Engine Valve Springs
Thread Starter
Melting Slicks
Joined: Sep 2000
Posts: 2,403
Likes: 416
From: Chester Virginia
Engine Valve Springs
Last month one the valve spring broke on me on the way home from work, just at the entrance to my driveway. I have just finished replacing all the springs and installing umbrella oil seals. Before I start it up any thoughts on what to check/do/double check, etc.?
I plan on an oil change after the start-up.
I did a leakdown test on each cylinder as I replaced the springs. Highest leakage was 17% with a cold engine that had not been started in three weeks. The springs had over 100,000 miles on them at the failure and when the engine was 'rebuild' at 98,000 .060" shims were put under the springs.
Roger
I plan on an oil change after the start-up.
I did a leakdown test on each cylinder as I replaced the springs. Highest leakage was 17% with a cold engine that had not been started in three weeks. The springs had over 100,000 miles on them at the failure and when the engine was 'rebuild' at 98,000 .060" shims were put under the springs.
Roger
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
If the springs are set at the correct height, resulting in the correct open and closed pressures for the camshaft, make sure you are .100 or more away from the solid stack height. If you are at or near coil bind, they will break. Springs are funny. Every once in a while, all will be set perfect, and one will break. Not often, but rarely. I pulled my hair out for days once trying to find a problem that didn't exist. Sometimes they just break. Most times though, there is a solid reason. Coil bind being the biggie.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Springs fatigue out and can fail from age over time. I believe this is the most common failure cause, not being set up to go solid.
It is also possible for the springs to resonate during valve float which can severely reduce the life and/or force the springs provide.
It is also possible for the springs to resonate during valve float which can severely reduce the life and/or force the springs provide.
