Been browsing compression & leakdown testers with a view to possibly investigating my ill ZX - does anyone know if a small 12v compressor could supply the volume of air (eg http://www.toolsbypost.com/product.php? ... 37f63adb9c)
For a 1.4 cylinder @ TDC this must be circa 100cc or way less? as each cylinder is only 340cc.
From reading up about this, it's the pressure required - 100psi+ rather than any great volume of air.
Anyone got experience of leakdown testing?
Cheers
Jonathan
Leakdown test
Moderator: RichardW
Leakdown test
If Stupidity got us into this mess, then why can’t it get us out?
51 Clio 1.2, 01 Avensis
51 Clio 1.2, 01 Avensis
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simoncanfer
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One way of getting this kind of information is to use a computer-based data logger on the starter motor current - more current = more power required to turn over the engine = higher compression.
See http://www.picoauto.com/waveforms/Charg ... ave51.html
These scopes are really useful for modern auto electrics, they give you a better understanding of what's going on than many garages with their error code readers in my opinion!
See http://www.picoauto.com/waveforms/Charg ... ave51.html
These scopes are really useful for modern auto electrics, they give you a better understanding of what's going on than many garages with their error code readers in my opinion!
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handyman
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Hello Usererror, I think you will find a 12V compressor will struggle to maintain 100psi! I have just read your link to this bit of Sealey rubbish. The gauge reads to 240psi, but the compressor only delivers 30psi. Most car tyres are inflated above 30psi, so I assume this compressor is used to inflate the airbed when you go camping!
I have a number of different gauges for testing compression, leaking valves, cylinder/ring blow by, etc. I used to use blowdown or leakdown tests regularly on rally and racing engines and providing you can isolate each cylinder, the readings on the gauges will tell you alot about that cylinder's internal condition. That is the real clue, interpreting the readings.
I would think the easiest gauge you could use would be a standard compression tester as that will tell you the most relevant information and I do not think they are expensive nowadays.
As for using a scope to interpret cylinder condition, the feedback from the starter is so limited, it will not give you all the conditions likely to affect engine performance. Cranking speeds and voltages are subject to many other variables within the vehicles electrical system. I am not dismissing this system, but it is not a substitute for a leakdown test.
Handyman
I have a number of different gauges for testing compression, leaking valves, cylinder/ring blow by, etc. I used to use blowdown or leakdown tests regularly on rally and racing engines and providing you can isolate each cylinder, the readings on the gauges will tell you alot about that cylinder's internal condition. That is the real clue, interpreting the readings.
I would think the easiest gauge you could use would be a standard compression tester as that will tell you the most relevant information and I do not think they are expensive nowadays.
As for using a scope to interpret cylinder condition, the feedback from the starter is so limited, it will not give you all the conditions likely to affect engine performance. Cranking speeds and voltages are subject to many other variables within the vehicles electrical system. I am not dismissing this system, but it is not a substitute for a leakdown test.
Handyman