Broken Valve Spring

[UglyMutt]

First, my car has 20k on it and have had it for almost exactly 2 years.

Has anyone broken a valve spring? Today on my way to work I felt like my car may have misfired a couple times, then the check engine light came on flashing, then the car died. I pulled over started again and it idled really rough at about 500 RPM and I shut it off and got a tow.

My dealership got into it and say that I broke a valve spring on the exhaust side of Cyl 7. They said that they had never seen this before but they should have it fixed in a couple days as they need to wait for a part. Easy enough. I asked if they checked the cylinder to see if anything fell into it? They said nothing could have made it into the cylinder and the parts were all up top.

Now I’m wondering if the valve or piston could be damaged by losing a valve spring? Are these interference motors? Has anyone ever heard of this failure mode? I just want it all to get fixed once instead of having bad compression in one cylinder because of a bad valve seat or something.

Any thoughts?

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[wildcatgoal]

Will probably be fine. Any specs of metal were probably blown into/out the exhaust.

 

[PatrickGT]

Ask the dealer to provide proof that there was no damage to any cylinder by performing and printing the results from a compression and leakdown test on every cylinder.

 

[UglyMutt]

Leak down and compression would be good and easy but how do I know if the piston has been hit?

Is this an interference motor? I would expect that if you lost an exhaust spring, the valve could fall down into the cylinder?

 

[cop on my back]

If it was only the spring that broke, the valve could very likely not have contacted the piston. I would ask if they used a bore scope camera to look inside the cylinder to confirm.

 

[UglyMutt]

Yes, this was the only spring that broke. The parts will be in tomorrow and they should have it fixed. They said they have a scope and can check the piston and underside of the valve.

Also, the service writer (i trust him) told me that this is a freewheeling motor and not an interference and I think that backs up what I found online. We'll see what they say tomorrow but it sounds like this is just a fluke and not to big a deal.

 

[havasu486]

What was the result?

 

[UglyMutt]

They put in a new valve spring. A couple days latter I had an issue with a cam phaser on that bank. Probably related but not sure how. They put in a new one and haven't had any issues.

 

[strengthrehab]

I had a similar issue, but intake valve spring on #6. Valve was held by keeper and no internal damage, no contact.

 

[havasu486]

I had a valve spring break with less than 5500 miles on my first motor. Luckily the valve stem bent so there was no contact. Ford replaced the motor. That motor was bad from the beginning so the car was replaced. No issues with car #2.

 

[BreckinHardin]

They put in a new valve spring. A couple days latter I had an issue with a cam phaser on that bank. Probably related but not sure how. They put in a new one and haven't had any issues.

what ended up being the phaser issue?

 

[Adam the Lighting Guy]

You're lucky. In the SBC world, if you loose a retainer or retainer lock, or break a spring, you drop a valve. Not into the cylinder, but the valve will drop into the cylinder far enough for the piston to just give it a kiss and then the valve is bent, and no compression in that cylinder.

 

[Johnny Rockit]

Ask the dealer to provide proof that there was no damage to any cylinder by performing and printing the results from a compression and leakdown test on every cylinder.

Even then, I would pull the #7 spark plug and put a borescope in there to have a look if it runs rough. Leak down test aftee that. A "slightly" bent valve will not hold compression.

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