Broken Exhaust Manifold Stud

Every once in a while I think to myself, "I should have left well enough alone." Last night was one of those times. I decided to change the oil, do a minor tune up and adjustment, and tighten a few bolts. It was tightening the few bolts that got me into trouble. I noticed a slight exhaust leak sound coming from the left side exhaust manifold and traced the sound to the joint at the head. I decided to tighten the nuts that hold the manifold onto the studs. Three of the four nuts tightened slightly, but as I tightened the fourth one, the stud broke off just below the level of the manifold.

Arghhhhh, and a few other choice words popped into my head. This was immediately followed by, "I should have left well enough alone."

I removed the manifold and saw that there was about an inch of stud sticking out of the head. Perhaps this was enough to grasp with a vice grip to turn the stud out. Unfortunately, I could not get the vice grip on the stud without first removing the number four cylinder push rod tubes, which meant the push rods had to come out, which meant the valve rockers had to come out, which meant the valve cover and EGR filter had to be removed. I also had to remove the warm air duct that comes from the heater valve (California model only).

Once everything was removed, I gripped the stud with the vice grips. The stud would not budge. I worked the stud numerous ways over the next two hours, even heating the stud boss with a torch to expand the aluminum. Nothing worked. I cried and gave up for the evening. Through the night, I formulated a plan to cut the stud off at the head, drill it out, and rethread the head with a tap. Fortunately, I had a spare stud. The stud is called a step stud. The head end is 9mm x 1.25mm thread pitch. The nut end is 8mm x 1.25mm thread pitch. Very hard to find. I wandered off into dream land thinking about the bus sitting unusable in the garage for the next few years before I got up the energy to remove the engine once again

Skip to this morning...Woke up, got out of bed, dragged a comb across my head. Sorry, I know that line is already taken. Plus, my hair is hi and tight I don't really need a comb. Anyway, I spend four hours doing all that I had dreamt of through the night. I drilled, and drilled, and drilled, and drilled some more. Slowly, so as to go straight and not too far. Too far would mean drilling through the valve guide, a bad and costly mistake. This drilling required serious eye protection since I was drilling up while laying on the ground underneath. One tiny piece of metal in the eye and it would mean a day wasted in the emergency room.

Once the stud was drilled, I cut it off flush with the head. There was no turning back now. Everything appear centered and straight, which was no small feat. It took about an hour just to drill the stud and leave an almost paper thin outer shell. I retrieved a 9mm x 1.25mm tap and had to fashion a long extension bar to work it into the head. The new threads were in soon and I was able to thread the new stud into the hole. Whew! That required a lot of slow patience and careful work.

Once the new stud was in, it was just a matter of re-assembling everything back together. While I was there, I re-adjusted the hydraulic valves all around to two turns past contact. Once everything was back together I fired it up and the engine came to life, quiet, smooth, and seemingly powerful. No more exhaust leaks.

In the end, this was probably one of the most frustrating times I have experienced while working on the bus, and I thought to myself over and over that I should have left it alone. But, in the end the exhaust leak was repaired and everything was put together the right way. I experienced extreme sadness, pain (cuts, burns from the torch and hot pieces, and muscle aches), relief and great joy. I guess that is what VW bus ownership is all about. The vehicle brings forth all emotions.

Happy Bus Motoring

Ron (o v o)