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Sounds interesting.
Cylinder at TDC on a compression stroke. There should be maybe a small amount seeping past the rings for an older engine. (nothing to extreme..just a whisper) As for the oil cap and intake?
Are you sure you did the test correctly?
What are the symptoms you have? Compression test results? etc…. Need some input to understand the issues at play here.
S-
I’m wondering why you’re doing leak down testing to start with and have you followed up with a simple vacuum test at idle? If you’ve got a fluctuating needle on vacuum testing, it could support the potential for a valve or seat problem. A running compression test might be a good follow up test too. It can be a good measure of engine breathing. Is the behavior of the leak down test the same for all the cylinders? Reason I’m asking is I’m wondering if cam timing off by a tooth would be enough to allow just a little leakage with your scenario.
This is very interesting. Please keep us posted as you learn stuff.
The engine is running good just was checking the condition of it and i did the leak down test right with the cylinder at TDC on the compression stroke and all cylinders had about 10% leakage. compression on all cylinders is 195.. just notice when i did the leak down test and took the oil cap off the air would stop flowing through intake and it would just leak through oil fill
This should have been easy from the get go and now I’m embarassed. When you leave the cap on, you’re eventually going to fill the crank case with that 10% leakage. That leakage needs a way out and it finds that way through the pcv valve that’s invariably connected to your intake manifold.
[quote=”no_common_sense” post=113692]This should have been easy from the get go and now I’m embarassed. When you leave the cap on, you’re eventually going to fill the crank case with that 10% leakage. That leakage needs a way out and it finds that way through the pcv valve that’s invariably connected to your intake manifold.[/quote]
+1 sounds like the most reasonable explanation to me. I would also add that when you put the cap back on you take away your ability to hear the leakage which can also contribute.
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