'79 SC--Broken Valve Retainer--Replace 1 or 12?

[t-cup]

In the midst of a valve adjustment, I came across this, crack in the valve retainer on #6 intake. The motor is out, as I'm doing a bunch of cleaning and 'while you're in there' tasks. The car has about 200k, and I think it's had a top end rebuild, but am not positive.

Here's #6 intake, crack is between 12 and 1.


I searched for valve retainer issues on the forum, but didn't find much, and from the few folks I've talked to, this does not seem like a common failure point. Anyone know what usually causes these things to fail? Could it be a symptom of a larger problem that I'll need to address?

I'm now wondering...

Do I bite the bullet now, spend the small part cost (but likely significant labor/hassle) to replace all 12, or just replace the one and forget it?

Thanks!

Tim

[Steve@Rennsport]

Those are sintered metal and I'd replace all of them.

Consider yourself very fortunate that it didn't break for you,... .

[sc_rufctr]

At a guess the car may have been stored for a long time and when the engine was stopped that valve was open. As I said that is a guess but there's now way to know why this happened.

Often people buy 911s because it's their dream car but don't understand or aren't prepared for the running costs or the reality of driving a vintage sports car. (my car is 31 so she's vintage) Then for whatever reason they're stored away. Occasional use can cause some unexpected problem.

I would replace the failed one and drive it... Enjoy your 911 and give it a good "Spanking" every now and then. They really are well built cars. And their reputation for being reliable and robust is well founded. The SC in particular are considered tough.

[DUK]

I'd take Steve's advice (as usual) and replace them all. I'd also check the springs. I would venture to say they are weak and possibly letting the valve bounce at max lift. This is very hard on good retainers, let alone sintered iron.

Count your blessings and good luck.