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Dealing with snapped studs and bolts: ALL NG900, 9000, 9-3 & 9-5 models

Tools required:

  • Cobalt drill bits
  • Stud extractor set
  • Electric (or air) drill

Materials required:
replacement studs/bolts/machine screws (as required)

Estimated time required:
40+ minutes (depending on the location of the problem)

Procedure & rationale

No matter how careful you are, at some time you will encounter something like a snapped exhaust manifold stud or a bolt that has snapped in an engine block.

Broken exhaust manifold retaining studs are quite common on 4 cylinder B204/234/205 & B235 engines

Although most engineering shops can usually help, this is little good if the part in question requires major dismantling to remove. On the four cylinder petrol SAAB B2n4/2n5 series engines, snapped exhaust manifold studs are commonplace and very often the first anyone knows about the problem is when a turbocharger or cylinder head needs removing. The studs can snap in service (tell tale traces of carbon and a burned gasket give the game away), so be EXTRA careful when working on them. As a rule, whenever we carry out such a task, the studs are wire brushed and left to soak with penetrating oil but a professional workshop would use oxy-acetylene to warm the offending articles to cherry red.

The principle of removing snapped screws/bolts is fairly simple - drill a pilot hole in the centre of the snapped fastener, then screw in an extractor. As the extractor is wound in, the thread unwinds the snapped fastener.

Drill the hole as centrally as possible and SLOWLY

Golden rules

  • Don't rush - take your time with this
  • Use cobalt drill bits and drill SLOWLY (or else you will not only lose control but also wear out the drill bit faster)
  • Ensure the pilot hole is as central as possible

If the stud extractor looks as if it is not shifting the broken fastener DO NOT CARRY ON REGARDLESS! All that will happen is that the extractor will snap and as it will be made from hardened steel removing it WILL be very much harder. Instead, use a larger drill bit - this has the effect of weakening the hold of the fastener and in extreme cases, using progressively larger drill bits until only a thin layer of metal remains may be the only way to remove stubborn snapped bolts or studs.

A stud extractor, when wound into the pilot hole causes the snapped fastener to be extracted

If the snapped stud or bolt is in a particulaly tight location, use lateral thinking! We have found that an angle air drill or small format air drill has proved invaluable but for that, of course, you would need a compressor.

As a rule, when we carry out major work on engines, the exhaust manifold studs are always removed and replaced as a matter of routine. Pattern parts are available as a kit from many suppliers.

Patience rewarded; the snapped stud is removed safely

Please note that it is not necessary to remove and split the power unit to attempt this proceedure. The author decided to sieze the opportunity to capture this operation very much on the spur of the moment. Some of the cars we acquire for spares have suffered serious failures on the road and because we are passionate about recycling, as many components as possible are assessed, removed and retained/repaired for possible future use. In time, we hope to cover a wide range of repair proceedures, including stripping and rebuilding a B2n5 engine but photographing the operation is time consuming, slows progress and sometimes poor light stops play!

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