Diesel engine maintenance guide

Technical notes of interest to Marine Engineers

Maintenance guide for high speed Diesel prime movers

Compiled by: Martin Leduc

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These recommendation were specifically designed for a Cat D379. Which is a diesel fuel burning, V8, turbocharged, engine running at 1200 rpm, producing about 600 bhp. Engineers can use these maintenance guidelines for similar sized engines should they not be in possession of the OEM's maintenance recommendations.

Maintain a record of "fuel used", "service hours" or "time interval". Use one of these to provide a consistent benchmark for maintenance so as to prevent "lack of maintenance" and "over maintenance".


Check level

Engine oil
Engine coolant
Marine gear oil
Air starter lubricator oil (if equipped)
Governor oil (if equipped)
Air tank - drain water
Inspect for leaks and loose connections
Inspect engine air cleaner indicator - check
Oil filter differential pressure - check

Clutch shift collar - lubricate

Every 5300 L (1400 gal) of Fuel 
50 Hours

Zinc Rods - Inspect/Replace
Marine gear oil and filter - clean strainer / change on new or rebuilt marine gears at first 50 hours only, then at normal interval thereafter.

Every 13 260 L (3600 gal) of Fuel
125 Hours

Clutch - check / adjust
Lubricate clutch control Lever, clutch main shaft bearing and clutch pilot bearing.

Every 26 500 L (7000 gal) of Fuel
250 Hours

Batteries - clean / inspect and check electrolyte level
Belts, hoses and radiator fins (if equipped) - inspect / check
Fuel pressure gauge - check
Coolant additive - check and add as needed
Fuel tank and fuel filter housing - drain water and sediment

Every 79 500 L (21,OOO gal) of Fuel
750 Hours

Engine oil and filters - replace
Duplex oil filters - replace
Valve lash and rotators check / adjust (at first oil change only)
Crankcase breather - clean
Primary fuel filter - clean

Every 106 000 L (28,000 gal) of Fuel
1000 Hours

Engine protective devices - inspect / check
Marine gear oil and filter - replace
Governor oil (if equipped) - replace
Marine gear strainer and breather - clean
Marine gear output shaft seal, governor air
Actuator, tachometer drive and shutoff control lever - lubricate

Every 212 000 L (56,000 gal) of Fuel
2000 Hours

Valve lash - check / adjust
Engine mounts, damper, valve rotators
Turbochargers - inspect
Fuel filters - replace

Every 318 000 L (84,000 gal) of Fuel
3000 Hours - Two Years

Cooling system - clean / flush
Thermostats - replace

Every 424 000 L (112,000 gal) of Fuel
4000 Hours

Air compressor and electric starter - inspect / rebuild or exchange if necessary
Nozzles - test

Every 636 000 L (168,000 gal) of Fuel
6000 Hours

Alternator, water pump, sea water pump (centrifugal), air starter and turbochargers inspect / rebuild or exchange if necessary

Every 1,060,000 L (260,000 gal) of fuel
10,000 Hours

Top end - cylinder heads and after cooler core inspect / rebuild or exchange if necessary

Every 2,120,000 L (560,000 gal) of Fuel
20,000 Hours

Overhaul, inspect / rebuild or exchange if necessary

cylinder heads
connecting rods
cylinder liners
cam followers
fuel transfer pump
pre-lube pump
fuel injection system and governor
wrist pins
main oil pump 

Install new

piston rings
main bearings
rod bearings
valve rotators
crankshaft seats 


cam Bearings
gear train
rocker arm bushing
bushings and driven unit alignment

Clean / test

oil cooler
after cooler core
fuel nozzles 

As you can well imagine, it's easy for an engine company to increase your maintenance task so your engine doesn't fail on you making you curse them. But once you have established a set routine, the recommended intervals may be adjusted to be more in line with the actual need. This is called "condition based maintenance". 


Valve readings / adjustments on a six cylinder, four stroke engine, like a Cat 3406

Taking valve reading / adjusting can be a labour intensive task: take readings turn the engine, take readings turn the engine, on and on until all six cylinder are done. Well, start printing this page because were going to shorten the task. 

Harmed with a "go no go" feeler gauge and the manufacturer's recommended specs for the intake and exhaust valves... 

Set the engine to #1 top dead center (TDC) - valves on #6 are rocking and #1's are loose.

Measure and adjust 

intake valves on cylinder #1, 2, 4
exhaust valves on # 1, 3, 5.

Bar the engine over to  #6 TDC, 360 degrees - valves on #1 are rocking and #6's are loose. 

Measure and adjust 

intake valves on cylinder #3, 5, 6
exhaust valves on # 2, 4, 6

...for a Caterpillar 397
Bore 6.25 (158.8mm), Stroke 8.00 (203.2mm)

TDC #1

Exhaust to check 4, 8, 1, 5
Intake to Check 2, 6, 1, 3

360 TDC #1

Exhaust to check 2, 6, 3, 7
Intake to Check 4, 8, 5, 7

...that's it. Quick and painless. 


Genset maintenance

I've created this quick checklist to help me when carrying out maintenance on our ship's gensets. Most gensets on the smaller vessels I've worked on were 150 kW units typically powered by a Cat 3306, Detroit Diesel 8V92 or the likes (high speed diesel, four or two stroke, turbo charged). The maintenance interval for oil changes ranged between 300 - 400 hours and included the following:

Take SOS (Schedule Oil Sampling) sample prior to shutting down. SOS is optional and "expensive", but properly used, it can provide a clear picture of the engines condition and provide information to alter your maintenance practices. 
Change oil and filter
Drain fuel / water separator (Racor) of water and dirt. Change filter every other service (600hrs - Racor recommends every 500hrs but we've run them up to 1300hrs)
Check governor mounts, clevis pins and connections. A runaway engine can ruin your day - been there, done that. 
Check air intake filter. Replace if you can't see daylight through the edge of the pleats. 
Check turbo end play for axial and radial play. Gently push / pull and try to move the end of the turbo shaft sideways - tight is good, but some play is allowed - check your manual for specs. Also check condition of compressor blades - foreign object damage and cracks.
Check fresh water header tank for level and proper conditioning. You don't specifically need antifreeze (glycol) but your diesel does need a conditioning agent. Cat Alcool or Drew Chemical's Maxi Guard are both solution which provide conditioning. If you do have glycol in your engine, keep it at 50% water, 50% anti freeze and you will need additional conditioning.
Check / replace zincs on raw water system. Check all the plugs around the sea water piping and heat exchanger they might need new zincs to prevent galvanic destruction.
Check engine mounts. Detroits are particularly bad for this. Lightly tap each engine / generator mount bolts with a small ball peen hammer - "ping" = good (tight), "thud" = bad (loose). While you're at it, do a visual on the all the engine's piping and connections.
Check alternator end for loose connections, chaffing and dust build up. Take some of the housing covers off and do visual inspection, blow out dust with compressed air. Some generators have air filters, check and replace as necessary.
Log your efforts. Not for praise, but for record keeping - so you won't do it too often or not enough ! 

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