7/26/2019 BW4.Injectors http://slidepdf.com/reader/full/bw4injectors 1/5 ENGINES ENGINES FUEL INJECTORS G iven a supply of clean fuel, injectors usually work without complaint for many years. But if at some point the performance of your engine begins to decline—particularly if it has difficulty starting, smokyexhaust, high fuel consumption, or runs rough, especially while idling—the injectors may be the cause. Though they have a long working life, they do eventually wear and need servicing. When problems arise, they can be dealt with quickly and cheaply by removing the injectors and taking them to a diesel-injection specialist. Removing injectors is a do-it-yourself job, but servicing them is definitely not. The precise manufacturing specifications require specialized equipment and a clean working environment. You don’t need a marine specialist. Check your local Yellow Pages for a service provider for diesel trucks. Unless an engine’s poor performance is clearly caused by some other factor, always consider servicing the injectors first. Injectors are the cheapest items to deal with and may solve the problem without further expense. Even if the problem is eventually found elsewhere, the overhaul is worth the few dollars it will cost you. Most engine manufacturers offer specialized tools for removing injectors, but you won’t need one unless your engine is made by Volvo-Penta. Many Volvo engines use a sleeve, rather than the more common copper washer,to seal the injectors. With sleeved injectors, using a special tool that removes the injector while holding the sleeve in place is almost compulsory. If the sleeve has been disturbed, a new one must be installed—a costly job that requires a specialist. Removing sleeved injectors without a special tool is possible, but there is always the risk of disturbing the s leeve. n Keeping your engine running at peak performance requires routine maintenance. Top: Injectors are simple to replace;this one’s from Yanmar Injectors will often last for years without giving any signs of trouble.If your diesel is hard to start,has a smoky exhaust,or runs rough when idling,it may be due for an injector overhaul. Story and photos by Peter Caplen Fuel injection inspection B OA T W ORKS SUMMER 2005 | 33 M a r k C o r k e
Transcript
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ENGINESENGINES FUEL INJECTORS
Given a supply of clean fuel,injectors usually workwithout complaint for manyyears. But if at some point
the performance of your engine beginsto decline—particularly if it has difficulty
starting, smoky exhaust, high fuelconsumption, or runs rough, especiallywhile idling—the injectors may be thecause. Though they have a long workinglife, they do eventually wear and needservicing. When problems arise, theycan be dealt with quickly and cheaply byremoving the injectors and taking themto a diesel-injection specialist.
Removing injectors is a do-it-yourself job, but servicing them is definitely not. The precise manufacturingspecifications require specialized
equipment and a clean workingenvironment. You don’t need a marine
specialist. Check your local YellowPages for a service provider for dieseltrucks.
Unless an engine’s poor performanceis clearly caused by some other factor,always consider servicing the injectorsfirst. Injectors are the cheapest itemsto deal with and may solve the problemwithout further expense. Even if theproblem is eventually found elsewhere,the overhaul is worth the few dollars itwill cost you.
Most engine manufacturers offer
specialized tools for removing injectors,but you won’t need one unless your
engine is made by Volvo-Penta. ManyVolvo engines use a sleeve, rather thanthe more common copper washer, toseal the injectors. With sleevedinjectors, using a special tool thatremoves the injector while holding thesleeve in place is almost compulsory. If the sleeve has been disturbed, a newone must be installed—a costly job thatrequires a specialist. Removing sleevedinjectors without a special tool ispossible, but there is always the risk of disturbing the sleeve. n
Keeping your engine running at peak performance requires routine m aintenance.Top: Injectors are simple to rep lace; this one’s from Yanm ar
Injectors w ill oftenlast for yearsw ithout giving any
signs of t rouble. Ifyour diesel is hardto start, has asmoky exhaust, orruns rough w henidling, it m ay be duefor an injectoroverhaul.Story and photos byPeter Caplen
Fuel inject ioninspection
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ENGINESENGINES
1On this Volvo engine, firstremove the high-pressureinjector pipes that run fromthe injection pump to ea chinjector. These arepreformed steel and m ustnot be d istor ted. I t i spossible to bend t hem out ofthe way, but on smal lengines with short piperuns, this is bad pra ctice andcan ultimat ely lead to pipefai lure. Loosen the pipefi tt ing on top of eachinjector and unscrew until
free.
2 Do the same at the otherend of each pipe, and thenunbolt any supportingbrackets along the length ofthe pipes. Once free, l i ft thepipes clear of the engine.
3 Next disconnect t he fuelreturn pipes running fromthe side of each injector tothe top of the fuel f i l ter.Each connection consists ofone bolt and two smallsealing washers. Note t heposition of these washers oneach side of the banjo joint(so-called for it s vaguesimilari ty to the instrument)for subsequent refitting.
4 The injectors are normallyfixed into position w ith onebolt that holds a securingbracket over the injector.Once the bolt and brackethave been removed, theinjector-extraction to ol is
screwe d onto the top of theinjector. Tighten t he nut o ntop of the tool; this draw sthe injector gently upward.
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5Once the injector is free,carefully li ft i t out. (Notethe securing bracket heldalongside the injector.)
6 With the injector removed,check for signs of blow -by— gases leaking from thecompression chamber—indicated by soot up t heside of the injecto r,corrosion, or other damage.To rep lace the injector,reverse the removalprocedure. Tighten t he
securing-bracket bolt firmlyto the t orque settingrecommended by themanufacturer, but not toomuch. Once the engine isrunning again, check forblow-by. I f you find aproblem, t ighten thesecuring bolt some more.
7 Lucas/CAV-type injectorsare fi tted to most othermak es of diesel engines.Regardless of the make ofinjector (Bosch, Stanadyne,and Denso are somebrands), the procedures forremoving and replacingthem are t he same.
As with the Volvo injectors,you must disconnect theassociated fuel pipe sbefore the injectors can beremoved. The return pipesjoin all the injectors to thereturn connection on t op ofthe fuel f i l ter and then leadback to the top of t he fuel
tank w here excess fuel andany small quantities of airare deposited. Theconnection to each injectoris the same banjo jointseen on the Volvo.
8 During disassembly, carefullyretain the soft aluminum orcopper w ashers used to forma seal betw een the
retaining bolt and the banjojoint (tw o per connection).
9The preformed steel
injector t ubing must bedistorted as l i tt le aspossible while youdisconnect it from theinjector. On larger engineswith much longer pipe runs,the pipes can be gentlyeased away from theinjectors as the nuts areunscrew ed rather t hancompletely removed.
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10These injectors may be held in thecyl inder head w ith tw o studs andnuts. Remove the nuts byslackening them equally a little ata time, to avoid distorting theinjector. I t is good practice t ocover the end of the injector pipeonce it’s disconnected so no dirtcan ente r.
11 An injector that has not beendisturbed for several years willprobably be diff icult to removefrom i ts bore, as carbon depositsw il l have bui lt up a round the tip.
Apply a generous portion ofpenetrating oi l around theinjector body and into the boreto break up any corrosion seal.Let i t soak in for a few minutes(or a fe w hours, i f i t ’s real lystubborn) before atte mpting toremove the injector.
12 A l ight tap w ith a soft-facedhammer— or l ight hammeringagainst a block of wood— aroundthe body is usually sufficient tofree the injector. I f i t isparticularly obstinate, you mayneed to lever i t up w ith a barunder the securing flange whileyou gently tap around t he body.Ensure that the leverage does notdistort the securing studs, and donot e xert e xcessive force in anyone place. Patience and l ighttapping w i l l eventual ly do thetrick.
13 Once the injector begins to move,i t can be l i fted out of i ts bore.
14With the injector removed, check
that the copper seal ing w asher isstil l attached to the e nd of theinjector body. I f i t isn’t, you’ ll f indit at the bott om of the injectorbore. Hook i t out wi th the end ofa screwdriver or similar tool . Beparticularly careful not to dropthe tool inside t he cyl inder; you’ llhave to rem ove the cyl inder headto retrieve i t .
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15Wipe out t he injector borew ith a clean rag wrappedaround a suitable rod; thehandle of a socket w renchis ideal.
16 After servicing, refi t theinjectors. First replace theseal ing washer. New onesare generally suppliedw hen the injectors areoverhauled. I f for anyreason new w ashers are notavai lable, the old ones canbe annealed to renew t heir
seal ing properties. Heatthem cherry red over astove burner or a blowlamp and then plunge theminto cold wate r. Fit the neww asher over the end of theinjector body prior toreplacing the injector intoits bore in the head.
17 Run the retaining nutsdow n the studs unti l theyare finger-tight, and tightenboth equal ly w ith a socketor other w rench to e nsure agas-tight seal . Being carefulnot to distort the pipew ork,refi t the injector pipeconnections and firmlytighten the nuts. Also takecare not to strip the finethreads throughovertightening whenrefi tt ing the tubing. Just nipthem up enough to preventleaks by lightlycompressing the softsealing wa shers on eachside of the joint face.
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BANJO UNION S
The retaining bolt on each banjo jointis drilled through the middle and alsoin the side to coincide with a channelaround the inner edge of the banjoitself.This channel has one or tw ooutlets that al low connection to thereturn pipes.
IN JECTOR SERVICIN G
Once the injectors have been removed,w rap them up careful ly, taking care toprotect the small nipple on the end. I fthis is broken, a new end cap wi l l berequired, raising the price of theoverhaul .The injectors can be taken toany diesel-injection specialist f oroverhaul . Costs vary, but t ruck de alers are usual ly the least expensive.
STARTIN G THE ENGIN E
I f there is evidence of blow-by from an injector once the engine is started, the tw omost l ikely causes are that the seal ing wa sher has been inadvertently om itted o r thereta ining nuts have bee n tightene d unevenly.The cure for either problem is obvious.
THINGS TO REM EM BER
Bleeding the system should not be necessary if the injector pipes have not beenremoved. On small engines w here the pipes w ere removed, simply loosen the pipeconnections and turn t he engine a couple of t imes on the starter to fi l l the injectorpipes and clear the air.Aft er the pipe connections are retightened, the engine shouldstart normally. I f i t doesn’t, repeat the pipe-bleeding procedure.
