Kohler KD350 - Hydraulic Tappets KD 400-440

8
- 24 -
DISASSEMBLY/REASSEMBLY
Caption
1-Lockring
2-Uppercollar
3-Oilinletholes
4-Low-pressurechamber
5-Piston
6-Play-recoveryspring
7-Case
8-Areatobelubricated
9-High-pressurechamber
10-Checkvalve
11-Identicationmarks
Fillthelow-pressurechamberthroughtheoilinletholes.
If clearance occurs while running, as the tappet returns to the base of the camshaft, theplay-recovery spring stretches out,
keepingalltimingsystempartsclosetogether.
While the play-recovery spring is stretching, the check valve lets oil into the high-pressure chamber from the low-pressure
chamber,torecovertheincreaseinvolumeinthehigh-pressurechamber,causedbythestretchingspring.Inthisway,sinceoil
ispracticallyuncontrollable,whenthevalveisnextopened,playwillbecompletelyrecovered.
Duringeachcycleasmallamountofoilisdrawnfromthehigh-pressurechamberintothepistoncouplingwallwiththecaseand
then,passingthroughtheinternalinlethole,owsintothelow-pressurechamber.
Thetappetisshortenedbylessthan0.1mmeachcycle.Thisallowsthetappettomakeupthereductioninplaywhiletheengine
isrunning.
Itisnotnecessaryfortheoiltoreachthetappetonthedownwardstroke:lightpressureisenoughtoensurethatairbubblesdo
notform.
Thetappetmaybesuppliedwiththehigh-pressurechamberfullorempty.Thelow-pressurechamberisalwaysempty.
Thetappetshouldalwaysbehandledinanuprightpositiontopreventthehigh-pressurechamberfromemptying.
Thesurfacethat comesintocontact with thecam should belubricatedgenerously duringassemblyusingAS COMPUND 40
typeMOLYSLIP(seegure).Thisoperationisimportanttoensurecorrectlubricationrightfromthestart.
Thedistributionsystemisassembledasfollows:
a)MakesurethatthepistonisbetweentheBottomDeadCentreandthehalfwaypoint
b)Inserttherodsintopositiononthetappets
c)Mounttherockerarmandthejointblock,thentightenthexingnuttothespeciedtorque
d)DONOTSTARTTHEENGINEFORATLEAST4HOURSAFTERTIGHTENINGTHEROCKERARMSbecausethevalve-
pistoncontactmaybeputatrisk.
Thetappetisunloadedwhenitispossibletoshifttheinternalpartby3.5÷4mmusingaforceof30Nm.
Ifthetappetsareloaded(forexampleiftheyhavebeenleftinahorizontalposition)theenginewillbenoisyduringtherstfew
minutesafterswitchingon,untiltheairhasbeencompletelydrainedoutoftheinsideofthetappetsthemselves.
KD 225_315_350_400_440 Workshop Manual_cod. ED0053029330_1° ed_ rev.00
Hydraulic tappets KD 400-440
Distributionuseshydraulictappetsforautomaticadjustmentofvalveclearance.
ThegureshowsthetappetusedinKD400engines.