Would I have sodium valves?

Seeing posts about the horror stories made me wonder...would I have these time bombs ticking away in my car?

Mine is a 1980 gtsi, so the 2v injected car. But the engine blew up and was replaced under warranty at around 7500 miles. I'd have to check my records, but I think that was in 1981. So...what's likely in there?

 

sodium valves

but don`t worry too much...change them to stainless steel next time you rebuild your engine
until then, keep the revs mostly below 6500rpm...
that does not mean you will be safe from a valve failure but it might be a precaution
the more worn your valve guides are the more probable a failure will be

it`s been discussed here on a regular basis over the years and indeed there are a handful examples
here on F-Chat (f.ex. see Rammer`s thread below)

on the other hand, there are tens of thousands of cars still running on sodium valves -
not only 308 2V ...also inj. Porsches, Mercedes etc...it was state of the art in the seventies and eighties...
even today there are engine rebuilders with experiences of 30 years that are still using them on a rebuild

so enjoy your car and drive it in good health -
and if the worst case should really happen...rebuild

 

Mark,

I seem to recall, "out of my head", that what we can be sure of is that the sodium valves were abandonned with the four valve heads, perhaps, according to some, because the passages for the valves were smaller and there was no place for the bigger "tails" (the french word "queues de soupapes" translated literally) of sodium valves.
So two-valves heads have most probably sodium valves; as for the one that were replaced, difficult to say...
More knoledgeable people will probably chime in very soon.

Rgds

 

Thanks. I am not losing sleep over it. I was just thinking maybe they had done something different by the time of the replacement.

 

You could replace your existing valves for stainless steel. My car had 52k miles when they went at 2400 rpm. It was running perfectly. No smoke and I never added a drop of oil.
, less than $500. What would be the cost to change them?

 

I think I just read that the next generation of Corvette is going to have sodium filled valves on either the intake or exhaust.

 

Ferrari of Ft Lauderdale requires you to sign a waiver that if a sodium filled valve goes while your car is in their care, they are not liable to fix it. This happened to the dealer recently. Interesting.

 

Plenty...8-10K at a "pro facility". Obviously far less if you could do it yourself, which I cannot :-(

 

All 308s had sodium valves until the QVs ;-)

 

Sodium-filled valves have been/are being used for many years on performance engines and are an "upgrade" in many cases for engines that are modified to make more power. Maybe Ferrari just didn't buy good ones!

 

Thank goodness I have a QV!!!

 

At $8k to $10k, I will take my chances. Odds are I will sell this 308 in favor of a qv or 328 within a few years anyway.

 

I have a '75 308GT4 with about 55K miles on it. The last time I ran a compression test one cylinder was a little low. Interestingly enough when I checked the valve clearances all were OK except for the exhaust valve on that cylinder. It was right at the lower end of the range, but still within tolerance. I decided not to change the shim, and have been worrying about it ever since.

I have a close friend who runs a machine shop and builds Top Fuel nitro and alcohol engines for drag racers, tractor pullers, drag boats, etc. He has every machine tool known to mankind and is a master machinist of the old school - no DROs or CNCs. (you haven't lived until you try to figure out a crankshaft grinder with a 60" grinding wheel and nothing but vernier controls). His balancer and camshaft profiler are computer controlled and I take care of them for him, as well as the on-board computer for a Top Fuel Dragster we campaign. This guy knows engines.

I was talking with him about sodium-filled valves and my little problem. I originally thought my lower compression reading might be from a deteriorating seat from using unleaded gas, but he said that was unlikely because an aluminum head, even in the 70's usually had hardened steel seats. The real problem is with cast iron heads because the valve seats were usually just hardened to a few thousandths through an inductive heating process.

He said that sodium filled valves were usually used only for the exhaust side to draw the heat from the exhaust away from the valve head and into the stem where it would dissipate through the guide. He said the stem of that one valve is probably stretching which caused the clearance to decrease. We started talking about pulling the heads and doing a valve job. "What kind of documentation do you have?" he asked.

I pulled out my shop manual and we turned to the section on the valve train and he almost fell over when he saw the stem diameter of the valves. "The last time I saw valve stems that skinny was on a Briggs&Stratton," he said. "Let's do a full leakdown test on a warm engine and we'll go from there."

He can get valves made in stainless or titanium in any diameter and configuration. He said if it was his engine he would put in stainless valves with a wider stem diameter and machine new guides for them.

I've been rewiring the car and doing other PM tasks, and the whole interior is out of the car, so it will be a while before we tackle this one. I'm prone to think that spending a few $thou now for insurance is a better idea than $15-$20 thou for a complete rebuild.

 

If it were a few grand, I'd do it. At $10k, I'll take my chances...

 

""The last time I saw valve stems that skinny was on a Briggs&Stratton"

Maybe that's who Ferrari sourced them from!

Clearly there are excellent sodium-filled valves available since they are used in some serious (9k RPM+) performance-engine applications.

 

Has the stem diameter on Ferrari valves changed much over the years? I'm speculating your friend's reaction says more about the difference between European engineering & US hot-rodding than anything else.

 

I have seen it posted that a rebuild after a failure could cost you $20K. I can tell you from experience it could be double.

My number 7 exhaust valve failed at about 2,200 RPM (in my driveway) and the damage included a cyclinder liner and the block. Bad, very bad.

I ended up purchasing another engine and then combining parts from both to get one working engine. The heads were machined and stainless steel valves were used. I also replaced all hoses and pretty much anything else that does not age well.

This is likely as bad as it gets. But at the same time, I probably have one of the best engines around and it will provide years of trouble free service.

 

Sodium valves typically have very large stems. The German valves I have seen for Mercedes and Porsche ranged from 10.5mm to 12mm in diameter so that there was a useful hollow space and enough stem material to be strong. The American sodium valves I have seen were 3/8's....same idea.

Alfa used 9mm stems on theirs but for the most part those motors had lower redlines and the power was in the lower part of the range so seeing redline was far less common.


Ferrari used 8mm stems with minimal wall thickness and yes, I suppose you could say they weren't very good as evidenced by the fact that they have a reputation for breaking.


With valve stem diameter never entering into the discussion comparing Ferrari valve breakage to German or American uses of sodium is just silly.

For those that want to feel safe because of the idea that only worn guides are the cause of valve breakages. Sorry, not the case. I have seen motors break their valves with perfect guides. The very first Ferrari motor I ever took apart was a low mile Lusso motor with a broken, recently replaced OE valve. I have seen many more since.

 

This may be the best sodium filled valve thread ever. Thank you Gentlemen. I'm feeling much more knowledgeable.

 

Part of the problem of these valves could be how they are made. If you take a magnet along the stem, it won't stick, but if you get to within a 1/8" of the valve keeper groove, it will. A closer visual inspection can reveal a faint dissimilar colour of the metals in that area (proving two different metals being used). The two parts are probably just friction-fused, or spot-welded together.

I've seen a broken valve and the stem walls are super-thin - probably no more than 1mm thick...

I consider myself SUPER lucky in that my motor had three BENT valves when I opened it up back in 2001. I used the Superformance S/S valves to replace them all. 11 years later and the engine is still nice and healthy.
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Hey good to see you back, haven't heard from you in awhile.

 

Very interesting - The valve I'm concerned about is also the exhaust valve on cylinder #7.
Anyone else have a failure of #7 Exhaust valve?

 

My understanding is that that #7 is the most problematic. I do not have data, only what I have heard from both those knowledgeable and probably a few not.

I would be curious in any data on failure by cylinder too.