SS HEs - Can I weld ends to plug this up?, ...the open ends of the outer heater shroud? Options

[Mark Henry]

They are SSI's, they changed small things each production run. Early SSI's (like mine) had mild steel flanges and are the ones that are usually rotted.

[Katmanken]

You need to be careful welding stainless...

Some grades will crack years after after welding...

My metalurgy teacher always cautioned about that and cited a law suit for a stainless steel fire extinguisher filled with dry powder. The bottom of the extinguisher was seam welded onto the can.

All the overpressure tests at the factory showed the welds were fine.....

However, about 5 years later, when somebody activated the CO2 container in the fire extinguisher to blow out the powder on a fire, the bottom blew off the can and embedded itself in the operators foot.

Metalurgy tests showed that the stainless used weakened over time at the seam weld and broke...

Not knowing the types of stainless, would you like to risk a crack in the pipe inside the hot air shroud after you welded the shroud to the pipe?

[andys]

30+ years ago, I made my own HE's on a 914 turbo exhaust sytem. The fabricated sheet metal HE's were brazed (not welded) to the header. Worked great, completely sealed, and no cracking of the braze joints.

Andys

[Katmanken]

I think something else you get with the normal crimp fitting is a ltttle adjustability with the heat shrouds on the pipe so that you can ensure the other heater parts attach. If you weld and it warps, you could be in for fun.

An old engineers saying: "if it aint broke, don't fix it"

[tracks914]

I used Permatex Red High Temperature Silicone to close up the gaps in my H.E.'s. So far so good. Why not, GM uses it on all there exhaust manifolds!!! Before changing the ends to SS I would consider using the HT Silicone to seal up the gasket surface and fill in the rust pit marks.
BTW I beleive the header pipes and the HE shrouding have a different rate of expansion therfore you can only weld up one end. If you don't then they will crack for sure. Silicone will allow quite a bit of expansion and contration.

[Tom_T]

Thanx for the plethora of tips guys! (IMG:style_emoticons/default/beerchug.gif) ...just what I was looking for!

Thanx for identifying them as SSI's as well! (IMG:style_emoticons/default/smile.gif)

It sounds like the safe & sane solutions for the HE shroud end gaps is to seal with HT flexible exhaust sealant, to maintain flexibility for expansion/contraction & to avoid potential cracking! (IMG:style_emoticons/default/smile.gif)

And possibly that or copper permatex on the existing flanges, unless the old ones can be properly replaced with the new SS flanges that I've already bought! (IMG:style_emoticons/default/huh.gif)

The one dog-ear to attach to the head ex-manifold is cracked as in below, which I've been told can be welded to repair - TRUE???? (IMG:style_emoticons/default/confused24.gif)



(IMG:style_emoticons/default/idea.gif)

[tracks914]

Thanx for the plethora of tips guys! (IMG:style_emoticons/default/beerchug.gif) ...just what I was looking for!

Thanx for identifying them as SSI's as well! (IMG:style_emoticons/default/smile.gif)

It sounds like the safe & sane solutions for the HE shroud end gaps is to seal with HT flexible exhaust sealant, to maintain flexibility for expansion/contraction & to avoid potential cracking! (IMG:style_emoticons/default/smile.gif)

And possibly that or copper permatex on the existing flanges, unless the old ones can be properly replaced with the new SS flanges that I've already bought! (IMG:style_emoticons/default/huh.gif)

The one dog-ear to attach to the head ex-manifold is cracked as in below, which I've been told can be welded to repair - TRUE???? (IMG:style_emoticons/default/confused24.gif)



(IMG:style_emoticons/default/idea.gif)

That one is an easy fix. 2 minute job, just be sure the welder uses SS welding rod.

[SirAndy]

They are not welded for a reason ... To keep you alive ...
(IMG:style_emoticons/default/popcorn[1].gif) Andy

How so Andy? (IMG:style_emoticons/default/confused24.gif) ...please educate me! (IMG:style_emoticons/default/popcorn[1].gif)

I think Andy's point is that weld beads can crack, and a crack lets CO into the cabin.

And I agree with Andy. With the flex that occurs in the whoe exhaust sytem, cracks are bound to happen. Will CO sneak in? Could be. I would leave it alone. My SSI's are 35 years old. Yeppir, there is some degredation of the red sealing compound they originally used on the ends. Until the shell rattles I'll leave them alone.
Pat

(IMG:style_emoticons/default/thumb3d.gif)

[jd74914]

That one is an easy fix. 2 minute job, just be sure the welder uses SS welding rod.

I might have missed it, but I didn't see anyone mentioning passivation. Once stainless is welded, it looses it corrosion resistant properties at the weld bead/heat effected zone. To regain these properties it must be passivated. It’s a relatively simple process, but uses some acids and chemicals and so is (IMHO) impractical to do at home. Without passivation the joints will rust. I'm used to working with deionized water which is very tough on metals, but I would imagine that road salt has equal corrosion capabilities.

Personally, I wouldn't be too worried about the weld bead cracking (though it would be a concern). Once again, my main concern would be the loss of oxidation resistance. Anywhere that jacket is welded will have an increased propensity for rusting. IMHO its not really a big deal fixing the mounting ears, and running without any treatmet because of their location. I would leave the rest of the heat exchanger alone unless it really needs help (which it doesn't look like from the picture). Like someone above said, if it works, don't fix it. (IMG:style_emoticons/default/smile.gif)

[Mark Henry]

I had the same crack on the ears, just weld them up.

Another thing you have to look out for on SSI's is that you don`t over torque the exhaust nuts. I`ve seen the tube around the ears start to deform if you over torque the nuts. This is also the most likely reason the ears are cracked.

[Tom_T]

That one is an easy fix. 2 minute job, just be sure the welder uses SS welding rod.

I might have missed it, but I didn't see anyone mentioning passivation. Once stainless is welded, it looses it corrosion resistant properties at the weld bead/heat effected zone. To regain these properties it must be passivated. It’s a relatively simple process, but uses some acids and chemicals and so is (IMHO) impractical to do at home. Without passivation the joints will rust. I'm used to working with deionized water which is very tough on metals, but I would imagine that road salt has equal corrosion capabilities.

Personally, I wouldn't be too worried about the weld bead cracking (though it would be a concern). Once again, my main concern would be the loss of oxidation resistance. Anywhere that jacket is welded will have an increased propensity for rusting. IMHO its not really a big deal fixing the mounting ears, and running without any treatmet because of their location. I would leave the rest of the heat exchanger alone unless it really needs help (which it doesn't look like from the picture). Like someone above said, if it works, don't fix it. (IMG:style_emoticons/default/smile.gif)

Thanx - hadn't heard of that effect before, but will ask the welding shop which does the work about "passivization" treatment afterward - especially if I end up replacing the exhaust flanges.

I think I'll go the HT Red Silcone at the Jacket end joints as apparently SSI did originally, rather than either welding or brazing - after they're cleaned up from what apparently was a very leaky 2L, given all the burnt oil crud on them - of course.

Having lived in Pittsburgh PA as a kid & visiting since - I know what you're talking about with road salt! (IMG:style_emoticons/default/dry.gif)

Fortunately here in mostly sunny SoCal we don't have any road salt concerns! (IMG:style_emoticons/default/shades.gif)

However, when I lived closer to the beach - sea salt spray in the wind was a bigger concern, particularly on the top-side!! (IMG:style_emoticons/default/dry.gif)

So you Easterners & Midwesterners might keep that in mind when you're looking at supposedly "clean & rust free" CA 914s - & ask: "Where in CA did it live?". (IMG:style_emoticons/default/smile.gif)

BTW - as an Architect, I too know the "...if it ain't broke...." ethic, but keep in mind that I'll be essentially rebuilding my 914 & want to get the used parts back into close to new condition before it all gets hung on a very expensive job! There's also a saying about doing it right the first time & "You can do it fast, or you can do half at a time, but NEVER do it 'half-fast'!!!!" - so you're not redoing it again later - over & over & over............trying to find what you missed! (IMG:style_emoticons/default/smile.gif)

[Tom_T]

I had the same crack on the ears, just weld them up.

Another thing you have to look out for on SSI's is that you don`t over torque the exhaust nuts. I`ve seen the tube around the ears start to deform if you over torque the nuts. This is also the most likely reason the ears are cracked.

Thanx for the tip! I think that was the same with the OE HEs as well as on the soft alloy heads & manifolds & case of the engine itself too!

[Tom_T]

And I agree with Andy. With the flex that occurs in the whoe exhaust sytem, cracks are bound to happen. Will CO sneak in? Could be. I would leave it alone. My SSI's are 35 years old. Yeppir, there is some degredation of the red sealing compound they originally used on the ends. Until the shell rattles I'll leave them alone.
Pat

So Pat, for your CW perfection 72 - did you paint the SSI SS HE's to the stock HE & Muffler flat HT Grey, or leave them shiny?? (IMG:style_emoticons/default/confused24.gif)

If left shiny, does it work against you on concours points?? (IMG:style_emoticons/default/confused24.gif)

I need to clean up & repaint my muffler, so I could do both at the same time if that's the case! (IMG:style_emoticons/default/idea.gif)