2 V cars exhaust SODIUM VALVES warn

Picking up my engine from shop today had the valves changed and other misc while you're in there stuff. My sodium valves were flawless at 60k miles. This fchat is borderline fear mongering. All this replacing good parts is probably gonna stop my entire project. I am way over budget now. Was wondering does running the air pump create more heat and damage the valves? I don't have the pump on my car.

 

I don't think it's fear mongering, more fact that these things break. Spend a couple thousand on the repair or up to 20K on a rebuild. It sucks but it is more fact. I am sure they all look flawless right before they break.

 

All Boxers and 2-valve Ferraris have 8mm valve stems. 7mm valves were introduced in the QV and TR. None were sodium filled.

 

Not arguing about doing "preventive" maintenance, but doing a complete vale replacement is going to cost significantly more that a typical 308 major. In addition to belts, fluids, tensioner bearing and valve adjustment you are talking pulling the motor, disassembly, the valve job with all new valves, maybe replace guides, reassembly and installation. At that point you mine as well do rings and bearing too. Actually, IMO the money would be better spent by trading up to a QV.

 

At 64,000 miles my valves looked OK but out they came while it was apart.

 

I suspect you are unlikely to detect impending failure of a sodium filled exhaust valve. I would bet this is a fatigue issue and once a micro-crack reaches a critical size, failure will occur shortly afterwards. Fatigue is associated with reversible loading cycles and is proportional to the number of cycles. Typically, 1-billion cycles is the threshold of what is considered infinite fatigue life, though this could vary with the application. In the case of valves, operating at 5k+ rpm, I think you need to think another order of magnitude for infinite fatigue life. The other thing is fatigue life is material and load dependent. Fatigue strength for a particular material is generally presented on an Stress vs cycles (SN) chart that is established empirically, or in other words by test. The higher the stress, the lower the allowable number of cycles. The higher the number of cycles, the lower the allowable average stress.

Bill

 

The Heads on these cars are hard to get off but other than that the job isn't that bad-much easier than a bottom end rebuild (of course) which you'll need if one breaks. I've had mine for 6 yrs and bought it knowing I'd eventually do this fix-but damn the compression is stellar, it leaks nothing and nobody really knows what happened with the 1st owner, h passed away. I know he did good work bc I see other things he fixed as I fix issues that come up. He may have done it and Damn I don't want to pull those heads off as clean/tight as the engine is

 

Here are the sodium filled valves that came out of my old 308GT4. From the exterior, they looked perfect....but one small tap and they broke.

Replaced them with stainless steel and never have to worry again until they're worn out.
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Alfa Nord engines have sodium filled valves too ... will have to break one of mine to have a look one day. New valves will be installed when it's rebuilt of course.
Pete

 

HEAPS of cars run sodium filled valves with no problems. Good old Ferrari, hey?

 

Yeah, same with rubber timing belts and their pulleys.

In all my years of being aware of cars I have never, ever, and I mean ever, heard of anybody replacing a tensioner pulley on a Honda, Toyota, Alfa Romeo (even, including myself with my old Sud race engine ... just used the best couple we had, and they were all fine) for a rubber timing belt system, and yet according to this site you are a complete moron if you do not do so and your timing belt will shred in minutes.

While I accept Italians can be a bit stupid, and some of their designs lacking, some on this site need to remember that Ferraris are JUST cars and the 308 engine is really just 2 FIAT 124 engines on a common crankcase (or maybe the FIAT 124 engine is just half a 308 engine). My sister ran one of those things (actually a 125, but same engine) and while it was not perfectly reliable it never had timing belt issues and she probably never opened the bonnet ... I do remember complaints on the amount of petrol it used (but of course she was young and driving all over NZ's north island).
Pete

 

Now those are some impressive valves!

 

Ferrari's supplier. Just like their "sticky" interior supplier.

 

Sad but true.... But it's still up to Ferrari to pick their suppliers and choose the specification.

 

Really? I don't know of a single shop in my area that does not replace the tensioner bearing when the timing belt is replaced, regardless of the type of car. And it's not just to jack up the cost. A TB for many cars is under $20. Some under $10. The question I would ask is that at those priced why would you not replace it?

 

You make a good point, but my point not clearly made is I've never heard of a TB being less than perfect.

The very expensive Alfa Sud race engine I had built (200hp, 1600cc 2 valve per cylinder) used a couple of old tensioners that I had and they had likely done over 100,000 km's and were still perfect ... didn't even consider buying new ones.

My work-and-back hack, bought off the side of the road, Honda Odyssey has now done over 237,000 kms and yes I've done the cam belt (and balance shaft belt) and the tensioner was perfect. Old belts flicked off, new belts thrown on and bolted back together and 20,000 km's later she's going fine ... other than it leaks a lot of oil (not worth fixing ... just buy another).

So while I get your point, I believe that perfectly good tensioners are filling up our rubbish landfills for no reason ... like a heck of a lot of other things that are thrown away for no need.
Pete

 

Might be your personal experience but unfortunately failure of tensioner bearings is a common occurrence. A dealer changed the belt on my parents' Maxima V6. The bastard apparently changed the belt but not the tensioner (he charged for it). Fast forward three years, and the car is now handed down to my son. He put 10k on it before the bearing failed with catastrophic results. We turned it into a teaching moment for my son and the rest of the summer we repaired the motor. One piston, one rod, one incredibly talented aluminum welder and several new valves later, the motor was running like new but it all could have been avoided if the bearing had been changed. You could look at it as cheap insurance or necessary maintenance.

 

These look like they are ready to go back in. Heck, with my luck my valves are probably in identical shape and I'll be taking a similar pic when one of them finally snaps and I have to do a top and bottom end rebuild

Another thing the prev owner of my car did was replace the cam pulleys with steel ones, it's a 75 so they were plastic at one point. If one of them failed yrs ago (and made him switch to steel) he would have had to some sort of rebuild. The compression and lack of leaks/burning oil may indicate he did a full rebuild, but who the hell knows. This pic is just scary. Uuuugh.

 

Yup, i remember reading about a guy taking the sodiums out and accidentally dropping one of the old ones on the shop floor, when it promptly snapped in half.
I am also the type who does not panic over oil changes or belt changes, but a valve breakage occurrence is so serious in terms of damage, that I would do the change too.
Oh yes and do change tensioner bearings, but do let it depend on mileage as well. 60kmiles or 6-8 years is a good interval for most in my experience. Most of the times it will warn by becoming audible well before it breaks anyway. Of course if you don't know how to recognize that or even ignore it, well...

 

Shocking that he charged for it!

Maybe the replacement was not of good quality? And if you can purchase TB's for like $10 I would be concerned about the quality. What is the replacement frequency for a Maxima v6 timing belt? ... assuming 20k per year by your parents plus 10k by your son, adds up to 70k ... but I assume it's 100k being Japanese.

Anyway good bonding or teaching lesson, and yes I hear you and johnk BUT while a tensioner bearing is doing a very important job the load on it is bugger all (rubber timing belts do not run at huge tension) and unless Ferrari purchase the cheapest possible bearing made on Earth should out last the original owners life!
Pete

 

Sorry, but my opinion is, that this valve replacement thing is complete paranoia.
You simply cannot prevent all hypothetic failures on mechanical things, except if you don't drive the car.
Latest experience: An Opel GT owner here restored his car to concours condition and after approx. 1000 kms the carburettor float chamber developed a crack. Car ist toast now.

However, it is understandable, that workshop owners recommend such projects like preventive valve replacements if they are aware of the financial circumstances of the car owner.
'Hey, this guy has money and no clue. Let's scare him a bit'


Best Regards
Maerin

 

Hi Martin,

Can you explain the valves out of my old car then?