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MERCEDES-BENZ OM636 |
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We
offer a reliable and prompt delivery service
OM636 HISTORY Numerous other
automotive applications include the Unimog 411 and L319D as well as forklift
trucks (Still, Irion and Steinbock), farm tractors (Fahr D177, Güldner A4MS,
Bührer UM4 and Hürlimann), combine harvesters (Claas, Fahr, Köchel u. Böhm
and Dechenreiter) and the articulated mini-skidder Gafner (US). The OM636 was
also often used to power electrical generators (van Keyk) and stationary
water pumps. Readily marinised by
fitment of a heat exchanger and sea-water cooling system, the OM636 is a
popular fitment in many yachts and cruisers throughout the world. It has has
earned an outstanding reputation for economy and durability over the years
which contributes to its continuing popularity with boatowners in the 21st
century. During the 60s, 70s
and 80s, the OM636 was marinised by a number of specialist firms throughout In the After the end of
production in OM636 TECHNICAL DESCRIPTION The cast iron
crankcase has integral cylinders with a standard bore of 75mm. Reboring is
possible up to a maximum bore of 77mm. Pistons are available in 4 repair sizes.
It is also possible to reline the block back to standard bore. The injection pump and
oil filter are located on the right hand side of the engine (as seen from the
flywheel end). The generator, starter motor, oil dipstick and breather pipe
are on the left. At the front, an alloy timing cover encloses helical gears
driving the camshaft and injection pump off the crankshaft. A side cover
seals the valve lifter chamber. The alloy oil sump is bolted to the
crankcase. The cast iron cylinder
head is fastened to the crankcase by hexagon-head bolts. A composite cylinder
head gasket seals the combustion chambers and water passages between the head
and the crankcase. The cylinder head features removable precombustion
chambers into which injectors atomize the diesel fuel for combustion.
Preheater plugs are used as a starting aid. An alloy rocker cover with an oil
filler seals the top of the cylinder head. The 3-main bearing,
drop-forged crankshaft has hardened bearing surfaces. The centre bearing
serves as the thrust bearing. Counterweights on the crankshaft compensate for
the rotational inertia in relieving the forces on the main bearings. The
coolant pump is driven by a 'V' belt pulley fitted to the front of the
crankshaft. The forged steel connecting
rods are equipped with bronze bushes at the small end to accommodate the
piston pin and a 2- piece friction bearing at the big end. The bearing cap is
secured to the conrod by 2 special bolts and nuts. The alloy pistons
feature 3 compression rings and 2 oil scraper rings. The floating piston pin
is retained by circlips. The piston crown is dished. The drop-forged
camshaft with hardened bearing surfaces and cams is supported by 3 alloy
bearings in the crankcase. Axial movement is controlled by the front camshaft
bearing which together with the 2nd camshaft bearing is of a split design. Each cylinder features
an overhead exhaust and inlet valve opened and closed by the camshaft by
means of mechanical lifters, pushrods and rocker arms. The fuel lift pump is
mounted on the injection pump and draws fuel from the tank. It incorporates a
hand primer pump that is used the bleed the fuel lines of air (e.g. after
filter replacement). Diesel fuel is fed to the injection pump after passing
through a filter. The injection pump delivers fuel under pressure to the
injectors via rigid injector pipes of equal length. On engines fitted with
BOSCH injectors excess fuel is returned to the fuel tank by a metallic spill
pipe interconnecting the injectors. A flexible spill hose is used on engines
fitted with TDZ injectors. Depending on
application, the injection pump is fitted with a pneumatic or centrifugal
governor that controls the amount of fuel injected according to engine load.
Certain versions feature an automatic timing device that advances the timing
of the pump with increasing engine speed. Engine lubrication is
provided by an oil pump driven by the camshaft. Oil is drawn from the sump
and directed into the main oil gallery after being filtered by a fine mesh
strainer or cartridge-type filter. Oil is fed to the crankshaft and camshaft
bearings via small bores. From the front camshaft bearing, oil continues to
the rocker shaft pedestals and cylinder head through external oil lines. The
rocker arm bearings and pushrods are lubricated by oil flowing through hollow
rocker shafts. Cylinder bores, piston pins and timing gears are
splash-lubricated. Two pressure relief valves are fitted to the oil circuit.
The main circuit features a relief valve that opens at 8 bar, protecting the
engine against excessive oil pressure. The oil filter is equipped with a
valve that opens at 2 bar allowing oil to by-pass the filter should it be
clogged. Most installations feature an electrical or mechanical gauge to
monitor the engine's oil pressure. The injection pump and
cooling water pumps have their own oil supply and are not connected to the
main engine lube circuit. However, modern replacement water pumps feature
sealed-for-life bearings and require no maintenance. Engine temperature is
controlled by means of a belt-driven coolant pump, a radiator or heat
exchanger and a thermostat. OM636 RECONDITIONED ENGINES Engines to be
reconditioned are completely disassembled and chemically cleaned. The engine
block and cylinder head are pressure-tested and oil galleries cleaned. Any
damaged studs on the block or head are renewed. Cylinders are bored
and honed to accommodate new pistons. Crankshafts are checked, reground and
polished. New matched conrods with improved lubrication grooves for the
gudgeon pins are fitted. Crankshaft and camshaft bearings are systemically
replaced. The camshaft and timing gears are checked and replaced if
necessary. The timing cover is fitted with a new engine-hour counter. A new
oil pump and pickup pipe are installed before mounting the sump to the
crankcase. Cylinder heads are
refaced within the recommended tolerance or replaced and equipped with valve
guides incorporating valve stem seals. Inlet and exhaust valves are also
replaced if required. New valve springs are systematically fitted and valve
seats checked. Precombustion chambers used are of the latest design. The cylinder head is
fitted to the crankcase and new valve lifters installed. Pushrods are checked
and replaced if necessary. The rocker shafts and arms are carefully examined
and any components showing signs of wear are replaced. New external oil lines
and pressure relief valves are connected to the oil circuit. New gaskets and
seals are used throughout the rebuild. All
engines are test-bench run on a dynamometer for several hours to confirm
power output, oil pressure and exhaust emissions at all operating
temperatures. Engines are usually supplied on an exchange basis, stripped of
manifolds and electrical ancillaries i.e. without starter motor, alternator
and glow plugs. Engines are however fitted with fuel injection equipment and
a new water pump that allow them to be test-run. Customers buying an engine
are always invited to attend whilst their engine is running on the
dynamometer after rebuild. A computer printout describing all engine
operating parameters can be supplied on request. In order to protect
the engine from external corrosion, especially important for the alloy
components fitted, engines are etch-primed and painted prior to crating.
Although engines are usually supplied painted metallic green, customers may
specify any colour at time of order. We are being
increasingly asked to dress our rebuilt engines with new or refurbished
marine ancillaries such as BOWMAN heat exchangers, JABSCO sea water pumps,
starter motors, alternators, hoses and pipework etc.. This service provides a ready-to-fit marine engine. If this is of interest,
please ask for further details. We can arrange prompt
door-to-door collection and delivery Our reconditioned
engines are fully covered by a 12 months back-to-base warranty. OM636 SPARE PARTS AND REBUILD KITS Our stocks include: ENGINE CRANKCASE,
FRONT COVER AND OIL SUMP Reconditioned, rebored
crankcases CYLINDER HEAD Bare cylinder heads,
new and reconditioned Complete built-up
cylinder head assemblies, new or reconditioned to include valves,
precombustion chambers and injectors as required Valve guides CRANKSHAFT AND
PISTONS Standard-size
crankshafts TIMING EQUIPMENT Camshafts DIESEL FUEL
INJECTION EQUIPMENT Reconditioned BOSCH PES4A50
and TDZ PE4A50 fuel injection pumps FUEL FILTER Fuel filter elements MANIFOLDS Inlet manifold casting
ELECTRICAL
EQUIPMENT Series glow plugs ENGINE LUBRICATION Oil pumps ENGINE COOLING Fresh water pumps with
fitted pulley MARINISATION PARTS Vacuum pipe from
injection pump governor to throttle body Engine oil cooler kits
Operating and service
instruction booklets To subscribe to our
mailing list to receive technical and parts bulletins for this engine, please
send a message indicating your email address. So whether you need a
gasket or a replacement engine - contact us to discuss your requirements. Nous parlons français. Wir sprechen deutsch. |
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Click below to see
an OM636 engine sitting on our testbed |
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