Smog pump removal questions...

[GroovieGhoulie]

What started as a simple muffler replacement turned into a "well, as long as I'm down here..." job and now I'm removing the smog pump and air injector hardware. Mission Creep is a b*tch...

A couple of quick questions about the job. The search function here turned up a LOT of answers, but a few things about the under-tin half of the job are flummoxing me.

1. What's the best tool to use to get the 13mm nuts off the exhaust studs, and the allen-head bolts? There is no room to work there. Maybe a dog-leg box-end wrench for the nuts? I've got the nuts soaked in penetrating oil, along with the bolts for the crossover, so I'm planning to tackle it tomorrow, or the next day depending on how long it needs to soak.

2. There was a 1/4" vacuum line plugged into the top of the "splitter" that went from the pump to the spider, and it appears to head under the airbox, somewhere around the fuel head. What does this do, and what should I do with it? Just plug and stow it? I figure it's unnecessary at this point.

All the above-the-tin work went easy, with the pump and air line coming right off. (After I pulled the intercooler and an intake pipe elbow). Now I just need to pull the spider and plug the heads. I'm not looking forward to dropping that heat exchanger, but it's gotta happen.

Are the only real benefits from this job that the car loses about 20 pounds from the rear, and the heads run a little cooler? Anything else?

[A930Rocket]

I don't think there is one or two tools that do the job. I find myself using an assortment of sockets (1/4 & 3/8), wrenches (long and short), u-joints, and maybe the special exhaust wrench offered by pelican.

I've since replaced all the nuts with a common copper nut to make it easy to remove and tighten. Those allen nuts are terrible.

Plug the vacuum line at the source.

[NathanUK]

I used a nut splitter to get the nuts off the studs. I tried to undo two the normal way and snapped the studs...

[GroovieGhoulie]

Well, now more questions:

The nut removal went well, I suppose. I was VERY worried about snapping off the studs, but none snapped off. In fact, the nuts were so well welded onto the studs from age, heat and rust, that the entire stud backed out. All six. Perfectly.

So now, the question is: can I re-use the studs with the nuts "welded" in place as de-facto "bolts" now? I don't think they're stretch studs or anything, so when I put it all back together, it should be no problem, right? I'll just make sure that I thread them into the head properly and don't over-torque so I don't strip the softer alloy head.

And yes, I used liberal amounts of penetrating oil and heat, but the studs still came out with the nuts. I'm just glad I didn't snap any off. I think I can work with them like this.

Thoughts?

[A930Rocket]

I would order some better studs and nuts from EBS, Supertec (I think it is) or may Pelican has them. You got away with it once....

[GroovieGhoulie]

Good call.

I'm seeing "non-corrosive hardware" offered by Pelican, which is appealing, despite the price, but the OEM 930 studs are 50mm and the non-corrosive kit ones are 22mm.

I've sent them a question to see if they will work. If not, I'll get OEM ones.

[A930Rocket]

The difference probably depends on whether you have thick of thin exhaust flanges. Got a picture?

The non-corrosive stud would be a good investment.

[GroovieGhoulie]

I'll get pics tomorrow. From memory, the flange looked maybe 10-12mm thick. Closer to 12mm I think.

[lucittm]

The studs that Porsche uses are harder than what you would get at an auto parts store but I don't have any data on an actual hardness number.

The 22mm studs are for the thin exhaust flanges, you need the longer studs for the thicker flanges on your car.

I used ARP studs and nuts P/N 771-1004 and P/N 400-8310. They are way expensive but I never have to worry about them again.

A930Rocket uses copper nuts and that is a great idea if your studs are in good shape. I think at some point the dissimilar metals of the head/stud junction will eventually cause corrosion or seizure issues. I would not reuse what you have unless you can get the nuts off the studs. Then the studs can be reused depending on the condition, if you really must.

Mark

[GroovieGhoulie]

I checked the ARP part number 771-1004 and it's a bolt.

I found their studs, and they are all M8x1.25mm pitch. That should be the same as the OEM pitch, so as long as I got the 2" ARP (50.8mm v. OEM 50mm), I should be in business, correct?

[A930Rocket]

1.25 sound right, but take your old stud to a Lowes, HD, ir hardware store to match a nut up to it to be sure.

The difference in length is negligible.

[lucittm]

Sorry, I gave you the P/N for the exhaust pipe flange bolts. Here are the correct P/N:
400-8005 and 400-8015. The first number is a four-pack and the second number is an eight-pack. The studs are listed as M8 x 1.25mm and 57mm long because they count the unthreaded rounded nose in the overall length. They come complete with thick washers and nuts.

Thanks,
Mark

[A930Rocket]

http://www.arp-bolts.com/Catalog/Catalog.JPG/ARPCatalog_0075.jpg

[GroovieGhoulie]

NICE!!!

I'm gonna get a set of them on order. It looks like SUCH a better solution than the OEM units. If I ever need to do exhaust work again, it'll be no-issue.