COOLING SYSTEM - M.6 Fig. M.8. Removing Sea Water Pump from back of Timing Case. It may be advisable to apply a soapy solution to the pump shaft in order to ease the seal past the circlip groove. Should  difficulty  be  experienced  in  gripping  the seal with the fingers then two lengths of stiff wire or   welding   rod   (3/64   in   to   1/16   in   dia.)   with hooked  ends  (1/16  in  to  3/32  in  deep)  can  be utilized   to   secure   the   seal,   one   opposite   the other, whereupon the seal can then be withdrawn. Alternatively,   slacken   off   the   clamping   device which   secures   the   two   halves   of   the   pump together  (bearing  housing  and  impeller  housing) and    then    proceed    to    separate    them,    thus exerting pressure on the seal from behind. 7. Remove the gear from the drive end of the pump shaft by means of a suitable puller. 8. Remove   the    outer    retaining    circlip    from    the bearing housing. 9. Withdraw  the  impeller  housing  from  the  bearing housing,    firstly    slackening    off    the    clamping device. 10. Withdraw the slinger from the pump shaft. 11. A  suitable  press  may  then  be  used  to  press  out the   water   pump   shaft   together   with   the   water pump bearings. 12. Remove the bearings from the water pump shaft by means of a press.  To re-assemble the water pump, the reverse order should be adopted. When    replacing    the    cam    fitted    in    the    impeller housing,  be  certain  to  coat  the  entire  top  surface,  rear face  and  securing  setscrew  hole  with  a  suitable  jointing compound. Note that the cam will go into position one way only. Care   should   be   taken,   when   replacing   the   rubber impeller,   that   all   the   blades   lie   in   the   same   direction relative to rotation of the pump i.e., blades trailing. When re-assembling, ensure that the rubber impeller is coated with MARFAK 2HD grease. NOTE: If appreciable wear or scoring has taken place on the wear plate working face, it may be turned round so  that  the  reverse  side  now  becomes  the  working face.      If   this   face   in   turn   becomes   worn,   then  a replacement wear plate should be fitted. If appreciable wear or scoring has taken place on the   end   cover   working   face,   it   can   be   ground   to restore  flatness,  providing  that  this  operation  is  not carried  out  too  many  times.    If  a  replacement  end cover is fitted which does not carry the pump model number   etc.,   then   the   original   worn   end   cover should  be  fitted  over  the  new  part,  utilizing  longer setscrews. The thickness of the end cover joint is critical.  If it    is    damaged,    it    is    important    that    the    correct replacement   joint,   or   one   of   similar   thickness   be fitted. HEAT EXCHANGER AND OIL COOLER (lowline engines) With   lowline   engines,   the   heat   exchanger   and   oil cooler   are   two   separate   items   both   mounted   on   the starboard side of the engine.  The oil cooler and spin-on lubricating oil filter are an integral unit. Removal  of  both  units  is  effected  by  removing  the inlet   and   outlet   water   connections   and   removing   the units from the cylinder block. The dismantling of both units is similar.  Remove the end   covers   and   drive   the   tube   stacks   out   of   their respective housings.  Cleaning of the tube stacks is the same   as   that   recommended   for   the   earlier   combined heat exchanger and oil cooler as given on Page M.7. When  re-assembling,  new  "O"  ring  seals  and  joints should   be   fitted   if   they   appear   to   be   badly   worn   or deformed. HEAT EXCHANGER AND OIL COOLER (earlier engines) The unit basically comprises: — (a) An aluminum casing providing the header