But, the patient is being good. It's the doctor who needs to recover! The operation isn't quite finished yet, and my sore knees and back aren't looking forward to getting back under there.
But although it was time consuming, it was fairly successful.
Just to give you some background, Sherman's engine is a 1995 Chevrolet 7.4 litre (454 cubic inch) on a P30 chassis. These engines have a very common problem where the exhaust manifold gets too hot and when it expands, it breaks the studs that hold it in place. The biggest part of the problem is that the broken piece of the stud remains in the engine head and can be very difficult to remove.
There are eight studs, and it's common that the two rear studs on the right hand side will break. That's exactly what had happened to Sherman. It's actually been like that for quite some time, but the exhaust leak noise due to the broken studs has been steadily getting worse, and I finally decided to do something about it.
I bought new stainless steel studs, as well as new studs and hardware for where the manifold bolts on to the exhaust pipe. Also, a bolt extractor kit and some high quality drill bits to drill out the old broken studs.
First, I had to get the right side up in the air, supported safely, and the wheel removed.
Next was to remove this air flow shield so that we could access the manifold.
See the hole at the end of the manifold? There's supposed to be a stud and nut holding that together. Worse still, the next one over is broken too!
The shield came out fairly easily. 4 bolts and two clips.
Now, we have access to the manifold.
I removed the spark plug wires from the plugs on that side and tied them up out of the way. Then, I heated the remaining nuts that hold on the spark plug heat shields and sprayed water on them to cool them off right away. I used the impact gun to remove them, and they came off easier than I thought they would. I then did the same thing to the remaining nuts that hold the manifold on. Each one of them came right out! I was impressed!
Only one problem.
The oil dipstick tube runs to the oil pan through the manifold. It gets awfully hot in that location, and I noticed that it was cracked. The tube had to be removed in order to remove the manifold, and sure enough it broke. I haven't yet figured out what I'm going to do about that.
Cracked dipstick tube.
Then, I had to heat and remove the three nuts holding the exhaust manifold to the collector pipe. Again, they came off fairly easily!
With a little bit of maneuvering, I removed the manifold.
Next, it was time to try and remove the broken studs from the head. I hit the middle of the broken stud with a center punch, and drilled a 1/8 hole. I couldn't get the drill centered though because the frame rail was in the way and the bit went in crooked. And I simply couldn't get the stud out. Very frustrating, and I had read where this might happen.
After drilling and trying various sizes of extractors, I had made a bit of a mess of it.
Hmm. What do do?
I've learned before that when something like this gives you a problem, you just walk away from it for a while. I decided to try the other broken stud and see if I had any better luck.
I managed to get the hole drilled perfectly in the center, and I drilled right through the stud. Used the 1/8th extractor, and it came right out!
The extractor walked that broken stud right out of the head.
Why couldn't the first one have been that easy?!
So, I went back to the first one and ended up drilling it out with a bigger bit. Then, I used a 3/8" bit from a tap and die set to re-thread the hole. I threaded a new stud into the hole, and I think it's going to work. The stud is slightly crooked because I couldn't drill it straight on. I don't expect this to be a problem because the hole at that end of the manifold is quite enlarged and there should be room for it go on.
By now, it was 5:00pm and I had had enough. Glad I'm not paying someone $120 an hour to do this!
Back at it this morning to put everything back together.
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