valve spring question

  #1  
Old 01-16-2013, 11:18 PM
thebandit110's Avatar
2nd Gear member
Thread Starter
Join Date: Jan 2007
Posts: 403
Default 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
 
  #2  
Old 01-16-2013, 11:53 PM
BasicConcepts's Avatar
Overdrive Member
Technical User
Join Date: Oct 2009
Location: Greenville, South Carolina
Posts: 4,597
Default

you have a leak somewhere, either the rings, a leaky valve or your hose is leaking.
 
  #3  
Old 01-17-2013, 09:38 AM
Camaro 69's Avatar
Senior Moderator
January 2010 ROTM Winner
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
Default

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.
 

Last edited by Camaro 69; 01-17-2013 at 09:40 AM.
  #4  
Old 01-17-2013, 06:34 PM
thebandit110's Avatar
2nd Gear member
Thread Starter
Join Date: Jan 2007
Posts: 403
Default

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  
Old 01-17-2013, 06:39 PM
thebandit110's Avatar
2nd Gear member
Thread Starter
Join Date: Jan 2007
Posts: 403
Default

I actually think its okay. I didnt hear anything coming out of the tail pipe, or the intake port. Thats my youtube page. Be sure to watch the video of my 1980 Z-28 my students and I are working on at my job! Thanks guys!
 
  #6  
Old 01-18-2013, 12:35 AM
Camaro 69's Avatar
Senior Moderator
January 2010 ROTM Winner
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
Default

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.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
94z28chevy
93-02 Transmission & Differential
0
08-04-2011 11:23 PM
doww301
93-02 General
5
10-20-2010 11:24 AM
Slick6
93-02 General
1
07-05-2008 10:59 PM
sewerrat
Engine & Internal
1
03-27-2008 02:13 AM


Thread Tools
Search this Thread
Quick Reply: valve spring question



All times are GMT -5. The time now is 07:52 AM.