| Tricks of the trade | | | | oversized ring spanner, but with a blade which can be |
| The possibility that you might take an engine to | | | | screwed in to break a seized nut) to split the nut, or |
| pieces and not be able to put it back together is | | | | a hacksaw to cut the side off it. Bolt heads that |
| probably the home mechanic's worst nightmare. The | | | | have rounded off can be carefully filed down to take |
| best tip for avoiding it is to be scrupulously and | | | | the next size of spanner, or can have a slot |
| relentlessly methodical, lay the bits of your engine | | | | hacksawed in. Most drastic of all, but often quickest, |
| down in the order they were removed, and keep the | | | | is to cut through the bolt completely. |
| fasteners with the relevant part - don't tip all the | | | | Destroying a nut and bolt isn't too frightening |
| nuts and bolts into one box- because it may then | | | | because it can always be replaced, but the idea of |
| take hours of trial and error to find the right one. | | | | cutting or snapping a stud or bolt that has seized into |
| Don't complicate matters by taking things apart that | | | | a casting is more worrying. Even so, it's not the end |
| you don't have to. It almost goes without saying that | | | | of the world. |
| you should refer to the manual for any job that is | | | | Once the load has been removed from the broken |
| not completely familiar to you, but if you do find | | | | stud, it may unscrew relatively easily, particularly if it |
| yourself working without a manual, don't be afraid to | | | | has been well soaked with penetrating oil. This is |
| make notes or sketches of the order in which things | | | | where mole-grips come in handy. Alternatively, you |
| came apart or what went where. Look carefully at | | | | could try cutting a screwdriver slot in the remains, or |
| any component before you remove it, and try to | | | | screwing two nuts down on to it. Once the second |
| figure out what it does, which bolts hold it on, and | | | | nut has been tightened down hard against the first, a |
| which hold something inside it. Marine engine centre | | | | spanner applied to the lower nut can be used to |
| professionals do many of theses things instinctively, | | | | unscrew the stud. |
| even though they have fancy aids to diagnosis like | | | | If the stud has broken off flush with the casting, it |
| electronic engine diagnosis. | | | | should be possible to drill a hole down the centre of it |
| Seized fasteners make life difficult, but are a | | | | in order to use a tool called a stud extractor. This is a |
| common feature of many boat engines. Before | | | | tapered rod of hardened steel with a very coarse |
| applying brute force, it's important to bear in mind | | | | thread cut into it. The stud extractor's thread is in |
| that conventional spanners are designed to apply the | | | | the opposite direction to that of a conventional bolt, |
| right amount of leverage for the fasteners they fit, | | | | so as you screw the stud extractor into the stud, it |
| and that if you lengthen a spanner to unscrew a bolt | | | | first grips the side of the drilled hole, and then |
| that is already weakened by corrosion, you may | | | | unscrews the stud. |
| make it shear off completely. | | | | If this doesn't work, it may be possible to drill out |
| The first stage is to make sure that you are working | | | | the stud altogether, and then use a device called a |
| efficiently: | | | | tap to recut the thread in the hole. Taps, |
| Try to give yourself as much room and light as | | | | unfortunately, are quite expensive, so it's hardly |
| you need by removing any covers or hatches that | | | | worth having a full set in hand to cope with the |
| are in the way. | | | | occasional mishap, and it may be worth referring the |
| Keep your hands and tools clean so that you can | | | | job to a professional. |
| get a good grip. | | | | Full engine reconditioning service |
| Pull on the end of a spanner: you are less likely | | | | The ultimate sanction is definitely a professional's job |
| to get hurt if the spanner slips when you are pulling | | | | because of the equipment required, but it's worth |
| than pushing, and the end gives you more leverage. | | | | knowing that it is possible to drill out the hole |
| Use a ring spanner if possible, rather than an | | | | oversize, and put in a completely new thread. These |
| open-ended one. | | | | devices are known as helicoil inserts. |
| Turn the nut rather than the bolt. | | | | It is arguable that if an engine is in this state in the |
| If that doesn't do the trick, it's worth trying to | | | | first place, it is worth putting in the hands of a marine |
| tighten the offending fastening to break the bond | | | | engine centre. He will use electronic engine diagnosis |
| between the threads, and penetrating oil can work | | | | in the first place. He might well be able to build and |
| wonders so long as it is left alone for long enough to | | | | supply complete diesel inboard engines to spec which |
| penetrate. | | | | gives him the knowledge and experience. |
| More drastic measures include lengthening the | | | | He might be an approved service centre offering full |
| spanner with a length of pipe; and shock treatment | | | | engine reconditioning service of your particular brand, |
| by tapping the spanner with a hammer while applying | | | | Steyr marine diesel engine. He will almost certainly be |
| steady pressure by hand. | | | | able to get parts cheaper from a single source |
| For a really stubborn fastening, you may have to | | | | supplier like Sierra Marine Parts, plus he will get you a |
| resort to more destructive methods such as using a | | | | deal on accessories because he might be Piranha |
| cold chisel or a gadget called a nut splitter (like an | | | | propeller agents. |