2000 C4 Full Exaust Replacement

Hi All, Brought my 2000 C4 to my mechanic to look at cat codes. They did a full review of the exhaust system and said it really needs to be replaced and is very rusted and leaks. They also explained the bolts which attached the exhaust headers to the engine are totally rusted out and its very likely they will have to be drilled out by a machine shop when being replaced. All in all, the full replacement was quoted at possibly north of 8k depending on if they can get the header bolts out or not without having to remove the engine. Has anyone else gone through this? Thanks

Take it to another shop (ie: get a second opinion). It's possible that they're correct, but more likely they're just jacking you

dporto - thanks for your reply and suggestion. My mechanic seems like a trustworthy guy and sounds like they have seen this issue before, but your right. For something this expensive I'd be dumb not to get a second opinion.

There's an awful lot of stainless steel in these exhaust systems. Generally speaking, the main things that rust are the fasteners (use stainless when re-building). The O2 sensors also go bad and they're way more affordable than new cats... As an aside, the first time I took my exhaust system apart I was freaking out because I thought everything was going to break. All the header bolts came out of the heads with no problems, which was a major plus! The worst bolts were the long skinny ones that go through the muffler brackets...Most of the bracket hardware broke or had to be cut off, but was replaced with stainless and copious amounts of high temp anti-seize... Good Luck

Look up stomski racing they have a jig for drilling out the header bolts. A lot cheaper then a machine shop.

Not sure if this is available in US but when I was struggling with that alternator bolt (all youtube etc "sources" are telling to hit that with a sledgehammer) I used CRC's Rost Flash Pro - basically it chemically freezes the object and I was able to open that almost easily. There's this CRC Freeze Off on Amazon so I would probably try with something like that first.

Here is the link for the Stomski Racing kit to remove and replace the header bolts. Boxster/996/997 Exhaust Bolt Repair Kit – STOMSKI RACING LC While it is $342 that is a lot less than a machine shop. To use a machine shop you have to take the head off the engine which means you are dropping the engine and will need new bolts, gaskets and more. Hell it would be less to buy the tool and give it to your shop. I have broken off several rusted header bolts and have been able to get all but one of them out without any special tools. And as said before use stainless steel bolts for replacements..

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Excellent suggestion. Thank you! Is lifting and replacing the bolts something that could be done by an amateur lifting the car in my driveway? I have basic skills like doing oil changes, breaks etc. My thoughts are I could replace the bolts that are corroded and let the mechanic do the full exhaust replacement.

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Yes u can do it in the driveway but u need it high enough to get the drill under it and leverage. I would sell my stomski tool as i have swaped to a different motor and i cant use it anymore.

8k for full exhaust? Even needing to drill out the bolts seems like a lot. The hardware on these are known to get really bad, mine was awful but the oem hardware isn't that expensive and you can get non oem exhaust parts for relatively cheap.

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My 2-cents, I think the header bolts are the hard part. If you feel up to drilling out header bolts, then the rest is easier, just do it all. I've had mufflers off to replace coils, replaced cats, and replaced exhaust tips. Only part I haven't done is headers, because that's the hard part.

I used PB blaster daily on the header bolts of my car for a week,,, then used a MAP torch to heat the bolt heads up, got all but 1 out , and it broke at the base so still had 1/4 inch sticking out of the head.. Just put torque on the bolt and be patient,, firm, not crazy,, ,,, tap on the wrench with a brass hammer directly over wrench head. The one I broke I got in a hurry on.. All the rest of the bolts that directly touch exhaust pipe will likely need replaced. All the ones that held the brackets on came out easy.. Other than being a royal pain in the butt to get at..

It�s not uncommon for a couple header bolts to break. They are 20 years old and have been through a hellish number of heat cycles. That�s the hardest part for sure� I would not spend $8k on an exhaust. Rather, go aftermarket full stainless, get brand new mufflers, new cats, all 4 sensors for probably under half the $8k, including all labor. And chances are, the aftermarket exhaust sounds better and weighs a lot less. The stock mufflers are quite heavy.