Im about to repair the four exhaust leaks on my truck and i need some advise.

The drivers side header seems to be MASSIVELY leaking exhaust from two of the exhaust ports, and the passenger side seems to be leaking from one of its exhaust ports as well. There is also a leak where the muffer is connected too.

To test it, i hooked up a shop vac to the exhaust pipe, and turned the vacuum on to exhaust mode. Sure enough there was plenty of air rushing out of the gaskets. The air pressure escaping felt like a blow drier. There was even evidence of black soot from the exhaust gasses after i removed the header heat shields. I even sprayed the leaks with soapy water to help locate all the leaks.

I was able to tighten one of the header bolts, and it helped with the leaking a little bit, but the leaks are still present. Man, tightening just one bolt, really restored some lost power in acceleration on my truck!

My question is... In worst case scenario, how much work is involved if some of the header bolts are snapped and how bad is it to try to remove them?
Im assuming at this point the gaskets will certainly need replacing but im not sure about the header bolts. If the bolts are ok, should i replace them anyway with new ones? FYI, my truck is a early 2006 V8 st dakota.

 

It can be rough removing a broken bolt or stud under circumstances where you have a lot of working room, but doing so around the exhaust manifolds can be really painful - even more so if it was a "self inflicted injury" where you broke it by trying to tighten it. If it breaks after it's turned (even slightly), this can be relatively easy to remove. If it breaks without moving, this can be very difficult because it was probably seized.

From your description, it sounds like you have issues with the header gaskets or the header surface. I would seriously consider completely removing both headers & re-install them properly with new gaskets AND new bolts/studs (from previous vehicles, I've found that there's usually something "odd" about these bolts making the dealership the only place you can get duplicates in strength and shape). When you remove the headers, check the flange area to ensure it's perfectly flat and there are no weld lumps keeping the header from seating flat (I check them with a straight edge and then fit them against the block to see how flat they sit). Often, the manufacturer does the quickest assembly possible to save money and welds the tubes to the flange on the inside flange surface only where it's flat and a lot easier to weld than the outside of the flange surface where you have all the other pipes in the way. The almost never smooth the weld to allow for better gas flow. Once you get the flange to sit flat against the block, then clean all the threads, add the gasket, pull the header tight to the block using the correct bolt sequence and the correct torque. With the headers off, you should be able to fix the header-to-muffler (should be the cat before the muffler) leak easily with a different clamp, weld, etc. (your choice). After running this for a while, you'll need to re-torque the bolts, again, in the proper sequence. If you need to pull the bolts/nuts tighter than the specified torque, you should first look up what the maximum torque would be for that fastener, and then over-do all of them by the same amount.

 

Im not positive if any of the bolts are snapped yet. I dont believe that I snapped the bolt that i tightened, i was just wondering what would be required in case if i find that one of the bolts has failed. As i was researching the issue, it just seemed that many of the older 3rd gen dakotas have had their header bolts mysteriously snap (by themselves?) prematurely without actually having any work done on them or they break when being removed.

Either way, ill just order new bolts with the gaskets. Thanks for the tip about the flange surface, ill make sure to inspect it before I reinstall it.

 

There are a number of ways to remove snapped bolts from a block, the worst way would be to try to drill out the broken piece completely - it's almost impossible to get the exact center of the broken bolt for a pilot hole, so any drill-out is going to offset the original hole. I tend to start with drilling a hole to see if an easy-out will remove the piece - this works well with a bolt that has turned at least a bit, but for a seized bolt, you need to be careful not to snap the easy-out. Hard steel tools stuck into the broken bolts really complicate the removal. If I can't get the broken piece to move with reasonable force, I usually end up welding a washer, then a nut to the stuck piece. This process has never failed for me, to do it, you need to remember to fully disconnect the ALL control units (PCM plus whatever else is on the vehicle) as well as the battery. Generally, disconnecting the battery is adequate, but I prefer to go the extra mile to make sure that no spike gets into the controller circuitry.

Exhaust bolts go through a lot of stress, but any that have been removed and re-installed more than once and torqued without measurement are really suspect to failure. For high stress, high torque bolts that I'm not sure of, I replace them instead of creating myself extra work in practicing broken bolt removal.

When you decide to remove the old bolts, there's still a chance for seized bolts to break. I try to minimize this by soaking the threads in penetrating oil for a few days before I try to remove them. When you're trying to turn each old bolt, try to feel for whether the bolt might be seized - using a breaker bar will usually ensure getting a broken bolt. If you can fit some extenders to the bolts through the wheel well, I'd tend to use a good impact gun, the hammering is a lot easier on the fastener than a steady rotational force.

When putting the headers back on, a flat flange & flat mounting area around the ports is essential - the gasket is there to make up for small differences. I've found that cheap headers often mean warped flanges, and this means exhaust leaks. Some bent or warped flanges can be straightened easily, while others need more surgery - just make sure the flange is clamped perfectly flat for the re-weld & let it cool while clamped.

 

I have had this same issue three times in the past four years since I purchased my used '06 Dakota. Each time I took it to a local muffler shop who extracted the broken bolt for $100. Each bolt held its own until another bolt gave way. After the third time I purchased a pair of SS Gibson headers. Havent had a issue yet.