Some notes on the 1GM10 engine
I have put this on as a working set of notes I have been compiling - rather than all on scraps of paper ! I'm looking onto rebuilding the engine next year - so sorting out sources and possibilities !
I say again about the online Ribparts site, It really is the most useful parts site for Yanmar engines. The entire elecronic parts catalogue for all engines - use it with IE and download 'Isoview' and you can see all the exploded drawings as well. ( all java of course but you do know about the 'print screen' button ? if not | see here )
Its just as I compliled it - so nothing special, but its up to date for resources ( I'm doing this now Jan 2014 )
General - only special tool for stripping crankshft and canshaft - 36 long reach crank socket ( main nut holding on the governer weights and crank gear )
Crankcase solid bearings need pressing out - but only front end is captive in block - rear flywheel end has removable bearing housing.( ie Crank just lift out once housing is removed )
The camshaft has front ballbearing race held in place by a small screw - and the rear appers to just sit in a housing in the block ? No mention in the workshop manual about any removable bearing face there - seems odd ?
I would have thought the front crankcase solid bearing face could stay in situ for any rebore work ?
No flywheel puller needed - five bolt flat face mount.
General puller for fanbelt pulley - ( ie toolstation - or below )
They do recommend a ridge reamer for removing the piston upwards - but if new rings at least are being fitted - then I think the piston would come out - without prior reaming ? (maybe check this )
Cylinder would be honed at least anyway with new rings.
Need Micrometer set - see Chronos below and bore gauge. Maybe these could be hired ?
Cheap enough - nice to have
Crankcase nut - spec at
36mm - max 49mm - open long reach 140mm
http://www.williamstools.co.uk/melco-tim9-iso-metric-box-spanner-36mm-x-41mm-x-175mm-7--tim9-30519-p.asp @ £ 26.00
Thomas Meldrum Limited
Tel: 0114 2725156
TIM.9 - 36 x 41 - 7 - 175 - @£16.88 - plus vat
Cheapest from sound source - Chronos Ltd
( yanmar recommend 4 - 0 - 100mm )
French Marine really know what they are talking about.01206 302133
Rollo - can get anny part within a week.
Keyparts cheap( but often aftermarket on gaskets etc ! ) free postage.
RibsParts - access to online EPS dealer style database, Using IE and download of Isoview - you can see all the exploded Yanmar parts drawings - superceeded parts etc - for all models. Extremely useful - shame it only works with IE for online sales and drawings.
Also Marine Power - and others.
Oversized piston and rings are available - as specified in the manual, but do not show on the general dealer database ! Keyparts accessed the documentation they have to confirm this. Its listed on a supplementary sheet, which appears not to be digitised - ie its on paper !
Part no - 105325-22570 piston and rings +.25 - 1GM10
105225-22570 - rings +.25 only.
seems there is also .50 rings listed but manual says not to bore over .25 ?
Valve guides - inlet and exhaust 128170-11160
valve spring retainer caps - 104200-11180
cotters - 27310-070001
Valve exhaust - 105225-11110
Timing shim set(under the inejctor pump) about £10 - 104271-01950
Pre Combustion chamber lower packing x 2 124950-11450
Rocker gasket - 128170-11310
Valve stem seals - 12870-11340
Water pump bearings - Koyo 6000 CM 01215 ( stocked at Simply Bearings - about £2 )
Small seal - NOK AE01451 dims 8 - 18 - 7 inner, outer, depth
Large seal - SD 8 - 22 - 7 ( simply bearings have sizes - but not the same make ) - cheap, They are available from Yanmar - dear !
Circlips - large, 26 - thick 1.7mm - small ( between the bearings ) 10mm 0.94
Alternator bolt(M8x120 ) 26106-081202
Oil Pump rotor assb - 728170-32500 - £76.00
Part - Cost Approx retail, bottom end
Crank main bearing - oil seal 21.00 - main metal ( housing bearing) 20.00
Camshaft ball race - £12
oil pump rotor - £76( but not recommended - rotor only ! - new oil pump pricey - 200 plus - check that one )
Gasket set - French marine, £95 inc vat( check whether this is Yanmar )
Oversized piston and ring - £150
note - circlips are available as parts for water pump - £1 or so
Specs ( mm )
Bore specs - measure NS/ EW and at 10.5 - 105.5 down and middle.
Diam standard - 75.00 - 75.03 - wear limit - 75.10
Out of round - standard - 0.01 - wear limit 0.02
Note - bore diam should not exceed 75.10 - but not sure on differences between top and bottom - when out of round is in spec ? ie 75.05 bottom - 75.10 top ? ( need to check this out )
Block - 'out of flat' - limit 0.05 ( head - 0.07)
Piston - with gasket off, should be above block approx 0.6mm tdc( rough figure) - Old gasket clocked at 1.35 thick.
Top clearance - Spec - 0.68 - 0.88.
Valve seat width - spec 1.77 - no wear limit specified. Note that too wide is not good.
( Note - my engine - 1st strip down on head, seats clock at 1.85 before any lapping. With a good lap in on the exhaust - barely much wider - maybe 2mm )
Yanmar say if the seat is reground( as opposed to lapped ) - a shim should be placed under the valve spring. Presumeably to correct spring tension ?
Valve head recess/ Spec - 0.95 - limit 1.25 ( valve head below head surface)
Valve tilt value - max 0.036
ie valve on flat plate against a square. Max gap against square, top or bottom at any position = B. Height of free length of spring = A . Tilt value = B/A -
Note - 1.4mm 'lean' off square = 0.036 approx. So old rule of 'about a 1/16th' out of square as max lean look good info.
Mine are 1.4 mm off - so I may fit new springs ?
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