Broken Exh Manifold Bolts

[alvocado]

My '02 Yukon Denali has been experiencing some loud ticking at low speeds so I inspected the exhaust manifolds for a possible leak. I found the outer two bolt heads have broken off on the drivers side. The forward bolt stem is in tact so I can get a vice grip on it to remove it from the head. The issue is with the rear most bolt closest to the firewall. I used a small mirror to examine the bolt hole and it looks like the bolt snapped off close the base of the manifold, close to the mounting surface of the head. I really don't want to pull the head off to replace the manifold. Does anyone have advice on how to remove the broken bolt considering there is very tight clearance near the firewall (so unlikely a drill will be possible?) I'm not sure if I can get enough torque and speed on an easy out bit using a hand drill or tap wrench. I'm always game for an excuse to buy a new tool.

 

Separately, I found both valve cover gaskets to be leaking so I'll plan to replace the gaskets at the same time. I'd like to clean the top of the engine before pulling the covers since it's caked with dirt but I've seen quite a few issues with water damaging the knock sensors after spraying the engine. Any advice on a safe way to get the crud removed from the fuel rail area safely?

[brianf60]

The best way to remove a broken exhaust stud. Take a small carbide bit and grind the bolt a little to make it shiney and clean. Take a washer that is just smaller (inside diamiter) then the bolt. Coat the head surrounding the stud with some antispatter paste (found at welding supply store...) Use a mig welder to weld the washer to the broken stud. Make sure you make the weld good and hot so it will stick well, but don't overdo it and be careful not to weld to the head. When that cools weld a nut to the washer, coat it in some good quailty perentrating oil,let it soak. Now remove the stud with a wrench. Make sure to start by tightening first (this helps break up the rust)

Easy as that. I do about one a month. If that doesn't work the heads got to come off. (very rarely do I have to do that) just take your time.

[alvocado]

Good suggestion. A buddy of mine was a welder for GM so I may be able to recruit him for some mobile welding in my garage.

[jtramsey]

I had two break on a 99 k2500 6.0.I took the exhaust manifold completely off and was able to get the vise grips on them after soaking them with liquid wrench.They came on out easy.

[jro909]

had to remove my manifolds and drill the bolts out...

[shawn57nomad]

If you have a right angle drill and a short enough bit you can center punch the stud, drill it, and use an easy-out to remove it, we do it that way at my little brother's shop and it works good....Oh btw he bought a special tool from Snap-On that is specially designed for exhaust bolt removal on any exthaust bolt, ANY! Just remember that if you have aluminum heads and weld on the steel bolt the heat will dissipate and possible ruin the temper of the area around the bolt hole making it brittle and possibly pulling the threads when you remove it if it is still hot, bad bad, replaced several on customers of my brother's that thought they could weld to what was left and not harm the head(s). My 2 cents. If I remember correctly GM has a recall on this problem and the dealership will fix free of charge, not real sure on the details though.

Just follow the 6 "P's" and all will go well : PROPER PLANNING PREVENTS PISS POOR PERFORMANCE

[alvocado]

I hadn't thought of a right angle drill but that would work great. Recall coverage is out with 141k miles.

[brianf60]

With aluminium heads (this even works on steel), get the bolt red hot then cool it VERY quickly with water. This will shrink the bolt a tiny amount. The bolt will come out no problem.

[MYZ-71]

I`ve removed a couple on my 01, I use a stick welder with a 1/16th stainless steel rod welding the washed and a nut or bolt, the stainless rods are very hard and won`t twist off easily, I`ve been putting off doing the same bolt on mine as it`s the hardest to get at, passenger side wasn`t bad with tire and inner fender removed.

[alvocado]

Assuming there are no visible cracks in the manifold, is it fine to simply replace the bolts and gasket? I don't see evidence of a significant leak which would cause warping so I'm hoping I can simply swap out the bolts. I'll plan to pick up extra exhaust flange bolts and and o-ring assuming there's a high chance they'll snap off during removal.

[alvocado]

I knew I was in for a treat with 8 yr old rusted bolts but I'm not off to a good start getting the exhaust flange nuts off. I soaked them all day in penetrating fluid and have only been able to break the forward most nut loose using a 3ft iron pipe for leverage. I tried every combination of extension, ratchet, etc. and can not find a way to get a socket squarely on the rear most nut since the exhaust pipe is in the way. For those that have managed to get the flange loose, any advice would be greatly appreciated.

 

I also confirmed the broken manifold bolt near the firewall is broken off below the face of the head so that will be stage two of this fun adventure once I get the manifold out. Fortunately, the 4 bolts with heads in tact came out without breaking and I have a good piece of bolt stem to grab on the second broken bolt.

[alvocado]

I made some progress since last night thanks to a Craftsman bolt extractor kit. It worked like a charm to grab the exhaust flange nuts and break them loose.

 

The two broken exhaust manifold bolts are a different story. The first bolt has nearly all of the shaft but I'm not able to get the easy out bit to grab hold. I tried drilling a pilot hole with a tungsten bit but I haven't found any bit capable of drilling into the hardened steel. Any advice?

[alvocado]

I've determined there is no way to remove this broken stud with the head installed. There isn't enough clearance for my right angle drill even with a very short bit installed. I was able to get the forward-most stud out with a larger pair of vice grips and two days of soaking with PB Blaster.

 

Next step: removing the head so I can have a machine shop extract the stud.

[markw8]

I had mine done on my 2000 before going to Alaska in 08. When I got home that back one was broke again. I think there is too much heat concentrated there. 15% grade for 3+ miles will do that. Opened the hood a let it run about 5 min. after stopping at the top.

 

Mark

[alvocado]

The replacement manifold bolts from the dealer were larger than the factory bolts so it appears they have been redesigned, hopefully preventing the issue from recurring.

 

Is there anything I should do as preventative maintenance while I have the head pulled? If I'm going through the effort, I'd like to make sure I catch anything that should be replaced with 141k on the engine.