netmazk

Several weeks ago I purchased a set of headers off of ebay (you know the brand...), packaged with hi-flow cats and an X-pipe. This was the next step for my silver 2007 MN6 after I put on a SLP Loudmouth II axle-back exhaust shortly after I purchased the car.

I spent about 10-12 hours on the install last week, spread across 3 nights working after work until it got dark, and some finish-up work this past Saturday. Overall, at first glance, the headers and X-pipe were good quality. Solid welds, clean, etc. I ran into a few problems:

• Each cat attaches to the X-pipe with another 10" or so long tube which has a rear O2 sensor bung. One of the pipes would not fit into the cat side at all. It took me probably 45 minutes of working the edges of both sides to get them to fit together properly. OK... no big deal, problem solved.
• While bolting up the headers, I managed to break off not one, but two of the header bolts. The first one is the terrible not-so-reachable bolt near the driver's side firewall. My heart sunk, but I figured it was just bad luck with these 5-year old 40kmi bolts. I continued on the next side and managed to do the same thing with one of the middle bolts. Looking back, my torque wrench is probably garbage. I had it set on 10 ft/lbs. the whole time, and never got any of the bolts to torque. I didn't doubt the wrench at first, since I had used it a few weeks ago to torque a few things to 40 ft/lbs. just fine. Both bolts appear to have enough thread hanging off of the heads that they seem to have broken flush with the heads. To cut to the chase, I finished the install and I can't find any leaks between the headers and the heads.
• The cats have 4-bolt loose flanges that bolt up to the header collectors, and use a graphite donut gasket. What a pain in the ***. First off, another fitment issue. With everything else hooked up and loose, the cats were too close together, almost angled. The driver-side hooked right up to the header, but the passenger side really wasn't that close. I managed to hold them apart enough to get the bolts in and wrenched them together the rest of the way while holding them in the right position. However, I think they're pulling themselves together, and pulling the driver side cat off of the collector and breaking the seal at the gasket. To make matters worse, with the 4-bolt flanges, there isn't really enough clearance to tighten them equally. It's almost as if I have get them fairly equal all around, tighten a side of two, spin the flange, and then get the bottom set of bolts tight. Couple this with the terrible spring retainers, and I think they are probably just loosening themselves up.

I tightened everything up Saturday morning and drove around a good bit during the day. Everything sounds GREAT, but there's an obvious tick coming from the collector/cat area. It's very noticeable with the windows up, and to the side of the car, but doesn't sound like it's coming from the engine bay when the hood is up.

So, overall, I'm looking for some forum advice on what to do next. As far as I see it, I have two routes:

1. Ignore the header bolts for now (might swap heads and cam in the future/next summer), get some lock washers & nuts for the cats, and re-tighten everything with extra emphasis on getting the cats lined up properly with the collectors in the first place. Maybe I can use something to bend them out and actually stay in the right position?
2. Take it to a shop, have them extract the broken bolts, replace all of the header bolts, and have them look over the whole system for leaks. However, I have no idea what I'm looking at here in terms of cost or hours of labor, nor do I know of any reputable vette mechanics in my area (Pittsburgh).

What do you guys think? Does anyone have any recommendations for mechanics within Pittsburgh or less than two hours away? Do you think a shop is going to be able to give me an accurate estimate?

94ltz

You can get stage 8 locking header bolts for $35, if they broke flush with the header flange a good stud extractor tool can get them out or even vice grips. I would take it to an exhaust shop and have them possibly make a couple cuts and welds to make those cats go in the right direction.

black.z51.c6

if its a stick shift make sure the slave cylinder hose is not touching the headers as it will melt and cost 1600 to replace. it only has to be a 1/4 inch away.

black.z51.c6

the torque wrench probably is fine but with the bolts heating up and cooling down thousands of times it burns the carbon out of the steel and anneals the bolts so they are soft.

netmazk

It's a stick and I've made sure everything is clear of the headers. I routed the O2 wires as far as I could as well.

Unfortunately, the bolts seem to have broken off flush with the heads, not the header flanges (I haven't taken the headers back off to check), so I don't think vice grips, etc. are going to be an option for me. I could maybe get a drill and extractor on the passenger side bolt, but I don't see any way for me to get near the driver's side firewall bolt easily.

truckplay

you will probably have to pull the brake master and booster. you got yourself in a pickle . don't drive it with an exhaust leak at the head, you will damage the exhaust valve.

VET4LES

I think you should let the pro's take care of all the issues. There's an old saying that the "cheap comes out expensive".

SUB VETTE

I'd take it to a muffler shop and get those broken bolts out. Ask around to find a good shop. The ticking you are hearing is probably an exhaust leak at the header gasket. When I did my headers I didn't chance using the old bolts but bought some ARP studs instead. The shop can also get things lined up properly using torch heat if needed. Get some new ARP bolts or studs for the shop to use, and replace them all.

Purple92

I really wouldn't recommend driving the car around with a bolt on each side missing, eventually - the gasket will start leaking, then the leak will get worse, and worse.... Worst case is that the sealing surface on the head can get damaged...

If you were going to try to get the bolt out yourself, I would STRONGLY suggest getting a couple of left hand drill bits (no - I'm not kidding - these things do exist). You drill in reverse - so instead of trying to twist the broken bolt further in - the drilling tends to help remove the bolt. I've never had much luck with E-Z outs, so if you try one, don't put enough torque on it that it snaps - the E-Z Outs are as hard or harder than the drill bits, so if you break the E-Z out off - it moves from a PITA job to a nightmare.

The good news is that once the head of the bolt is no longer there - the bolt itself isn't in tension, so the amount of torque required to remove it is substantially reduced.

Once you get a decent hole in the old bolt - you can try one of the broken bolt remover tools - or you can just keep going, and drill the bolt out entirely - then use a Heli-Coil to repair the thread - a decent auto machine shop will have these - or you can order them.

If you choose to take it to a pro - they will probably need to remove the header before they drill the bolt out, and the kind of shop you want to do the work will do the drilling very carefully - making sure they drill straight into the bolt. It's probably not going to be inexpensive...

GOOD LUCK !!!

irok

sounds like many operator errors to me.the donuts and spring retainers work great and can be easily reached with an extension from between the collectors.the spring tensioners only need to be a little better than hand tight. go to any muffler shop in your area . they will be able to install properly for you.

erikszr1