Leak-down testing on the cheap

[Strummer10]

Anyone know what pressure you should use on leak down test on lambretta in the mmhg scale ??

[Strummer10]

Leak found on spark plug when fully tortured down. Any idea on remedy, plus mammoth head on top end so impossible to check the seal there

[Paul_from_Thornbury]

Just rebuilt my RT195 kit with the Meteor piston, was convinced on previous build I had an air leak as engine would often run on as throttle shut off. Did the bicycle tube method with an eBay blood pressure bulb. I had a leak and checked all sources for it and couldn't find it. Mine too was the spark plug. I have ground out my head to accommodate a CHT temperature sensor so I had removed the spark plug crush washer. Tried with a plug and crush washer with same result, so in the end I used a bit of Hylomar on my CHT sensor copper ring and it sealed.
I'm sure there must be a better solution than this.

[Strummer10]

Thanks I'm pressuring it to 5 psi (248 mmhg) and within a minute it's dropping to 40 mmhg and plug seems to be the culprit thus far

[Warkton Tornado No.1]

Leak found on spark plug when fully tortured down. Any idea on remedy, plus mammoth head on top end so impossible to check the seal there

Recently I leak tested an engine & the leak was also around the spark plug.

With a solid copper washer, the leak disappeared.

However, I prefer the fact that sealing washers are captive on spark plugs & the loose, solid copper washers are too easy to forget/lose.

So, I wound off the standard sealing washer (which is folded metal) & put it on the other way up (the joint toward the plug) & it seems to seal....Touch wood!

[Strummer10]

Thanks Wakton I will give that a try....

[Storkfoot]

I have a bought test kit with various size blanking plates for various size rubber manifolds. They work well. I now wish to do a leak test on a standard engine. Has anyone successfully made a blanking plate for a standard 175 inlet manifold which is 28mm outer diameter? Or, does anyone know someone who sells them.

I know I have the choice of just using an inner tube but, in my experience, they don’t seal as well.

[Toddy]

I have a bought test kit with various size blanking plates for various size rubber manifolds. They work well. I now wish to do a leak test on a standard engine. Has anyone successfully made a blanking plate for a standard 175 inlet manifold which is 28mm outer diameter? Or, does anyone know someone who sells them.

I know I have the choice of just using an inner tube but, in my experience, they don’t seal as well.

Paul I found the inner tube method works well on standard motors as long as your jubilee clip seals well

[Storkfoot]

Thanks, Paul. Another friend has just kindly pointed out that a 30mm Dell’orto rubber manifold will seal on a 28mm OD inlet manifold with a decent jubilee clip.

[lofty]

i used a rubber bung off ebay, the type used to seal bottles and test tubes in labs and food factories..
various sizes available..

[Toddy]

i used a rubber bung off ebay, the type used to seal bottles and test tubes in labs and food factories..
various sizes available..

Any links buddy save me searching

[lofty]

here is an example (there are plenty of similar on ebay)

i suggest no holes (you can always drill one if you want to attach the pump/gauge)
measure the inside diameter of your manifold(s) and pick a bung with the small diameter a bit less, and the big diameter a bit more.. hopefully it can fit a number of manifolds (say 18/20/22).

you can also get a bigger one for the exhaust if you have a stub or U bend with a round hole to plug.

https://www.ebay.co.uk/itm/143373695266?_trkparms=ispr%3D1&hash=item2161bcf922:g:0hwAAOSwSGFdb8uM&amdata=enc%3AAQAGAAACgPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsS9d9gBrkNbRQtRn8MVXnYkispudzDHHKd6PmWJSLLBUtLcuSDbfl1mNt84cegt6NGnXhX99Sq3wyNAo2kvQnRrH4Ky3MD%252FEJoGJSQpCpGEs24IEy%252BjIl99ruLXo69jV3tEQeQnePt0NrIfRBesfOkwPCM1k1aGfGZQWv2lgGdnREhYI01rP0t1sdvNMmq0XjGFTMsbPcATAd9mEyoM%252Bj3ZQ9uwmPxm27%252FVPx2CgHe6cOekNhUwZsVCRkQgm4JapQt6zf48t125YFvll1A9BZz1GAx6%252B2NxiuWAp1%252BYRxGjK3UgtbBQ0SwhRs5u8M%252FbhGC27OyQTmGHjXSCDNWhiR5uDtjaBgUJVOKn7%252B%252BuBraWvYsKSAmzS0O0tewXB1rC4w%252Fft16gy%252BLgPCVtl0HRBWpVCLv%252BvxW5TUBoaC1uAVpeiZleN8PTsndap%252Fnw0ey9xlChtuwLyaYJ4eN7EweiodQNsTNw8noZvX7BOnTS%252B6TwSrSjUSkx40xH7Ru3Ho2dIYW2D%252F6BLpG%252FTo9afqDYjD5oQ4SLyvd1yZKw%252BR3Gyg4EejkZ7VnkpXr3b3GGO8Sl2XOc%252Bv43O17l%252Bi1%252Bt3qqE9gKAgbx3hPGaR5Q6veM5PjiMkOMDJUL7RlghDX6ZcSK6y1z6WvsaTn%252F3WunEeZATbEmwcflZPyZ8MMtKrWxdEFEb1YI2CoctW%252FbM68vgIuWbIWmTjpEnuTjSgDrzIueO5BL6FQQkbTFmWHC%252FywRQO6MTap06vO7v%252F6rtx4rawPaRuVVCTp4hSh9fBNR7c%252FcWCJe01j%252Fb6EAcB5RVr2LcL37ZY%253D%7Campid%3APL_CLK%7Cclp%3A2334524

while i am at it, if you want to plug a rubber mounted carb manifold (with rubber attached) you can get the appropriate size one of these ear 'ole stretchers and hold it in with a jubilee clip, works quite well..

https://www.ebay.co.uk/itm/142980068608?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D233037%26meid%3Dabb44c2fc1e84506a12539405c43b632%26pid%3D101195%26rk%3D2%26rkt%3D12%26sd%3D141898944628%26itm%3D142980068608%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv9PairwiseUnbiasedWeb%26brand%3DUnbranded&_trksid=p2047675.c101195.m1851&amdata=cksum%3A142980068608abb44c2fc1e84506a12539405c43b632%7Cenc%3AAQAGAAACENwvczSw05WMu8UOFZKhRUwVKVOavkDtG2k5uFBgfUZ4UY%252BGkAn4G0bGzi41aMHHHko%252BfKx6YRtQ%252FtoBmt004ilxRBTJxhUYwZ%252BdWg8o4NqLzm5y9x%252FbEDLfumq9S55RqoM4XaiuiGGElvqz0lCVHwN6hoNamSExDGP7wp8Pk4V2fnO7p0osij%252FCxIP2BsRWh4%252B%252BHORSmA2fa0i6fqspVyELMQ%252Fhnjf88RO6Q9Cv1SzBqb5DLQbVb%252BN1DXATfDUDXwJrUaTjVilPTwrPJe6l8afq8j1IyBPBXcLRNQPARayX4E5o8GcqKju97g%252FNvTO6wyBxgUgLKxE81DxMGCYKM2aUco5mYEli3OdEpYKS3DveiEOptxRsqnMPbMiEkoEW7ZwMYJAfQ2lc5xOBNe1iQ2FL%252FBqJLF%252FsGDmFPk%252F4Bd7lsOLp7l1aAyvAEs4y991dBPwTxc92IAQyq%252F2O7bVAiXfrQqpthMCL9NYIinRcpBFldTXrEtDE2kHYMqwj7CaseGS%252Bf776iek%252FiVmYs2UVGY%252B9YQIy7j0uZ9B5vBotynILFQTdkqYeymM7feA38z3ZGDuMYhad92E4BGIARMl%252B%252FyGIaYZMQZVIR2eAiESwEsoPAFB9Beuzi9LhBgcREccbXRNPDn6KOGvWLEMtB%252Bl470gerZnDhUzaOiaoY1oJxdsntjqZyctYchFTW4%252FOPvrREg%253D%253D%7Campid%3APL_CLK%7Cclp%3A2047675

[Toddy]

here is an example (there are plenty of similar on ebay)

i suggest no holes (you can always drill one if you want to attach the pump/gauge)
measure the inside diameter of your manifold(s) and pick a bung with the small diameter a bit less, and the big diameter a bit more.. hopefully it can fit a number of manifolds (say 18/20/22).

you can also get a bigger one for the exhaust if you have a stub or U bend with a round hole to plug.

https://www.ebay.co.uk/itm/143373695266?_trkparms=ispr%3D1&hash=item2161bcf922:g:0hwAAOSwSGFdb8uM&amdata=enc%3AAQAGAAACgPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsS9d9gBrkNbRQtRn8MVXnYkispudzDHHKd6PmWJSLLBUtLcuSDbfl1mNt84cegt6NGnXhX99Sq3wyNAo2kvQnRrH4Ky3MD%252FEJoGJSQpCpGEs24IEy%252BjIl99ruLXo69jV3tEQeQnePt0NrIfRBesfOkwPCM1k1aGfGZQWv2lgGdnREhYI01rP0t1sdvNMmq0XjGFTMsbPcATAd9mEyoM%252Bj3ZQ9uwmPxm27%252FVPx2CgHe6cOekNhUwZsVCRkQgm4JapQt6zf48t125YFvll1A9BZz1GAx6%252B2NxiuWAp1%252BYRxGjK3UgtbBQ0SwhRs5u8M%252FbhGC27OyQTmGHjXSCDNWhiR5uDtjaBgUJVOKn7%252B%252BuBraWvYsKSAmzS0O0tewXB1rC4w%252Fft16gy%252BLgPCVtl0HRBWpVCLv%252BvxW5TUBoaC1uAVpeiZleN8PTsndap%252Fnw0ey9xlChtuwLyaYJ4eN7EweiodQNsTNw8noZvX7BOnTS%252B6TwSrSjUSkx40xH7Ru3Ho2dIYW2D%252F6BLpG%252FTo9afqDYjD5oQ4SLyvd1yZKw%252BR3Gyg4EejkZ7VnkpXr3b3GGO8Sl2XOc%252Bv43O17l%252Bi1%252Bt3qqE9gKAgbx3hPGaR5Q6veM5PjiMkOMDJUL7RlghDX6ZcSK6y1z6WvsaTn%252F3WunEeZATbEmwcflZPyZ8MMtKrWxdEFEb1YI2CoctW%252FbM68vgIuWbIWmTjpEnuTjSgDrzIueO5BL6FQQkbTFmWHC%252FywRQO6MTap06vO7v%252F6rtx4rawPaRuVVCTp4hSh9fBNR7c%252FcWCJe01j%252Fb6EAcB5RVr2LcL37ZY%253D%7Campid%3APL_CLK%7Cclp%3A2334524

while i am at it, if you want to plug a rubber mounted carb manifold (with rubber attached) you can get the appropriate size one of these ear 'ole stretchers and hold it in with a jubilee clip, works quite well..

https://www.ebay.co.uk/itm/142980068608?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D233037%26meid%3Dabb44c2fc1e84506a12539405c43b632%26pid%3D101195%26rk%3D2%26rkt%3D12%26sd%3D141898944628%26itm%3D142980068608%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv9PairwiseUnbiasedWeb%26brand%3DUnbranded&_trksid=p2047675.c101195.m1851&amdata=cksum%3A142980068608abb44c2fc1e84506a12539405c43b632%7Cenc%3AAQAGAAACENwvczSw05WMu8UOFZKhRUwVKVOavkDtG2k5uFBgfUZ4UY%252BGkAn4G0bGzi41aMHHHko%252BfKx6YRtQ%252FtoBmt004ilxRBTJxhUYwZ%252BdWg8o4NqLzm5y9x%252FbEDLfumq9S55RqoM4XaiuiGGElvqz0lCVHwN6hoNamSExDGP7wp8Pk4V2fnO7p0osij%252FCxIP2BsRWh4%252B%252BHORSmA2fa0i6fqspVyELMQ%252Fhnjf88RO6Q9Cv1SzBqb5DLQbVb%252BN1DXATfDUDXwJrUaTjVilPTwrPJe6l8afq8j1IyBPBXcLRNQPARayX4E5o8GcqKju97g%252FNvTO6wyBxgUgLKxE81DxMGCYKM2aUco5mYEli3OdEpYKS3DveiEOptxRsqnMPbMiEkoEW7ZwMYJAfQ2lc5xOBNe1iQ2FL%252FBqJLF%252FsGDmFPk%252F4Bd7lsOLp7l1aAyvAEs4y991dBPwTxc92IAQyq%252F2O7bVAiXfrQqpthMCL9NYIinRcpBFldTXrEtDE2kHYMqwj7CaseGS%252Bf776iek%252FiVmYs2UVGY%252B9YQIy7j0uZ9B5vBotynILFQTdkqYeymM7feA38z3ZGDuMYhad92E4BGIARMl%252B%252FyGIaYZMQZVIR2eAiESwEsoPAFB9Beuzi9LhBgcREccbXRNPDn6KOGvWLEMtB%252Bl470gerZnDhUzaOiaoY1oJxdsntjqZyctYchFTW4%252FOPvrREg%253D%253D%7Campid%3APL_CLK%7Cclp%3A2047675

Cheers lofty