How much should exhaust install cost?

[David4315]

Can anyone give me a rough idea how much it should cost to install headers, mufflers and cats. I just purchased the AWE set up and have no idea if should cost $500 or $1500 to install. I know it is pretty straight forward and if I had the time and a lift I think it would be fun to do myself - no joy there... Any rough idea is useful. I have a guy who certainly seems very honest and does pleanty of high end work (much nicer than my 997) but always good not to be flying blind. Thanks.

[1schoir]

Can anyone give me a rough idea how much it should cost to install headers, mufflers and cats. I just purchased the AWE set up and have no idea if should cost $500 or $1500 to install. I know it is pretty straight forward and if I had the time and a lift I think it would be fun to do myself - no joy there... Any rough idea is useful. I have a guy who certainly seems very honest and does pleanty of high end work (much nicer than my 997) but always good not to be flying blind. Thanks.

The biggest variable in the labor in installing exhaust systems is the degree of difficulty encountered in unbolting the stock exhaust manifolds from the cylinder heads. If any one of those 12 bolts is "frozen" in the aluminum head and snaps off during the attempt at removing it, you are looking at a major change in the amount of time it will take to install your new exhaust parts. Since it looks like you have a 2006, unless you are in a location where lots of salt is used on the roads for snow and ice conditions, your fasteners stand a good chance of not being completely frozen in there. If they do snap off, it can be quite a task to remove the old bolt remains without damaging the threads in the aluminum head.

If the guy is as experienced as you say, have him put the car up on a lift and give you his assessment of the conditions of those twelve bolts. For all of the remaining fasteners between the headers and the cats and the cats and the mufflers, it's pretty predictable how much time it would take to undo those, including whether any (or all) will have to be cut off.

He should be able to give you a fair prediction of the hours that he claims it will take to remove all the old parts. Installation, with all new fasteners, is very predictable in terms of the time required.

From having done it myself on a '97 Boxster, three hours of labor for a total replacement should be sufficient if the car is up on a lift, assuming that none of the aforementioned manifold bolts snap off. Some of mine did (4 of them!), and that was a completely different story. :eek:

Regards, Maurice.

[David4315]

That makes sense. I had not really even thought of the possible damage to the heads. the car only has 30,000 miles on it but this kind of thing is a roll of the dice.

[phillipj]

I changed my headers myself on my 997 on ramps. Super easy. Took my an hour.. You should have no problems with your header bolts with only 30k on your car. I agree that 3 hours labor sounds about right.. Easy job if you want to do it yourself. But I can also understand having someone else do the labor

[racerken]

Can anyone give me a rough idea how much it should cost to install headers, mufflers and cats. I just purchased the AWE set up and have no idea if should cost $500 or $1500 to install. I know it is pretty straight forward and if I had the time and a lift I think it would be fun to do myself - no joy there... Any rough idea is useful. I have a guy who certainly seems very honest and does pleanty of high end work (much nicer than my 997) but always good not to be flying blind. Thanks.

The biggest variable in the labor in installing exhaust systems is the degree of difficulty encountered in unbolting the stock exhaust manifolds from the cylinder heads. If any one of those 12 bolts is "frozen" in the aluminum head and snaps off during the attempt at removing it, you are looking at a major change in the amount of time it will take to install your new exhaust parts. Since it looks like you have a 2006, unless you are in a location where lots of salt is used on the roads for snow and ice conditions, your fasteners stand a good chance of not being completely frozen in there. If they do snap off, it can be quite a task to remove the old bolt remains without damaging the threads in the aluminum head.

If the guy is as experienced as you say, have him put the car up on a lift and give you his assessment of the conditions of those twelve bolts. For all of the remaining fasteners between the headers and the cats and the cats and the mufflers, it's pretty predictable how much time it would take to undo those, including whether any (or all) will have to be cut off.

He should be able to give you a fair prediction of the hours that he claims it will take to remove all the old parts. Installation, with all new fasteners, is very predictable in terms of the time required.

From having done it myself on a '97 Boxster, three hours of labor for a total replacement should be sufficient if the car is up on a lift, assuming that none of the aforementioned manifold bolts snap off. Some of mine did (4 of them!), and that was a completely different story. :eek:

Regards, Maurice.

Hi Maurice,

I have a 08 997 with 38k miles and I drive it every day in Michigan where the roads are salted. I'm replacing all the rusted bolts and I'm wondering if I should attempt the exhaust bolt replacement. I feel that if I swap bolts now and it's successful, any downstream removal will be an easy task.

What do you think?

When your Boxster bolts broke off there they in this shape?

Also, how did you extract the bolts? EZ-out plus a rig?

the alternative is that I do nothing and just worry about it 100k miles later during engine rebuild.

Thanks,

Ken

[Mijostyn]

Should not cost more than $300. I'm with Phillip on this one. Changing out an exhaust is usually a straight forward task on a 911. For the exhaust manifold cap screws get 18-8 stainless M8x26s. I use Wurth CU-800 antiseize on all high temp threaded fasteners. Stuff is good up to 2200 F. With the antiseize cut the torque spec from the standard 17 ftlb to 12 ftlb. I also re torque all exhaust fasteners once a year.....probably because I have nothing better to do.

[1schoir]

Hi Maurice,

I have a 08 997 with 38k miles and I drive it every day in Michigan where the roads are salted. I'm replacing all the rusted bolts and I'm wondering if I should attempt the exhaust bolt replacement. I feel that if I swap bolts now and it's successful, any downstream removal will be an easy task.

What do you think?

When your Boxster bolts broke off there they in this shape?

Also, how did you extract the bolts? EZ-out plus a rig?

the alternative is that I do nothing and just worry about it 100k miles later during engine rebuild.

Thanks,

Ken

Ken:

Seven years of driving on winter salted roads can cause a lot of corrosion on those parts and, to answer your question directly, my bolts did not look quite as rusted and toasted as those on your 997. My Boxster only had about 25K miles on it but was 12 years old at the time I did the header install.

Extracting the bolts that snapped off was quite a challenge and I did it using a variety of tools, including a torch and an electrical inductive tool that can make bolts red hot in about 15 seconds. If a bolt snapped off, I marked the center of the broken bolt in the cylinder head with a center punch and then proceeded to drill out the center of the bolt, starting with a 1/16 inch bit. I progressively increased the bit size until I could determine how close to dead center of the bolt I was. If I was off center by even a little bit, I used a dremel tool with a carbide cutter tip to hollow out the hole so that I could end up with a hole in the dead center. Once I established that, I used progressively larger size reverse drill bits until either the bolt became "unscrewed" by the action of the reverse drill bit or I ended up with just shards of the bolts still in the threads and picked those out with small picks. Using a magnet will confirm that you are only drilling out parts of the bolt and not parts of the aluminum cylinder head. You can then chase the threads with the correct size tap and some thread cutting oil.

If you want a more detailed account, you can go to PPBB.com's archives for photos and an in-depth explanation. Do a search there under my handle "Maurice on Long Island" and exhaust headers. If I find the link I'll post it here.

My solution to not having to repeat that experience was to source some proper fasteners from Maryland Metrics, which included new coated studs (not bolts), phosphor bronze lock washers and brass nuts. Now I can change out my headers in little more than an hour and don't have to worry about snapping bolts.

BTW, although I love stainless steel fasteners and use them everywhere I can, I specifically did not use stainless studs because stainless can "weld" itself to aluminum and cause an even bigger problem. Antiseize can minimize that possibility but it's not foolproof, especially where you are driving on salted roads.

Regards, Maurice.

Edited September 24, 2013 by 1schoir

[Mijostyn]

Hi Maurice,

This ones a bit of give and take. 18-8 stainless also known as type 304 is an austenitic, passive alloy which in the absence of an electrolyte will not corrode aluminum. The copper antiseize is just insurance. But, You are right in that some stainless steels like type 410 will corrode the crap out of aluminum. The cap screws are failing because of stress corrosion cracking. Plain steel is more likely to do this than 18-8. Stress corrosion cracking is not galvanic. Yes, plain steel and aluminum have almost the same anodic activity and are less likely to cause galvanic corrosion in contact with each other.

Brass, bronze and copper are much more cathodic than steel thus in the presence of an electrolyte the steel will melt away not to mention the ongoing stress corrosion cracking. You are better off using galvanized steel nuts and washers and changing them when they start corroding. The bottom line is that no matter what you use you are going to have to replace the parts once in a while, sooner better then later. No where is this more important than with exhaust headers where the difficult high temperature environment puts expensive cylinder heads at risk.

[1schoir]

Hi Maurice,

This ones a bit of give and take. 18-8 stainless also known as type 304 is an austenitic, passive alloy which in the absence of an electrolyte will not corrode aluminum. The copper antiseize is just insurance. But, You are right in that some stainless steels like type 410 will corrode the crap out of aluminum. The cap screws are failing because of stress corrosion cracking. Plain steel is more likely to do this than 18-8. Stress corrosion cracking is not galvanic. Yes, plain steel and aluminum have almost the same anodic activity and are less likely to cause galvanic corrosion in contact with each other.

Brass, bronze and copper are much more cathodic than steel thus in the presence of an electrolyte the steel will melt away not to mention the ongoing stress corrosion cracking. You are better off using galvanized steel nuts and washers and changing them when they start corroding. The bottom line is that no matter what you use you are going to have to replace the parts once in a while, sooner better then later. No where is this more important than with exhaust headers where the difficult high temperature environment puts expensive cylinder heads at risk.

Thanks for the detailed information. I think that Maryland Metrics does sell type 304 stainless metric fasteners, so that would be helpful.

Removing the factory bolts early on and replacing them with studs is by far the best approach, IMO. The factory bolts are like a ticking time bomb, and it ticks louder where they are exposed to harsh winters where roads are salted. If the bolts are removed early on and replaced with studs, it's a relatively simple matter to remove the nuts and washers (no matter what condition they are in) compared to extracting broken studs from the cylinder head.

Regards, Maurice.

[racerken]

Thanks everyone for the responses. To be honest, I'm backing down from replacing the bolts because if one snaps, I'm in a world of upside down drilling & EZ-outing. I'll deal with the removal of all 12 bolts the hard way when the engine needs an overhaul which at that point, i'll have the engine dropped, on a stand, flipped.

As for the advice on replacement as a preventative maintenance, I'm all for it, just a year late.

Just out of curiosity, does the hole go thru to the cavity of the engine block? i.e., if you drill thru, and oil is present, it will drain out the hole?

Thanks,

Ken

[Mijostyn]

The holes are blind. I also forgot something. Maurice, the headers are stainless steel, yes?? Even stainless will rust eventually particularly in high temp, salty environments. Stainless is very cathodic while plain steel is highly anodic. You never want to put the two in contact with each other which means you are basically stuck with stainless nuts washers and studs or cap screws. Studs are fine but I'm not sure where they get you. The issue of stress corrosion cracking is the same if they are torqued equally. If they break you have the same situation getting them out.

[racerken]

Hi Mijostyn, why not consider copper plated nuts for exhaust applications?

[Mijostyn]

Copper is in the middle of the galvanic chart with plain steel at the anodic end and stainless at the cathodic end. The cathode always corrodes the anode. So, if the headers are stainless the copper plating will simply corrode turning that nice shade of green eventually exposing the base metal. Copper will protect a stainless nut but corrode a plain steel nut. If the headers are plain steel the copper will accelerate corrosion on the header. Ideally you want to match anode to anode and cathode to cathode. Aluminum and plain steel are right together at the anodic end of the scale. There are special circumstances like 304 stainless which just does not like to pass electrons even though it is at the far cathodic end of the scale.

With stainless headers you could use 18-8 (18% chromium, 8% nickel) stainless studs with copper plated stainless nuts and washers. This might extend the life of the nuts a couple of weeks. You would never use copper plated studs in aluminum.

Edited September 25, 2013 by Mijostyn

[Mijostyn]

Just a follow up on the topic of Manifold bolts, studs or cap screws. I discussed the subject with the Porsche tech I use. Porsche does indeed use plain steel hardened cap screws on the exhaust manifold. Porsche's argument is that hardened steel will not gall in or corrode aluminum. Thus it is the safest fastener for the head. The cap screws they use have a beefier head than usual and they feel it should last as long as the exhaust manifold. The techs are advised to keep an eye on them and replace them if necessary. This tech soaks them in WD40 and lets them sit for 15-20 minutes. He tries to torque them out gently and if the screw does not want to come out easily he grinds the head off which leaves enough screw proud for a Snap On easy out tool to grab. He says he has never had to use a drill. He has only had to replace them on high mileage early Boxters and 996's. Not one 997 yet. Porsche does not recommend the use of antiseize with it's cap screws. The tech does not know why for sure but thinks that given heat cycling and vibration it may increase the risk of the screws loosening causing a leak. Automakers are very conservative with exhaust issues because of carbon monoxide. Let's give a big round a applause for the Lawyers!

[1schoir]

While Porsche may feel that their cap screws with the beefier head will last as long as the exhaust manifold, real world experience shows that this is simply not the case. In a '97 Boxster with only 22K miles on it, five of the cap screws were frozen stuck in the exhaust manifold in 2010. This car had not been driven much in the winter and had not been exposed to road salt, etc... Unless I am misunderstanding and Porsche means that as long as you don't have to remove the exhaust manifold you'll be okay.

IMO, the best course of action is to remove the cap screws and replace them with studs and to then use lock washers and nuts made of a material that will not rust solid onto the stud. Even if you have to ever have to cut off the nuts, you can still remove the exhaust manifold and then more easily access the remaining part of the stud using the same method as that recommended by the tech.

Regards, Maurice.

[Mijostyn]

Maurice,

You do not need winter or salt when you use plain steel in contact with stainless under high temp conditions. Porsche is banking on the cap screws lasting as long as the header which obviously and frequently does not happen. They prefer to protect the most expensive part, the head. The screws and the header are relatively cheap. They are counting on their techs to pick up the bad screws before they become a real problem. Many, however do their own work or use indies. We here are aware of the problem and will take whatever measures are needed to prevent a big headache. Thinking it over I think the best approach is to use Porsche's hardened cap screws and change them at intervals before they deteriorate to the point of breaking. Using studs and various fasteners is not going to get you anywhere. The problem is that you have an aluminum head and a stainless steel header, metals at opposite ends of the galvanic scale, in a high temperature environment, exposed to the elements. There is no way to reconcile that. Fabspeed is using composite gaskets which isolate the header from the head but to my knowledge nobody has come up with a composite cap screw.