Sodium Exhaust Valves

Hi Anthony,

by yourself as

Hi Anthony,

by yourself as a DIY project or in a shop?

Either way it's a pretty large job. While it may be possible to get the front head off in the car, on the early cars I pull the engine. Steam Clean the heck out of it, then pull the heads, send out to the machine shop for new guides and SI Stainless valves, plane the Intake Manifolds bottoms to head surfaces (if the slightest warping is found), all the misc. servicing, like new hoses, water & fuel, Carbs, Carb Bases & Gaskits, Distribs, etc., then back in the car. I think realistically one could spend 40-60 hours on the job depending on conditions plus the machine work, plus the parts, Gaskit Set, Ex. Valves, all guides, belts, tensioner bearings (if needed), hoses as necc., valve adj. shims, etc.

I think parts & machine work could easily run $3K alone.

HTH's

Regards, JRV

Hi Harald, Welcome Aboard !! I

Hi Harald, Welcome Aboard !! I hope you will feel as free to help us from your experiences as we do sharing ours.

To your valve question:

When the heads come off an older Ferrari Engine that used sodium valves they should be replaced with Stainless Steel Valves.

SI Valves seems to be a good source for Stainless Ex. Valves as well as guides and seals.

There web addy is www.sivalves.com

As to the seal question, the debate rages whether rubber or teflon is the best, my personal preference is the teflon as they allow a little oil in while causing little friction on the stem. There are many arguments that can be made for either type, so truthfully on a street engine it's hard to say one is best or better, because a head is rarely if ever taken off due to simply seal issues, unless they were improperly installed somewhere along the way. When someone says their guide seals are causing oil consumption what I see generally is a fair amount of guide wear that is more likely the culprit imo.

You reminded me I need to put the SI Valve link in the Resource Area..thanks.

Glad you like the atmosphere here and hope you'll hang around.

Regards, JRV

Ken,
Sodium valves can be an

Ken,
Sodium valves can be an issue for most, if not for all cars that use them. Virtually all Italian cars of the late 60s, 70s and early 80s used them. Personally, I had been running sodium valves in my 365BB for almost 20 years without any problems...as well as countless race-preped Alfa motors.

During a recent rebuild, we did change them out to conventional SS valves, as well as guides, seals...and all the other worn components.

Factor the cost (of replacement) into the purchase of the car? Sorry, but that doesn't make alot of sense to me, as the market has already determined the fair value of these cars...potential engine issues aside.

Ball park:
Remove engine for typical 30K service
Remove heads
Replace all guides and exhaust valve
Check heads for line-hone
Check cams-repair lobes/replace cams as needed

$5,000-12,000, if doing a complete service

Would I personally pull the heads off a known solid engine BB because I suspected sodium valves...likely not (and I didn't)

Regards,
David

Hi........

News to me that

Hi........

News to me that the Boxer engines have sodium-filled exhaust valves ?!

The idea behind that type of valve: promote the dissipation of heat. Sodium metal evaporates at the bottom of the stem and condenses at the top of the stem to create a heat cycle inside of the hollow valve stem itself.

Problem: after shut-down, the valves still contain hot sodium metal and cool air can enter through the exhaust manifold or the intake manifold if the valves are "open" to any degree. Result: cracks in the valves.

This problem arose on the Shelby 427 engines during early deveoplment. Perhaps the Boxer engine configuration prevents the movement of cold air around the valves after shut-down...hence a longer life for the exhaust valves on the Boxer.

Frank.........23005
www.masiarz.net/bb_resource

I'll throw in here also.

I'll throw in here also.

Boxers are not really known for valve issues, 308's are.

Like Frank mentions, some engines were/are prone to sodium valve problems, others not. Another very problematic engine was the early 911's..like 308's valve heads falling off wasn't that uncommon. Also I agree with Frank that there are several unerlying issues that cause some engines to puke sodium valves and not others. I've never personally seen a Boxer engine that a valve head fell off, otoh, I've seen a number of 308/911 engines with this issue.

I've heard plenty of theories over the years, some make sense, some I wonder about. Bottom line is since certian models are prone to the failure they are the ones to be concerned about, in 308's for example the concern is real enough that no engine builder of note would leave the old sodiums in if the heads were off for any reason, if the heads aren't off....well....it's hard to justify fixing a problem that hasn't occured yet, so judgement calls are probably best left with informed owners.

Regards, JRV

Well, actually the question ha

Well, actually the question has been answered plenty of times, but one time


Ferrari stopped using sodium valves when they moved to 4v's per cylinder.

I have some souvenior pistons with holes also for non-believers ...

While the valves can and do break without warning, many guys get lucky and need head gaskits, or valve guides before the valves break, and get them changed (upgraded) to stainless in the process of taking care of the other problems.

Regards, JRV