUK feature

Ta

Adam

[Scooterlam]

It was a guy called Grandpa who had the original idea to use an inner tube on the inlet with the exhaust blanked off and a clamp affair on the other end of the tube.
It was My development to put the other end on the exhaust stub.

[Sticky]

Apologies ScooterLam, will fix again. Good tip

[coaster]

It was a guy called Grandpa who had the original idea to use an inner tube on the inlet with the exhaust blanked off and a clamp affair on the other end of the tube.
It was My development to put the other end on the exhaust stub.

You beat me to it Derek, I couldn't in all honesty lay claim to this idea. I have used it to good effect though and suggested it to others

[CHRIS in MARGATE]

Aha. It was your recommendation I remember and used.
Sorry for any embarrassment and potential loss of royalties !
And sorry too Grandpa.

[HxPaul]

I like the hand operated bulb and gauge mechanism. Who supplies these? I've already got a set of bungs and plates to use but the foot pump and electric pump that I have don't allow the sort of control that the hand bulb does.

Good SLUK feature

Ta

Adam

I use the cycle inner tube method and a footpump,it kept on loosing pressure,I sprayed everywhere and couldn't find the leak.Eventually found it,it was the pump internal seals,I dis-connected the pump and the pressure remained at 7psi all night.

[coaster]

Sticky's article doesn't mention that the piston needs to be towards bdc otherwise you won't test the cylinder head gasket/spark plug seal.

The blood pressure testing kits are available on ebay Adam very not very much, I don't think I paid more that £10 for mine.

[Adam_Winstone]

Good feedback, thanks guys.

[TVSi]

Looks perfect, great way of testing the integrity of your motor.

Quick question, can I ask what size inner tube you used? I feel this will help people who use a stub type exhaust source one that not to small (or big) thanks

[Eden]

Sticky's article doesn't mention that the piston needs to be towards bdc otherwise you won't test the cylinder head gasket/spark plug seal.

The blood pressure testing kits are available on ebay Adam very not very much, I don't think I paid more that £10 for mine.

can be tricky on a piston port motor having it at bdc, although given a few seconds to equalise the air does get round the piston skirt or you can blank the inlet and pump from the exhaust side with the piston at bdc!

[coaster]

....can be tricky on a piston port motor having it at bdc, although given a few seconds to equalise the air does get round the piston skirt or you can blank the inlet and pump from the exhaust side with the piston at bdc!

Yes I think you are right, the piston would be best with the transfers just open? I did wonder about air getting past the rings but then though on a rebuilt engine they might be abnormally gooped up with 2 stroke oil?? TBH, I didn't think too much about it last time I used the method, only heard it mentioned later

Mountain bike inner tube worked for me, £2.99 from Asda.

[CHRIS in MARGATE]

No they've gone up Colin !
About £4 now.

[Scooterlam]

....can be tricky on a piston port motor having it at bdc, although given a few seconds to equalise the air does get round the piston skirt or you can blank the inlet and pump from the exhaust side with the piston at bdc!

Yes I think you are right, the piston would be best with the transfers just open? I did wonder about air getting past the rings but then though on a rebuilt engine they might be abnormally gooped up with 2 stroke oil?? TBH, I didn't think too much about it last time I used the method, only heard it mentioned later

Mountain bike inner tube worked for me, £2.99 from Asda.

as long as the exhaust is open it shouldn't matter as the tube is connected to both inlet and exhaust, another advantage of the tube over dearer plug based kits

[grandpa]

Hi Sticky,
This was the original post
viewtopic.php?f=10&t=140&p=524&hilit=cheap+leak+test#p524
Update just watched the video on SLUK. Not sure why use a blood pressure pump instead of bicycle pump?
Do you have high blood pressure and no bike
Grandpa

PM sent

[Sticky]

...

[Sticky]

A blood pressure pump is better because it only goes up to 6 PSI so the scale is clearer as it drops. If you use too much pressure too high you can turn the oilseals inside out.

A blood pressure pump is better because it only goes up to 6 PSI so the scale is clearer as it drops. If you use too much pressure you can turn the oilseals inside out.