valve spring question
#1
valve spring question
Okay. So Im putting new valve springs on my car. Never have done it before. When I blow the cylinder up with air, Is it normal to hear air escaping the cylinder? I have the oil pan off and it sounds like it is coming from there. I checked multiple cylinders and I hear it. I was just curious ? Thanks
#3
Is it normal to have air escaping, yes since neither the rings nor valves seal completely air tight. But how much is the question. If what you're hearing from the crankcase is like a wind tunnel, then you have worn rings.
You really want to give the engine a leak down test. Buy, rent, or make a leak down tester tool. It consists of an air hose coupler, a regulator, a T with an air gauge, another air coupler, and a flex hose with a spark plug adapter (with appropriate fittings to put it all together).
Set the regulator on your air compressor to be above 100 psi (110-120). With the piston at TDC, screw the flex hose into the plug hole. Hook your air compressor hose up to the "test tool" and turn the regulator **** on it till the gauge reads 100 psi. Hook the flex hose to the tool and watch the gauge. Anywhere up to 10% loss (90 psi) is still considered very good. 15% is so-so, 20% is pushing it, and above that just ain't good. Also, give a listen to your tail pipe and intake (crack open the butterflies). If you hear air there too, it means your valves are leaking.
If you need to, check youtube for some leak down how-to's. I'm sure there are some good tutorials there.
You really want to give the engine a leak down test. Buy, rent, or make a leak down tester tool. It consists of an air hose coupler, a regulator, a T with an air gauge, another air coupler, and a flex hose with a spark plug adapter (with appropriate fittings to put it all together).
Set the regulator on your air compressor to be above 100 psi (110-120). With the piston at TDC, screw the flex hose into the plug hole. Hook your air compressor hose up to the "test tool" and turn the regulator **** on it till the gauge reads 100 psi. Hook the flex hose to the tool and watch the gauge. Anywhere up to 10% loss (90 psi) is still considered very good. 15% is so-so, 20% is pushing it, and above that just ain't good. Also, give a listen to your tail pipe and intake (crack open the butterflies). If you hear air there too, it means your valves are leaking.
If you need to, check youtube for some leak down how-to's. I'm sure there are some good tutorials there.
Last edited by Camaro 69; 01-17-2013 at 09:40 AM.
#4
Well I was just unsure how much was to much. I ran a compression test when I got the car and all cylinders had great compression and all within a pound or two of each other, Nothing to be concerned about. But when I hooked it to the air to do springs I heard air escaping. I actually took a video with my Iphone and I am going to post it next. Im also going to try and figure out how much PSI I am losing. Thanks for the input Camaro69.
#5
#6
When doing a leak down test, the engine wants to be at or near normal running temperature. You're likely to get more ring blow-by when the engine is cold, as yours is. You can always go back and pump air in the cylinder again once you get the engine running. Although with the pan on, you won't be able to hear air rushing the same as you can now.
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