My en­gine won’t give up smok­ing

Canal Boat - - Back Cabin: -

QMy diesel en­gine’s in­jec­tors have been cleaned but noth­ing has been done to the in­jec­tor pump apart from re­tim­ing it. The en­gine is emit­ting blue smoke when idling (even when warm), but un­der load there’s no smoke. PETER DEKKER, via email

ATONY REPLIES: Blue smoke is nor­mally pro­duced by burn­ing oil. My ini­tial re­sponse is that I would ex­pect this from a newly over­hauled en­gine, caused by burn­ing of the oil used dur­ing the as­sem­bly of the pis­tons and valve gear, or by the pis­ton rings hav­ing not yet bed­ded into the cylin­ders and pass­ing oil into the com­bus­tion cham­ber. Run in the en­gine un­der vary­ing loads, not much on idle and light loads and avoid max­i­mum speed for sev­eral hun­dred hours.

Clean­ing the in­jec­tors might only con­sist of a quick wire brush over the noz­zles with the po­ten­tial to snap a nee­dle pin­tle, which may well cause smoke. In­jec­tors need strip­ping, in­spect­ing, clean­ing and test­ing as part of an over­haul.

There are four tests, spray pat­tern, break pres­sure, drib­ble, and back leak­age. Do you have the re­sults of these tests?

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