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Fuel Injection Pump Changes |
The most conspicuous update to the pump was the replacement of the early engine's 2-plunger injection pump with the later engine's 6-plunger pump, along with all the affected components, i.e., more injection lines and a different intake manifold.
The 189.984 and 189.985 engines had the 2-plunger pump, and the 189.986, 189.987, 189.988 and 189.989 engines had the 6-plunger pump.
However, even within a given engine type, there where
different versions of the injection pump. In fact, in some cases, two otherwise
identical cars, one with an automatic transmission, the other with a
manual transmission, will have different type injection pumps. The pump
type is located on a plate on the side of the pump.
| Bosch
EP/ZEB 2 KL 75 R 12
Mercedes # 003-074-99-01
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Two-plunger pump. The R12 pump was used on all early 189.984 and 189.985 engines with automatic transmissions. |
| Bosch
EP/ZEB 2 KL 75 R 15
Mercedes # 006-074-21-01 or 189-070-00-01
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Two-plunger pump. The R15 pump was used on all late 189.984 and 189.985 engines with automatic transmissions. The R15 pump supercedes the R12 pump. |
| Bosch
EP/ZEB 2 KL 75 R 17
Mercedes # 006-074-26-01 or 189-070-01-01
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Two-plunger pump. The R17 pump was used on all early 189.984 and 189.985 engines with manual transmissions. |
| Bosch
EP/ZEB 2 KL 75 R 18
Mercedes # 006-074-27-01 or 189-070-02-01)
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Two-plunger
pump. The R18 pump was intended to be used on all late 189.984 and
189.985 engines with manual transmissions. There are two different
sources of information that state that this pump was never actually used
in production. The R18 would have superceded the R17 pump.
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| Bosch
PES 6 KL 70/120 R 12
Mercedes # 189-070-03-01 |
Six-plunger
pump. The R12 pump was the only pump used on all versions of the 189.986
engine. The Edition D parts book states that later 189.986 engines had
the R19 pump installed, but cites conflicting engine numbers. All other
sources of factory documentation state that all 189.986 engines used
only the R12 pump. Numerous inspections of existing vehicles support
this conclusion.
Other engines using this pump are: 189.987-x0 (manual transmission) engines up to 000480. 189.987-x2 (automatic transmission) engines up to 000871.
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| Bosch
PES 6 KL 70/120 R 19
Mercedes # 189-070-05-01 |
Six-plunger
pump. The R19 pump was used on:
189.987-x0 (manual transmission) engines from 000481 to 000673. 189.987-x2 (automatic transmission) engines from 000872 to 001412. 189.988-x0 (manual transmission) engines up to 000238. 189.988-x2 (automatic transmission) engines up to 001456. 189.989-x0 (manual transmission) engines up to 001012. 189.989-x2 (automatic transmission) engines up to 001467.
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| Bosch
PES 6 KL 70/120 R xx
Mercedes # 189-070-07-01 |
Six-plunger
pump. The "R" number of this pump is not yet determined (the
factory documentation does not identify it). This pump was used on the
following engines:
189.987-x0 (manual transmission) engines from 000674. 189.987-x2 (automatic transmission) engines from 001413. 189.988-x0 (manual transmission) engines from 000239. 189.988-x2 (automatic transmission) engines from 001457. 189.989-x0 (manual transmission) engines from 001013. 189.989-x2 (automatic transmission) engines from 001468.
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The two styles of injection pump are completely different, including the various components attached to the outside of the pumps. However, I want to point out a specific component and that is the pump's water thermostat housing.
The housing can rust out and need replacement. This by itself is no problem, as long as the original thermostat element and spacers are reused. What does happen, though, is that the replacement housing is taken from the wrong style pump, i.e. a housing from a six-plunger pump is used on a two-plunger pump, and vice-versa. This causes the two water spigots to be pointed in the wrong directions and generally results in some very creative methods of getting the water lines reconnected.
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Thermostat housing on a 2-plunger pump. The two spigots for the water lines come off at different angles. Note the orientation of the base flange. |
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Thermostat housing on a 6-plunger pump. The two spigots for the water lines come off at the same angle. Note how the orientation of the base flange differs from that of the 2-plunger pump version. |