Answer MEP Question 8

Q. Describe the procedure to remove a seized fuel injector body from the cylinder head when it could not be removed by conventional means. Also, list out preventive measures which could be implemented in the vessel so that such a seizure can be prevented in the future. 

Carbon soot and high temperature between the injector body and pocket causes it to seize. Sometime it becomes very difficult to remove the injector out of the pocket, Non conventional methods can be used to remove injector when such a condition exist, Precautions must be taken because these method involve high force, injector can jump out and injury to personnel can take place. The Nuts must not be removed out completely till the injector is loose. 

 A. Use of special Tool

A special tool is provided by the manufacturer to draw a sticky injector out of pocket shown in the figure.

Remove the nuts but not completely out and fix the tool as shown in diagram. The tool is constructed in such a way that a long lever provided in the tool transmits a high torque which pushes the injector out of body. Sometime a little tapping by hammer assist in the job. 

In case the injector is still stuck, a rag soaked with release oil to be rapped around the injector. The oil will seep into the clearance and dissolve the hard cake, it should be left there for some time. Now the process of extracting with special tool can be repeated, with a little hammer tapping. As the injector is loose, now the nuts can be removed compeletely and so the injector. 

B. Cooling the injector: 

Metals property of expanding with increasing temperature and contracting by cooling is useful when clearance between the mating surfaces is negligible.

Using a release oil and forcing the injector out if failed, the injector can be cooled by using ice. Use a cylindrical dam or a small piece of pipe to keep ice around the injector. Let the injector get cooled for sufficient time. Now the process of extracting the injector by using special tool should be applied.

C. Pulling by using chain block:This is a dangerous process require high level of safety to be followed. Slig wire and chain block is used and arranged as shown in diagram. The may also require assistance of the tool. Take care that the pulling should  be in the direction in the axis of injector, Nuts should not be taken out completely before injector is loose.