Sodium Valves ?? What a time bomb, I did not know !

Frankly, if I had an engine with sodium-filled valves, I would replace them. The concept SEEMS to make sense - pull the heat away from the valve head. But a sodium valve doesn't eliminate heat - it just moves it. And if the valve does not receive additional other cooling - air/oil/whatever - it just creates MORE heat in the valve stem area than a standard valve that the valve stem and valve guide have to deal with.

So unless the engine is designed to have a lot of cooling media (usually oil) in contact with the valve, sodium-filled valves create a problem - more heat in the stem and the valve guide - that does not exist with a standard valve.

 

Lots of engines use the technology, it's not a "Bad idea" Enzo dreamed up, one night....

Change 'em out, if you want to.....

I'm gonna do mine when they need it.

I think it's an "engine out" as no way you'll do the rear bank in the car.......it'll be a real surprise to find them already changed, in the history of your car.....no????

 

Andy,

Rifledriver addressed this directly yesterday and he has professional experience - not just opinion. I copied his post below.

Jim


Originally posted by jim400i:
Do you have any sense re the incidence of failure on 2v 308s? Do you recommend replacing the valves in an otherwise sound 2v engine?

Response from Rifledriver:
It does happen but is not high on my list of things to worry about but I do not own a 2 valve car either so it is easy for me to say.

By the time it is out and apart a lot of excuses can be found for the job to snow ball. If you had a good running motor that you are satisfied with. I don't see anything wrong with just taking the heads off and installing a set of valves and stem seals. You would need to check the quality of the match of the valve seats to the valve faces. Lots will scoff at that but in reality it will put you exactly where you are now as far as the condition of the motor but you will have peace of mind.

If you were able to do the work yourself it would not be that expensive to do. Doing a good complete valve job is better still but at a greater cost.

 

Did you perhaps miss the other thread currently discussing this?

Sodium filled valves are an ancient technology that were widely used on aircraft engines in WWII. Improvements in modern engines have made them obsolete. Ferrari used them on engines up until the 308 QV was introduced.

They do seem to have an inordinate propensity for failure (discussed in the other thread) but aren't cause for immediate panic. Many engines have been running for many years without failure but occasionally one breaks and if it's yours it's a big deal.

If your engine is in otherwise great condition and you only drive the car occasionally and your "risk-tolerance" is at a comfortable setting, there's probably nothing you need to do.

If you find yourself worrying about timing belts and water pumps and sodium-filled exhaust valves, etc. to the point that it is compromising your ownership experience, then a pre-emptive "engine-out" might be for you. It won't be cheap and it might not be quick either. Right now is the time to do it though, before Spring and you really want to exercise your new "Peace Of Mind".

 

i look at it this way. I am NOT going to pull the motor and change the valves because they *might* break. It isn't a real common occurrence, but it happens.

Not having the valve clearance correct with appropriate shims will let the valves slam shut or not fully seat rather than a gentle close, so improper shim maintenance will exacerbate the problem

If a valve DOES break on my motor, it seems like real good excuse to upgrade my block to 3.5 liters during the rebuild. AFAIAC, if the block number matches the car, who cares what is inside. I don't think the concurs judges will be measuring bore and stroke and cam specs.

Doug