Nice video, but I was always told as an ape 55 years ago was to have the butterfly wide open so maximum air can enter the cylinders while cranking 👍 as for the leak down test I’ve just bought one because on checking my compression on one of my cars a 1938 that seamed to run ok I did a compression test on all 4 and much to my surprise number 3 was only 35 psi 😱😱😱 so I’m going to look further into it obviously 😢. I like your channel and straight forward work 😀😀
If you don't open the throttle, it just takes longer, more cranking, to reach max pressure. Max pressure isn't the point of the test. We test to see how healthy each cyl is compared to the rest. Thanks for watching and good luck with your project.
Nice to see how a leak down works. I don't quite understand how it builds such good compression on 4 when it's also leaking 15% more than no. 1. Also on 998 high compression I see numbers nearer 190. You don't mention wide open throttle for the compression test, is that just something people say? Lastly do you know why you can still see good compression with a blown head gasket cylinder to water gallery? Sorry for all the different points in one!
I'm at 6000ft of elevation. The compression numbers are lower up here due to less available air. The two tests check different things. A cyl with good compression can have bad leakdown. The rapid rise of the piston can help seal the rings up. Also compression is a peak measurement.
Also I did have the throttle held open for the test. Just forgot to mention it. Blown gasket to water has back pressure of the water to help contain the cyl pressure. Leakdown would show that cyl as bad.
Great video thanks. Ive seen ACDodd doing Leakdown testing while reworking a head on the bench, but this is the first time ive seen testing on a full engine. So thank you. Whats the likelihood of the rings playing a large roll in this?
Darren it didnt look like the gauge was zeroed when you were leakdown testing cylinders 3,4,2 - are you sure theyre much worse that #1? Thanks for all the content!
Good spotting! Normally i dont have to worry about rezeroing the gauge when I do the test but I had the power turned off to the compressor while filming and the pressure to the gauge dropped off a bit. I think it was off by 10 psi by the last cyl. Therefore all the cylinders were about the same 10-15 % leakdown. A better example is coming out on Friday with a good motor getting leakdown tested.
Nice video, but I was always told as an ape 55 years ago was to have the butterfly wide open so maximum air can enter the cylinders while cranking 👍 as for the leak down test I’ve just bought one because on checking my compression on one of my cars a 1938 that seamed to run ok I did a compression test on all 4 and much to my surprise number 3 was only 35 psi 😱😱😱 so I’m going to look further into it obviously 😢. I like your channel and straight forward work 😀😀
If you don't open the throttle, it just takes longer, more cranking, to reach max pressure. Max pressure isn't the point of the test. We test to see how healthy each cyl is compared to the rest. Thanks for watching and good luck with your project.
Thanks for another excellent video Darren.
Thanks for watching
Clear, concise and very helpful, thanks Darren.
Thanks for the feedback
Thank you!
You're welcome! Thanks for watching
Nice to see how a leak down works. I don't quite understand how it builds such good compression on 4 when it's also leaking 15% more than no. 1. Also on 998 high compression I see numbers nearer 190. You don't mention wide open throttle for the compression test, is that just something people say? Lastly do you know why you can still see good compression with a blown head gasket cylinder to water gallery? Sorry for all the different points in one!
I'm at 6000ft of elevation. The compression numbers are lower up here due to less available air.
The two tests check different things. A cyl with good compression can have bad leakdown. The rapid rise of the piston can help seal the rings up. Also compression is a peak measurement.
Also I did have the throttle held open for the test. Just forgot to mention it.
Blown gasket to water has back pressure of the water to help contain the cyl pressure. Leakdown would show that cyl as bad.
@@darrensrestorations991 thanks for the explanations mate, all good stuff 👍
Great video thanks. Ive seen ACDodd doing Leakdown testing while reworking a head on the bench, but this is the first time ive seen testing on a full engine. So thank you. Whats the likelihood of the rings playing a large roll in this?
This motor mostly had valve leakage. I could hear the air leaking into the intake and exhaust. I'm sure some was leaking past the rings as well.
Darren it didnt look like the gauge was zeroed when you were leakdown testing cylinders 3,4,2 - are you sure theyre much worse that #1?
Thanks for all the content!
Good spotting! Normally i dont have to worry about rezeroing the gauge when I do the test but I had the power turned off to the compressor while filming and the pressure to the gauge dropped off a bit. I think it was off by 10 psi by the last cyl. Therefore all the cylinders were about the same 10-15 % leakdown.
A better example is coming out on Friday with a good motor getting leakdown tested.
how much pressure coming from your compressor for the leak down test?
The actual compressor pressure doesn't matter. The knob on the tester is used to match whatever pressure you have.