Any preservation tips for SSI

[TSwede]

The set of SSI exchangers I just bought (see earlier post asking for oil pipe info) are in pretty good shape but there is some surface rust. Especially on the header pipes that come out of the exchanger - the shroud is perfect. I don't fancy replacing them again in any big hurry and even though they are SS they have obviously seen some action. Does anyone have any preservation tips before I put htem on.

[911nut]

If the rust really bugs you clean it off with some Scotchbrite or a wire brush but your car will rust away before the SSIs do.

[Wayne 962]

Surface rust? If I recall, I thought that the SSI units were 100% stainless - tubes and all.

Are you sure it's not some other type of corrosion?

-Wayne

[82SC]

are you sure it is surface rust?
those pipes do change color from the intense heat and the such...maybe it is that you are refering to?

[KTL]

Have the SSI's ceramic coated and you won't have to be bothered with the discoloration issue any more.

[Formerly Steve Wilkinson]

Can't be rust. They're stainless steel.

Stephan

[john walker's workshop]

low grade stainless rusts. the delorean guys use scotchbrite pads to keep that brushed look.

[island911]

I don't know what type of stainless is used for SSI's; but there are lots of types. Steels get their “Stainless” name when Resistance to corrosion is made by the addition of chromium to the base Iron alloy.

In general, Resistance to corrosion is not the only thin to go by when selecting a Stainless steel. Just look at the SSI’s construction; formability, machinability, weldability are three other considerations for SSI to think about. And then there’s high temp performance. There is a Best stainless for each of these catagories, with trade-offs in the others. So “low grade” is really just “different grade”

To answer the original question “Does anyone have any preservation tips before I put them on.”
Polishing stainless help prevent corrosion.
Also, keep alkilies (basics) away. I’ll go out on limb here and guess the PO use some high sulfur content fuel.

---

'81 SC COUPE

[TSwede]

I've read all these and they are very helpful. The rear box is OK with yellowy brown surface stuff that will polish off. Also the heat exchanger shrouds look mint under the oily crap that is on them. It is the tubes that are rusty (not rotten) - they have the appearance of bog standard manifold tubes off any car. Are there conbination types made with different types of steel for the pipes?

[TSwede]

What exactly are SSI systems. Are there other standard ones or does this term refer to any pre-whateveryear system as long as it's stainless steel????

[911pcars]

SSI is the manufacturer; Stainless Steel Inc.

Sherwood Lee
http://members.rennlist.org/911pcars

[Jim Sims]

There are SSI's and there are SSI "knock offs". The real SSI's are built by the company in Novato, California completely (exhaust headers or pipes and heater box) out of grade T-304 stainless steel. 304 is an austenitic stainless steel and a simple permanent magnet will not typically stick to it. It may discolor from heat and perhaps there may be very slight corrosion near the welds in some severe duty applications. More often they are discolored by oil dripping on them and burning. If the exhaust headers are rusty and a magnet sticks to them these are one of the SSI imitations that merely have the heater box fabricated from stainless steel. Jim

[911nut]

There's ferritic stainless and austenitic stainless steels. Both contain varying amounts of Chromium (as Island911 mentioned) for high temperature oxidation resistance. Most OE manufacturers use ferritic stainless steel because it's cheap and easy to form and weld.
Per Jim Simms, SSI is using austenitic stainless. Any "rust" that's showing up is iron-based surface contamination from the atmosphere. Since it's just laying there Scotchbrite should take it off with little effort.

[RoninLB]

I like Jim Sims approach [as usual] with the magnet. I live on a sand bar and any time I go into marine supply for stainless I bring a magnet. No magnet attraction = very good, slight magnet attraction = good, more than slight magnet attraction = not good. I have worked in boat yards and stainless gas tanks will some times/eventually leak at the seams because [I think] the oxygen gets trapped in the welds. Good stainless deck hardware will look good fore ever, "not good" stainless deck hardware will look cheap/rust spots/pitting after 3 years. Get a magnet and explore what you are dealing with.

[Wayne 962]

Knock-offs? That's funny, considering that the SSIs are knock-offs of the OE units...

-Wayne

[RoninLB]

WAYNE... my impression of Jim Sims "knock- offs" is that some one may have "boot-legged" SSIs in between shifts at the local Manderin cookie factory.

[TSwede]

I'll have a close look next time I go down to the garage.... not that it matters now because I've already bought the full system.

Are they marked/stamped up in any discernable way??

[Jim Sims]

I guess that would make them 2nd order "knock offs". The point I was making is that there are apparently units out there that have only the heater box section or shroud made of stainless steel and the exhaust or header pipes are carbon steel or some other less corrosion resistant alloy than 304. The ones made by "SSI in Novato" are all stainless steel (at last the one's I've seen and read about for 911's) and when people say "SSI" in the context of 911 heater boxes this is what they are expecting. Cheers. Jim

[TSwede]

I'll have a close look next time I go down to the garage.... not that it matters now because I've already bought the full system.

Are they marked/stamped up in any discernable way??

[marcesq]

TSwede:

Call John @ SSI. He is the owner of the company, and one of the nicest people you will ever talk to. His number is 800-227-1486. He will gladly help you identify whether your system is in fact his product.

Good luck.