What the hell?
Thread Starter
Heel & Toe
Joined: Dec 2008
Posts: 18
Likes: 0
From: Altus OK
What the hell?
I changed the valve springs in my car. I used the compressed air method of keeping the valves closed. When I got done I decided to do a compression check because I had never done one. All cylinders checked good at around 170 psi except #3 which is reading 0 psi yeah!! none, zip, zilch, nothin. So I hooked the air compressor back up to that cylinder and now the air just whistles right through it. This wasn't the case when I changed the springs. So what did I not put back on correctly?
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I assume that you have already adjusted the valve lash. Chances are that you have either the intake or exhaust TOO TIGHT. Re-adjust the valves for this cylinder and re-test.
PS---most compressors only put out 120 psi which should not have any impact on the rings.
PS---most compressors only put out 120 psi which should not have any impact on the rings.
Last edited by John A. Marker; Mar 18, 2010 at 11:23 PM.
Advanced
Joined: Dec 2007
Posts: 52
Likes: 0
From: Waynesville Ohio
I don't think 87s are adjustable valve lash...mine wasn't....maybe you twisted swivled the valve and now it's not seating. where's the whistling coming from? feel it from the intake or exhaust ports (valve) or not (trouble). I doubt you could have popped a ring on compressor pressure (think about it others are testing at 175psi...are you running that on your compressor).
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
How many turns did you set the lash to? I never go more than a full turn. But yeah, I'd back off the rocker nuts and see if pressure holds. If it does then you know you went too tight.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 765
if the "air just whistles", sounds like you have an open valve. go back and check the assembly of the spring, retainer, locks, etc. then check the valve/lifter adjustment. it just may be too tight, and the intake or exhaust valve is not fully closing. readjust the valves.
i never did like the "spin the pushrod until resistance is felt" method of adjusting valves. i set "zero" lash by inserting a .0015 feeler gauge between the valve stem and the rocker arm, and turn the nut until the feeler gauge grabs, at that point, turn the adjusting nut another 3/4 turn. i feel this gives a more precise, even, across the board, adjustment of the valves.
i never did like the "spin the pushrod until resistance is felt" method of adjusting valves. i set "zero" lash by inserting a .0015 feeler gauge between the valve stem and the rocker arm, and turn the nut until the feeler gauge grabs, at that point, turn the adjusting nut another 3/4 turn. i feel this gives a more precise, even, across the board, adjustment of the valves.
Last edited by Joe C; Mar 19, 2010 at 04:25 AM.
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Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi
Thread Starter
Heel & Toe
Joined: Dec 2008
Posts: 18
Likes: 0
From: Altus OK
It was the valve adjustment. Backed them off and readjusted. Compression is good now 170psi like the rest. Maybe its in my head its been a long time since I drove the car and it feels sluggish now.
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
What did you set the preload at? I use 1/2 turn past zero lash. Works pretty good for me. The reason I ask is if you got that one to tight you may have got the rest or some of the rest to tight. It can make a difference if to tight. Better to have them a little on the loose side.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
The only thing new valve springs will cure is valve float and valve bounce. The springs won't affect how an engine runs unless they are too high of tension for your application.
Too tight of valve lash will bleed off some compression once an engine warms up.
I'd redo the valve lash, and not get so close to the limit next time.
Too tight of valve lash will bleed off some compression once an engine warms up.
I'd redo the valve lash, and not get so close to the limit next time.