Broken valve spring

[shadango]

Hi all

While driving today, the motor in my fish started missing.....backfired a few times then misses.......tracked it down to a dead cylinder 3......pulled the valve cover and found a broken (in two places) valve spring on the exhaust valve, cylinder 3.

I think these are aftermarket/performance springs as they have an inner spring to them as well as the outer red one.....picture below....I know I have a purple cam (no idea on the specs), and these are J heads....318 motor.....

Do springs usually have a marking or something so I can get just one spring maybe?  Or should I replace them all?

I do have the tools needed so I do not have to pull the heads.... -- a fitting to air up the cylinder and a clamp like device for compressing the spring.....my fatherinlaw used to do this stuff all the time and he gave me his tools.....(thanks Dad!)

I have the rockers off and am waiting to pull that spring until he can come over and keep an eye on me.   LOL

First wide shot photo is just showing the springs in general.....the second is the broken one.





Any thoughts?

[cudabob496]

I'd do a thorough investigation of your entire valve train, making sure all
geometry is correct, or this may be the tip of the iceberg. check lifters
pushrods, rockers, spring heights, spring strength, retainers, etc.

[jimynick]

What the man said! Be happy that they're double springs, because if they'd been singles, you could have dropped that valve into the cylinder and THEN you'd have a miss. As for replacing them all or one, I think it'd be a false economy to roll the dice again by changing just the one. My thinking goes along the " if one failed, how far ahead is the next one" road. Be SURE to check the coil bind distances at full lift, the old rule of thumb used to be .100", but you can get by with a bit less as it's not a race engine. Be sure to check the retainer bottom to head valve guide boss clearance as well. When you've got the air on, see if the valve seals up correctly and rotates concentrically and I'd do a quick compression test on that bank to make sure everything there was kosher. But then, that's just my 

[72cudamaan]

Those look like original single springs. Someone painted them red so they would look pretty. The inner is a dampner
that has no strength to it. It's function is to keep the outer spring from chattering. Without knowing what cam you have it's hard to tell
if the springs are strong enough. But as said, you should replace them all. Also change those aluminum retainers. Those
things are scary. If you can give me the specs to one of your "good" springs I may have what you need. Look for a pm

[shadango]

I'd do a thorough investigation of your entire valve train, making sure all
geometry is correct, or this may be the tip of the iceberg. check lifters
pushrods, rockers, spring heights, spring strength, retainers, etc.

Not sure if it helps, but I have put some decent mileage on the motor.    I would say about 10-15k miles on it since I got it.  And it was supposed to have had 5k or so on it when I got it.

[cudabob496]

Not sure if it helps, but I have put some decent mileage on the motor.    I would say about 10-15k miles on it since I got it.  And it was supposed to have had 5k or so on it when I got it.

thats not really a lot of mileage, and the fact that the spring failed so soon is an indicator
of a potentially serious problem.  Of course, a spring might also break if its getting no oil for cooling.
But as mentioned above, you are fortunate that there was not worse damage.  I'm not a valve train expert,
but there are many things to check and measure to make sure you are safe to go again.

Interesting the the spring broke at the base.  That might give a clue as to why it happened.

[shadango]

Be SURE to check the coil bind distances at full lift, the old rule of thumb used to be .100"

Excuse my ignorance.......all new to me.....So that is the distance between coils when the valve is completely open or when it is being compressed open?

Be sure to check the retainer bottom to head valve guide boss clearance as well.

So just making sure there is clearance around the spring where it seats , yes?   I can say that the broken spring rotates around really easily (all of the spring parts, not just half, etc)

When you've got the air on, see if the valve seals up correctly and rotates concentrically and I'd do a quick compression test on that bank to make sure everything there was kosher. But then, that's just my 

I did a compression check on all cylinders.....all around what they were when I did the last couple checks over the years as I recall...I had posted the results here on the forum, gonna see if I can find those numbers.......


This reading --

cyl       reading

1           133
 2          127
3            dead
4            140
5            138
6             141
7            130
8            144

[shadango]

thats not really a lot of mileage, and the fact that the spring failed so soon is an indicator
of a potentially serious problem.  Of course, a spring might also break if its getting no oil for cooling.
But as mentioned above, you are fortunate that there was not worse damage.  I'm not a valve train expert,
but there are many things to check and measure to make sure you are safe to go again.

Interesting the the spring broke at the base.  That might give a clue as to why it happened.

I ran the motor for a short time and I also cranked her over with the cover off and watched the springs on that side.....none of them looked to be "binding" if bonding means bottoming out or deflecting funny....all looked fine except for the broken one of course.

Before the all happened, I did rev her a few times but drive the car for a few miles afterwards with no problems.  The, I was sitting at a red light on a slight down hill and when I started back out on the road again in 1st she started missing..........

[Strawdawg]

Replace all the springs.  Check the new install.   It's not all that uncommon to break one... Particularly if they are no name specials

Steve

[cudabob496]

 
https://www.youtube.com/watch?v=5GBNLlsivNs

http://www.digitalcorvettes.com/forums/showthread.php?t=148338

[tommyg29]

I will be following this thread...looks like I need to replace my valve seals, and hopefully thats all.
Sometime during the week I will be removing the rocker shaft and need to pick up a spring compressor tool.
Never done it before so....
Good luck to you too Shadango. 

[shadango]

Replace all the springs.  Check the new install.   It's not all that uncommon to break one... Particularly if they are no name specials

Steve

Yeah, I am leaning to changing them all out...."if one is broke...."...plus, like I said, I have no idea what springs are in there to match....plus a new one would be slightly different than a used one, right?

My big worry here is finding the right ones to install.

[shadango]

I will be following this thread...looks like I need to replace my valve seals, and hopefully thats all.
Sometime during the week I will be removing the rocker shaft and need to pick up a spring compressor tool.
Never done it before so....
Good luck to you to Shadango. 

Thanks! never did it here, either!

[Strawdawg]

Relatively easy job. Install new seals while Springs are off.  If the car did not have a bad/big loping idle then assume it was one of the smaller purple cams. Check the spring specs that Mopar shows and buy something equivalent

Steve

[footin70rt]

Did this engine ever sit not running for an extended period of time, a year or more? I've heard of instances of a spring fatiguing from sitting compressed for a long time. Just another thought to ponder. Either way I would replace all the springs as a set.