Lis­ter SR4 or SL4 diesel

Canal Boat - - BACKCABIN -

QI have come to the end of my tether with this en­gine the prob­lem seems to be ex­ces­sive heat pro­duced when the en­gine has been run­ning for 30 min­utes or so we have even gone down the road of cut­ting a hole in the roof and putting a duct down from the roof with a large ra­di­a­tor type fan draw­ing in cool air right above the en­gines own fan and run­ning with the deck boards off. Af­ter a 30 minute run it will not tick over and if it restarts,when you try to rev it up it just doesn’t re­act but when cold its fine. the en­gine also has quite a bit of blueish smoke from the ex­haust. I must ex­plain that the en­gine came with the boat and was very tight through wa­ter ingress into one cylin­der we have re­moved the slight ring of rust in the bore and the en­gine has good com­pres­sion and starts very eas­ily and is now quite free with no signs of the seizure we also did the bump test and set it for the rec­om­mended 35thou it has prob­a­bly run now for about 20 hours and when just tick­ing over charg­ing bat­ter­ies will run all day its only when un­der cruis­ing con­di­tions that it has this prob­lem its as if it runs out of fuel but there is plenty of fuel get­ting to the in­jec­tor pump. I am quite knowl­edge­able with en­gines but this one has me beat. I hope you can give me some point­ers be­fore I go down the road of chang­ing the en­gine for some­thing more mod­ern.

Mike Dar­nell Note: to read­ers – I no longer run such cour­ses

ATONY REPLIES: When an air cooled Lis­ter dis­plays those symp­toms my first thoughts would be oil di­lu­tion caused by a bro­ken in­ter­nal fuel pipe or a loose in­ter­nal union. How­ever that nor­mally has two more symp­toms: a ris­ing sump oil level with the oil thin­ning. In the lat­ter stages when it causes stalling when hot there is usu­ally a smell of diesel around the en­gine. I note you do not men­tion those last set of symp­toms so if the oil level is con­stant it can not be that.

If there are no shaped pieces of “tin” with lit­tle loops on to slide over the cylin­der re­tain­ing head studs and pushed down be­tween the cylin­ders I ex­pect there is a good chance that fit­ting them will cure the prob­lem. If they are miss­ing I sus­pect the cylin­der fur­thest from the fan may be over­heat­ing and seiz­ing up. These air flow di­rect­ing plates are vi­tal on multi-cylin­der air cooled en­gines. It is also com­mon for the ducts to be fit­ted up­side down and that again starves cylin­ders of cool­ing air. This would be my first check. It is also vi­tal that the hot cool­ing air ex­pelled from the side of the en­gine (as­sum­ing the outer thin metal cowl­ing is not bro­ken and is in place) isn’t al­lowed to sim­ply cir­cu­late back into the en­gine room. When a duct broke on our SL4s on the hire fleet we of­ten found the in­serts in the pis­ton crown popped out de­mand­ing a new pis­ton and some­times a new con-rod and valves.

If this does not solve the is­sue talk to Ma­rine En­gine Ser­vices (Mid­lands)/ Prim­rose Engi­neer­ing who seem to be the in­land Lis­ter spe­cial­ist.

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