What were the failure rates of the sodium-filled exhaust valves of the 80's?

We have all heard stories of sodium-filled exhaust valves breaking, but how often did that actually occur?

My Dino had the engine rebuilt at Ferrari of Los Gatos in 1984, the exhaust valve part number used being different than what is in the 1970 parts book.

I don't know if this means Ferrari had improved the valves in the interim, but assuming they had, what was the failure rate in 308's of the early 1980's?

Jim O

 

It happened to my 78 308 at 34,000 miles in 2004, before I got it. It does make a mess of things when it happens, but it allowed me to get the car at a price I could afford. Notice I didn't say it was cheap.

TomB

 

We "worry" a lot in the 308 Section, because "it happens", but to take the opposite view, there are a LOT of sodium valves out there (still used in some modern motors) so statistically, "the odds" are in your favor..

But, if it is YOUR car that breaks one, they are not.....

Conventional wisdom is that any time you have one in your hand, throw it away and replace them with solid, modern alloys.

To clarify, Ferrari used them in 308s from the very beginning...1975 - 76....

 

as a complete aside, know a very experienced porsche engine builder and asked what he would use in a stock rebuild (not for a track engine for instance) that had OEM sodium valves and the answer was...sodium valves. think he would add an exception for 911 turbo engines as well.

 

I too would be curious on the number of failures. I replaced my valves with modern ones during a complete rebuild so I have no worries but I am curious.

 

My guess is that it's a very rare experience. I can only recall one incident on this site and I suspect the owner took the engine well north of what's considered safe RPM. There's hundreds of 308s and thousands of Alfas out there running sodium valves. I don't believe that either had a recall or service bulletin on this. Inevitiably engines will drop valves. ANY engine. Stuff happens......

 

There is probably a higher instance of engines in black cars failing than engines with sodium-filled valves.

 

eg, used in C6 corvettes.

 

I had an exhaust valve failure on a 20K mile 1969 Porsche 911T. In 1971. It did not break off like Na filled valves are supposed to do. What happened was that the Weber carbs were running rich most of the time in city driving, and when I went on a cross country vacation from OKC up through Canada, down to California, and back across the mountains of Colorado, the carbon built up in one of the cylinders started to flake off. A piece stuck in the valve seat of one of the exhausts, and it made a little channel in both the valve and the valve seat.

Note that I said BOTH.

Top overhaul fixed it, but I was a young kid and never trusted this car after that. Traded for a fuel injection 1972 911T.

 

a quick search of this forum for "sodium valve failure" shows that is not true, there's quite a few more than one.

In a recent thread http://www.ferrarichat.com/forum/showthread.php?t=360977 , forum guru davehelms posted this:

Just in his own personal experience, that's 5 engines.

 

Sodium filled valves were not used in 911T only the S and turbo and race cars of course.

 

Out of the thousands he has worked on, in his career.

And read the notes, on the revs..but the Ferrari engine, even with the stock flywheel, is eager to rev like that...I have missed a shift to second gear once and put 10,500RPM on one.

It knocked all the carbon of the valves, I could see it glowing in the road, but the valves made it...I would not try it twice.

RAMMER and others here have had it happen (1976 'glass car)...some of us suck it up and fix it, most later 308/328 owners throw in the towel and give up the car.

Depends on the stamina of your wallet.

 

Follow Dave's advice, that is what I do.....

 

Not a month ago when my 308 was in for service, another cusotmer's 308 was in having a complete engine rebuild due to one of the sodium valves breaking. I think the car is a carb car and had about 75k miles on it. I was told it was not being driven hard, just cruising down the highway. In my opinion, I wouldn't have a car with them. They need to be changed.

George

 

happened to my euro 1978 308 back in 1992, the PO installed SS valves...

 

I'm sure that it has been said somewhere here before, but I can't recall.....

Does anyone know what year Ferrari stopped using the sodium valves ---- did all MY of the 308 /328 engines have them ? Or did the later ones get something else ?

 

Comparing Ferrari sodium valves with 8mm stems to Mercedes sodium valves with 10.5-12mm stems or Porsche sodium valves with 11mm stems or American sodium valves with 3/8 stems or Alfa Romeo sodium valves with 9mm stems really makes no sense.

The comparison should really stay apples to apples and none of those are. No one else that I am aware of uses 8mm sodium valves with wafer thin steel walls so no one else I am aware of has a problem.


The very first major Ferrari engine repair I ever did was a Lusso with a broken valve. That was about 37 years ago and it was a well known problem then. It had new valves and new guides so blaming it on worn parts doesn't cut it either. The valves were a bad idea then and with modern metallurgy there is zero reason to use them.

 

All 2 valve motors had them.

No 4 or 5 valve motors do.

 

The only topic that has more threads devoted to it than sodium valves is timing belts.


A simple search will tell you far more than you want to read.

 

My '77 is apart right now and I'm switching the sodium valves out as a precaution.

 

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sticky buttons, sodium valves, the only cars I ever owned that come with a 'to do' list, just sayin'

 

That DID leave a mark !!

I can fix the head.

 

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Does not happen very often. Cost a fortune every-time.

Here is what's left of my 12th cylinder (98400km). Valve impact highlighted in red. Good opportunity to straighten the crankshaft, weld some cracks in the heads, bore the sleeves, replace all bearings, replace all pistons, a few rods, etc.

(It's got stainless valves now).

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