A sample of some of the jobs that we have done
V8 Mercedes Seized Intake Manifold Bolt
This job came to us after the client had removed the cylinder head to repair some bent valves caused by a timing chain that had jumped a few teeth. One of the intake manifold bolts onto the head was seized. In order to remove the manifold they had drilled the head off the bolt. The challenge on this job was that the bolt hole is at an angle to the manifold face, so alignment is crucial in order to ensure correct manifold clamping when re-installed.
Fortunately the client had not applied heat to the bolt or head whilst trying to remove it. The amount of heat that would have been required would have permanently softened the aluminium of the head, and would have resulted in the thread being torn out of the head whilst trying to remove the bolt.
The head was set up on pallet plate installed into an angle vice on the mill to ensure correct alignment and geometry. From there the other manifold bolt hole positions were all mapped out. Once that was done the exact location of the center of the broken bolt hole could be calculated.
Once calculated the center of the bolt could be drilled exactly, and the thread was removed like pulling on a coil spring. Even at this stage the bolt thread was still galvanically corroded into the head threads resulting in the need for time, patience, a measured amount of brute force, and a few subtle skills in order to remove it. You know you were right on the money for position when they come out like this.
After running a tap through the thread and checking it with a new bolt, it was found to be perfectly serviceable with no insert required.
Hyundai iLoad Van Diesel Injector Retaining Bolt
On this job space was very limited. The client was trying to replace the injector seals on a 4 cylinder diesel motor, and the socket head cap screw that retains the first injector snapped off. The client had undertaken several attempts at removing the bolt including welding nuts to it, ant trying to tap it out. When we arrived there was a broken M6 tap inside the M8 bolt.
The clients problems had been compounded by the fact that the heat of welding has resulted in the aluminium of the head melting slightly resulting in an already unmovable bolt being completely locked in. That said, in this case it didn’t make any difference in as much as the bolt was so seized it was never going to be unscrewed. it was either going to break as it did, or tear the thread out of the head.
Part way through the repair you can see that it has been necessary to chase the molten steel from the welding off to one side, and the flutes of the tap are now visible.
This is the tap that was broken off in the bolt. Once the tap and the broken bolt were removed a new bolt was tested in the thread. The thread was found to be so ‘stretched’ in the head the bolt was a very loose fit even though the threads were not damaged. The stretch damage to the threads was a direct result of the corrosion between the bolt and the head which is why the client was never going to be able remove the bolt.
As such a thread insert had to be fitted.