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My 2012 service manual calls for a warm engine and 10% maximum leak down. I’m curious to hear opinions from people with more experience doing leak down testing on many engines. It’s interesting that the twin cams call for 10% or less and the M8’s are up to 25%. Here’s another thing I’d be interested to hear what experienced mechanics would have to say about this.
My primary is disassembled waiting for parts. I plan on leak down testing my engine both warm and cold to see the difference. It’s a 2012 twin cam that’s been bored to a 107.
Like many other companies, HD is loosening their QC. By doing so, they'll save some money in warranty repairs. They are known to have problems with cylinders bored out of round, and instead of fixing the cause of the problem, this is the path they chose.
Like many other companies, HD is loosening their QC. By doing so, they'll save some money in warranty repairs. They are known to have problems with cylinders bored out of round, and instead of fixing the cause of the problem, this is the path they chose.
Just like when they bumped up the allowable runout of the twin cam a few times until it reached 0.012" allowable runout around 2012ish.... All about money.... $$$$$
Pre-Evo I could understand a worn engine nearing 25%. Harley did have a problem keeping cylinders "round." With modern machining techniques, and today's metallurgy, there is no excuse for 25% leakage. I cannot believe that they meet emissions with numbers like that. Oil burning is a huge hit on exhaust contaminants. Combustion byproducts raise hell on the engine oil too, and mixed with moisture create acid that etches journal surfaces.
I do it cold when I'm looking for other issues with an engine, actuall cylinder sealing performance at operating temp and repeat 3 times then average the numbers, it will fluctuate.
I've seen significant differences from cold to hot and then I've seen smaller variations. The leakdown test is just one data point that should be used in concert with other diagnostic tools when troubleshooting or making condition evaluations. I find the biggest values are as a baseline reading on a new engine and when performing a condition assessment it can instantly indicate where the leakage is at. If you're also performing a compression test, don't forget to adjust for density altitude at the time of the test.
I've seen significant differences from cold to hot and then I've seen smaller variations. The leakdown test is just one data point that should be used in concert with other diagnostic tools when troubleshooting or making condition evaluations. I find the biggest values are as a baseline reading on a new engine and when performing a condition assessment it can instantly indicate where the leakage is at. If you're also performing a compression test, don't forget to adjust for density altitude at the time of the test.
If you're also performing a compression test, don't forget to adjust for density altitude at the time of the test.
Sorry - I don't understand this. Can you explain a little bit further? Are you talking about the air pressure in the environment in which you're doing the test? For example in the mountains or at the sea?
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