Stock Exhaust Stainless? '97 NA same as '96 SC

Ok, maybe dumb question time....

I have a '96 SC Riv that has an aftermarket exhaust as the car was tapped in the back some time ago. Well, due to rusting out one of the mufflers is now dangling. I also have a '97 NA that I plan to strip that looks to have an exhaust in great shape on it. So the dumb questions are:

1) Are both exhaust systems the same? ('96 SC vs. '97 NA)
2) Was the stock exhaust stainless? In other words is it reasonable to expect that the '97 exhaust is in good condition?

I'm not looking to spend money on a new exhaust system if I don't have to. On the other hand, I don't want to waste my time swapping in an exhaust that's near death. Any input on the life expectancy of a stock system (northeast) would be appreciated!

1) yes
2) yes

they are the same, made of 409 SS which quickly forms surface rusts and eventually rusts out completely.

1) the exhaust systems are not the same at the downpipe but are dimensionally similar at and past the resonator.

2) The stock exhaust was stainless, after a fashion. It is T409 stainless, which is not non-ferrous. It is actually similar to the the old US Steel "Cor-Ten" family of copper/nickel/chromium alloy steels. It has a "reactive weathering" (rusting) period but once reacting at the surface the reaction stops -- sort of. Cor-ten steel formulations are A606 A588 A242 and their cousins. Automotive exhuasts are typically T409 and sometimes T439. Neither readily polishes although with some effort it *can* be done with T409. Either of those is cheaper than T304, a relatively inexpensive non-corroding and polishable stainless steel.

The OE T409 exhaust system steel, for weight reasons I am told, is thin enough so that if the exhaust system begins to react from the inside the inner patina will deepen enough, over time, to meet the outer patina and that area will perforate. If your 96 had the original exhaust most likely this is what happened to it.

If you look using rockauto.com you should be able to find shadow diagrams of the Riv's exhaust. You can also see diagrams using http://www.walkerexhaust.com/, select 'North America" from the dropdown list on the right then 'Catalog" from the list on the left. However, the best thing to do is get under both cars in turn and look. If I am not mistaken the downpipe/cat are different.

I think the least expensive workmanlike thing to do is get the Walker parts for replacing the rotted parts of your system - they are made do that you cut the old piece out and slide the new in. For instance, the little nipple into the muffler is already expanded to fit over the stock exhaust pipe. Just mind how you cut it, it's not difficult to get it right.

What I did was I ordered and installed a 2004 Park Avenue Ultra exhaust, which came with new hangers and fits fine although the oxy sensor is in a slightly different location (so I added some aluminum flashing to the heat shields) and the exhaust tips are placed as for the never-built (well, GM built ONE) Northstar V8 version of the Riv. (it was not that tough to fit as the Olds Aurora, same G-body but 4 door version, came with a Northstar v8 engine). The tips come out at the far corners of the rear bumper fascia, they *just* peek out. And since the mufflers are a little bigger and the pipes are further away from the Riv's spare tire well, no more resonance there it's darn near silent in operation.

My original exhaust (1998 Riv in service since about 1/1998 I think) lasted until early 2009, and perforated at the leading edges of both mufflers from interior rust-thru.

I painted (fogged the inside and painted outside) the replacement (except the polished plated stainless tips) with aluminum engine paint. If you get Walker parts consider painting the outsides and fogging (with paint) the insides *especially* the pipes.

Albertj

Thanks for the responses! I have a galvanized Walker replacement system in my garage I got from Rockauto as I knew my exhaust was going (again, not an original exhaust due to being hit at one point). I assume the one on it is probably some cheap job- no tips at all. The walker replacement has tips, but they're galvanized and not too nice like the originals. Since I picked up the '97 that I plan to strip after I got the Walker exhaust, I thought I'd ask. I think I'll paint the Walker tips flat black, put it on, and call it done!

Thanks again for the replies! Merry Christmas!

71gsx455-4spd wrote:

Thanks for the responses! I have a galvanized Walker replacement system in my garage I got from Rockauto as I knew my exhaust was going (again, not an original exhaust due to being hit at one point). I assume the one on it is probably some cheap job- no tips at all. The walker replacement has tips, but they're galvanized and not too nice like the originals. Since I picked up the '97 that I plan to strip after I got the Walker exhaust, I thought I'd ask. I think I'll paint the Walker tips flat black, put it on, and call it done!

Thanks again for the replies! Merry Christmas!

The Walker system, you can make it last longer by cleaning it off with dry gas or Windex or 409 or what have you, drying it, and then painting it outside with engine paint and fogging the inside with paint as well. From the factory it is misted with an oil film that kinda bakes on (that is the funny smell you get from putting on a new exhaust) and provides some protection but wears off after a short while.

By the way, if you do paint it it will stink for a while until the paint bakes on (several hours of operation).

You might want to paint the Walker tips gray to match the gray lower body moulding (unless your body moulding got painted body color at some point). For the tips any decent spray paint will do, because they don't get but so hot (I think always less than 200 F).

Bottom line for me is to look at the systems. IF the systems on the 2 cars match, I'd move the '97 exhaust over; the installation is actually easier -- it is one piece and goes *under* the rear axle beam so there's no fiddling or fishing of pipes to do. You'll have to crawl under & look then decide. If not then I'd install the Walker and hand the old exhaust in my Man-Cave or sell it on eBay for shipping plus a few $$. I think shipping will be around $120 as one piece, less if you cut it up but you have to discuss that with the buyer.

Albertj

Thanks Albert, good advice. Looks like I'll need to get both cars up on jack stands side by side and look at condition and fitment. I'm hoping to just swap over for the reasons you mention.

71gsx455-4spd wrote:

Thanks Albert, good advice. Looks like I'll need to get both cars up on jack stands side by side and look at condition and fitment. I'm hoping to just swap over for the reasons you mention.

All you really need to do is open both hoods and look at/measure the downpipes. The exhausts hang the same but the NA and SC downpipes usually differ. I can't say because I have a '98. The exhaust off my '98 would not fit a '96 SC directly, we had to extend from the '98 system's flange at the cat up to meet the '96 downpipe. If that '97 system is as nice as you say for $50 or so a pipes shop should be able to weld on an adapter for you, or you could do it yourself if you weld for shorter money. Would not recommend clamps and stock bends because of the heat, however you should be able to get stock bends and a flange of the right gauge in t409 or t304 and cut/weld them up yourself. Just sayin'.

Albertj

I would just cut it after the cat and use the 97`s exhaust. If the exhaust rusted out, you probably aren`t unbolting anything down there anyhow. I would swap out everything and have an exhaust shop do the final weld.

Jason wrote:

I would just cut it after the cat and use the 97`s exhaust. If the exhaust rusted out, you probably aren`t unbolting anything down there anyhow. I would swap out everything and have an exhaust shop do the final weld.

That sounds plausible except you might want to put in a dowpipe to mate to the '97 exhaust.

Remember that custom SS exhaust I had? (page 15 of The Exhaust Thread), the movie of it is here:

https://www.youtube.com/watch?v=0ClrUs29qS0

I later switched that out for the '04 PAU exhaust -- It sounded great but I got tired of it on long (100 mi) highway trips. A friend of mine bought it from me and we put that SS exhaust on his '96 (instead of me hangin it on the wall in my Man Cave). He had a local welder cut the SS exhuast at the flange before the cat, and weld a extension/downpipe (also in T304) to mate up to the '96 exhaust manifold. We were going to just get a downpipe to mate but the welder had the stuff around to do the splice for short money.

And I took the old cat and turned it in for $$ when I bought the '04 PAU exhaust, which was "custom" made for me by GM RPO. They did a very nice job, too. It *just* fits the Riviera.

Anyway... I guess there's several ways to do this; have to make a guess as to which works for you, get it done, and move on.

By the way - the used cat is worth $50 to $100 even if not working - you may be able to trade it in at a GM dealer, parts store or exhaust shop for the cash. Your problem will be that you ought to deal with someone who knows you because a counterperson will likely accept the cat but not pay you, and pocket the scrap value later. You may have to ask around to find someone who will pay you for the thing, might turn out to be a junkyard...

Albertj