Oil Filter: Description and Operation

1 Initial operation filter element
2 Combination filter element

Oil filter
Main and bypass filter elements are contained in a cartridge.

During first inspection (1000-1500 km or 800-1000 miles) the initial operation oil filter element (1) should be replaced by the combination filter element (2).







A combination filter element
Dimension A = 40 mm
B Combination filter element
Dimension B = 55 mm

The combination filter element should then be replaced during oil change every 7500 km or 5000 miles.

Attention!
On this engine, install only the combination filter element (6) with the larger main flow filter component (dimension "b" = 55 mm).

Operation
The oil filter comprises the following main components:

a) Oil filter housing with bypass, return flow locking valve and thermostat.
b) Cap with return flow pipe, check valve and sealing ring.
c) Combination filter element.







1 Nut
2 Stud
3 Cap
4 Sealing ring
5 Oil filter housing
6 Thread connection
6a Thread connection
7 Compression spring
8 Bypass valve
9 Valve seat bypass valve
10 Compression spring
11 Thermostat
12 Control valve
15 Compression spring
16 Return flow locking valve
17 Valve seat return flow locking valve
18 Return flow pipe
19 Check valve
20 O-ring
21 O-ring
22 Riser
23 Connection for oil pressure gage (model 116 and 123)
24 Oil filter element bypass filter component
24a Oil filter element main flow filter component
25 Rubber seal
A Uncleaned oil toward air-oil cooler
B Uncleaned oil from air-oil cooler
a From oil pump
b To bearing points
c Finely filtered oil for oil pan
d Oil return flow bore toward oil pan

Coming from oil pump via feed duct (a). the oil enters the oil filter housing at return flow locking valve (16) and flows directly to combination filter element up to an oil temperature of approx. 110 °C.

After flowing through combination filter element the oil, which has been cleaned in main flow filter component (24a), flows via riser (22) and duct (b) to main oil duct and on to bearing points.

On the other hand, the oil, which has been finely filtered in bypass filter component (24) flows through return flow pipe (18) and duct (c) toward oil pan.

To make sure that main flow and bypass flow remain separated from each other, the combination filter element is provided with a rubber seal (25).







a From oil pump
b To bearing points
c Finely filtered oil toward oil pan
e To exhaust gas turbocharger
f To oil pressure gage (models 116 and 123)

Starting at an oil temperature of approx. 110 °C the thermostat (11) starts to displace control valve (12), which arrives at its end position at approx. 125 °C. In end position, the direct flow toward combination filter element is locked except for a given quantity of oil (g). This quantity of oil is enough to guarantee lubrication of engine at low outside temperatures, when continuous flow in oil cooler is widely obstructed by viscous oil.

The larger oil quantity flows to air-oil cooler and is cooled there, it will then flow back to oil filter housing and flows through oil filter element from outside in inward direction.

The cleaned oil flows through riser (22) or return flow pipe (18) to bearing points or to oil pan.

Attention!
On engine 617.950 (model 116) a 95 °C thermostat has been installed in oil filter up to engine end No. 019718. Here, thermostat control starts at approx. 95 °C and ends at approx. 110 °C.







A Uncleaned oil toward air-oil cooler
B Uncleaned oil from air-oil cooler
a From oil pump
b To bearing points
c Finely filtered oil toward oil pan
e To exhaust gas turbocharger
f To oil pressure gage (models 116 and 123)
g Oil quantity directly to combination filter element







8 Bypass valve
a From oil pump
b To bearing points

If the oil filter element is badly contaminated and the differential pressure between the contaminated side and the clean side of the filter exceeds 3.5 bar, bypass valve (8) will open. The oil will then flow uncleaned toward engine and exhaust gas turbocharger.







a From oil pump
b To bearing points
e To exhaust gas turbocharger
f To oil pressure gage (models 116 and 123)

Return flow locking valve (16) and check valve (19) in return flow pipe (18) prevent the oil from flowing out of oil filter back into oil pan with the engine stopped for an extended period.

When renewing oil filter element, unscrew cover (3) and pull up a bit.

The return flow pipe (18) attached to cap will then expose a bore which connects ducts (a) and (b) to each other. The oil in oil filter will flow through duct (c) into oil pan.







Models 116 and 123
(engines 617.950/952)

The exhaust gas turbocharger is provided with the oil required for lubrication and cooling by way of a line (arrow) on rear oil filter cover.







The oil return flow from exhaust gas turbocharger to oil pan proceeds at outside of engine (arrow).