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                     RECONDITIONED ENGINES   

Over the coming months we will have fully reconditioned engines, in 'short' or 'core' or 'full' motor form, for popular models which will become available from stock.

As these become available, they will be listed here. However, please let us know if you have a particular requirement if not already listed. Your engine type may be next on our rebuild programme so one can be prepared for you.

Example of a core engine..

Kubota short motor 1.jpg

Short Motor Build Specification

Machining & Services:  All components chemical cleaned, paint removed and descaled back to bare metal.

Cylinder Block: Rebore & hone cylinder bores, resurface top deck, re-tap all threaded holes.

Crank shaft: Visual inspection, re-tap flywheel bolt holes, “NDT” crack test, measure journals, polish or regrind as necessary.

Conrods: Visual inspection, check & replace small end as required, measure big end bore – proof hone or resize as required. Check for bend and twist.

Gears & Cams: Visual inspect fuel cam, valve cam, gears & governor parts. Replace parts if required.  Cam followers re-faced.

New Parts: Pistons, rings, main bearings, conrod bearings, crank – thrust washers, core plugs.

Assembly: Fit up conrod and main bearings prior to assembly and check running clearances, measure piston to bore clearances, measure ring gaps. Fit core plugs to block, paint block, fit crankshaft assembly to block, fit piston & conrod assemblies to block, fit fuel & valve cams – gear train, measure and adjust piston heights as required.

Parts Not Included in a Short Motor
Cylinder head, fuel pump, timing cover, rear crank seal, flywheel or back plate, oil pick up pipe, sump.

Short Motor  

Core Engine

A core engine is a short motor with timing gears and camshafts. A fuel injection pump is fitted and spill timed. The cylinder head is fitted complete with valve gear (tappets set). A set of injectors are also fitted.

Fit the following parts from your old engine.

Front end: front timing cover and pulley, water pump and thermostat housing.

Back end: back plate or bell housing and flywheel.

Bottom: oil pick up pipe, sump.

Top: manifolds, rocker cover, pipes, stop solenoid and control plate.

Core engine 3.jpg

Overhaul details

Block:  Full hot tank clean back to the bare metal, inspection, check thread holes and casting, resurface top face, rebore and hone cylinder bores.

Crankshaft & bearing carriers: crack test “NDT”, measure and assess crank, lap or regrind crankshaft, grind true rear crank flywheel mounting flange.  Inspect and measure main bearing carriers.

Conrods: check for bend and twist, check or replace small end bushes as required, measure large end bore/resize if required.

Cylinder Head: Hot tank clean back to bare metal.  Inspect thread and casting, pressure test cooling jacket, check valve guide bores – reclaim or replace as required. Recut valve seats,  resurface main gasket face, reface or replace valves, test and guage valve springs – replace as required.  Fit new valve stem seals, fit up valves ad springs, vacuum test valves.

Fuel Equipment: overhaul fuel injection pump, rebuild injectors with new nozzles.

Valve Gear: dismantle rockershaft assembly – inspect and polish shaft, reface rocker tips, clean and rebuild rockershaft assembly.

Misc: reface cam followers, inspect valve and fuel cams, inspect timing gears.

The Build: final clean all parts inspect and layout for assembly.

Paint block and cylinder head.

Measure piston to bore clearance, conrod and main bearing clearance and piston ring gaps.  

Fit up crank to block, fit piston and con rod assembles to cylinder bores, measure and adjust piston heights if necessary.  

Fit and time all gears,

Fit valves to cylinder head, spring up and vacuum test.  Fit new core plugs, paint cylinder head, fit head to block assembly using latest metal layer gasket,
fit valve gear and set valve clearances.

Fit fuel injection pump and spill time, 

fit 4 injectors, fit dust caps.

Full Engine 

One of our reconditioned

engines on test.

The full engine build spec is the same as the Core Engine spec above with the addition of fitting Sump - Timing Cover - New Waterpump - Thermostat - Oil Switch - Oil Seals etc ......

Each full engine is fully dynamometer tested - run in , cylinder head retightened , full power and max torque adjusted and recorded .. 

v1505 full engine_edited.jpg

Reasons for dynamometer testing:

Here at Jem Engines we have two fully equipped engine test cells dedicated to testing Kubota engines.


Every time we remanufacture a Kubota diesel engine we subject it to a run-in period after which the cylinder head is retightened “hot” and the valve clearances  checked and reset if necessary.

On completion of adjustments the test is continued and the engine is rigorously tested measuring and recording the maximum power and torque output. Oil pressure, coolant temperature and cooling performance are monitored. Exhaust emissions are also an important part of testing.

Dynomometer Testing 


dipstick Layout.jpg
Dipstick Position

When ordering an engine it is important that we know the dipstick position. 

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