True Leakdown Tester - Recommendations?

[SteveSr]

Hello,

I am looking for a true leakdown tester for use on small engines. This is the type to test valve leakage and and ring sealing in 4-strokes. Primary use will probably be on Stihl 4-mix but could also find use on other small engines.

Thanks,

 

[heimannm]

Mark

 

[SteveSr]

View attachment 309719

Mark

Any idea who makes this for Stihl?

 

[Vintage Engine Repairs]

I made my own after being let down by two expensive pieces of rubbish. Do a quick YouTube search, it’s so simple..

 

[SteveSr]

I made my own after being let down by two expensive pieces of rubbish. Do a quick YouTube search, it’s so simple..

Yes, a regulator, 2-calibrated gauges separated by a calibrated orifice. It is interesting that Stihl removes the inlet side pressure numbers from their gauge so that you don't really know what pressure you are testing at. I am also wondering if they have changed the "standard" .040" diameter orifice to something smaller to better fit with small engine usage.

 

[Vintage Engine Repairs]

Yes, a regulator, 2-calibrated gauges separated by a calibrated orifice. It is interesting that Stihl removes the inlet side pressure numbers from their gauge so that you don't really know what pressure you are testing at. I am also wondering if they have changed the "standard" .040" diameter orifice to something smaller to better fit with small engine usage.

I highly doubt they’d adjust the orifice size, it’s very much an industry spec. The hole is 1mm so it’s really not much. I think they’d explain in the instructions to open the regulator on the left gauge to “position 1” (furthest to the right) and then just note the percentage loss off the right gauge to keep it simple.

I do like it, being Stihl and all! Hahah

here is mine:

 

[SteveSr]

So where did you find the calibrated 1mm orifice or did you make it? Also, how do you read the leak % from the psi gauge?

I did find out that the Stihl tester (5910-850-0300) is made by Thexton. I looked in their catalog but didn't see anything similar so it must be a private contract. There is also some more information on it contained in Stihl training documentation TLS 205. If anyone has access to this I would appreciate a PM.

 

[Vintage Engine Repairs]

Just made it, fill that tube with Jb weld, let it cure and drill the hole out.

to read the leak down there is an equation, When in back in the workshop I’ll photograph the document I made as a reminder and share it here.

 

[SteveSr]

Here is a thread from the guy that developed the Stihl tester:

https://www.masterblasterhome.com/threads/leak-down-gauge-search.23384/

It sounds like they modified their version to test at lower pressures to avoid blowing out crankcase seals if used on sealed engines. They may have also done "something" to increase the sensitivity. It would be nice to know what those gauges really read in PSI.

 

[Stevetheboatguy]

Here is a thread from the guy that developed the Stihl tester:

https://www.masterblasterhome.com/threads/leak-down-gauge-search.23384/

It sounds like they modified their version to test at lower pressures to avoid blowing out crankcase seals if used on sealed engines. They may have also done "something" to increase the sensitivity. It would be nice to know what those gauges really read in PSI.

My guess would be they are 0-50 gauges with the psi markings removed. The pic from Mark is fuzzy but it looks to have a 0-50 regulator. So 0-50 gauges makes the most sense to me.


Steven

 

[Vintage Engine Repairs]

Interesting, with a simple equation you can test at whatever psi you wish… here is a video I did…