M vs MW pump
M vs MW pump
MW is older design, our MW55 the smallest of the MW seize.
The design is stronger for higher pressures, higher specific power (hp/cylinder).
I’d say this IP is more expensive and was replaced (in the passenger car sector) by the cheaper M.
For the 617a the MW is the only turbo IP. There are Ms and (non turbo) MWs on the non turbo 617. Also here the early 617 still had the MW (non turbo).
Element swap and adjustment of a MW is less complicated because for balancing the cylinders (quantity and timing) the barrel has to be turned and shimmed only.
To do this correctly on the M the rollers have to be exchanged in case of different timing. This means measuring the difference and replacing the concerned roller, which means taking out the cam. Common procedure here is not to do this and risk uneven run.
If done correctly this job is time consuming and I bet not every pump is adjusted like that.
The separation of fuel and oil circuit is done by o-ring on MW (barrel/housing) and metal/metal also barrel/housing on M. In case the housing side is damaged on the M the surface has to be redone resulting in a lower position of the barrel which alters the timing. This has to be compensated with a smaller roller…
One big difference is the assembly of the element in the pump. The MW barrel (hardened material) has the thread for the DV holder integrated. So the forces are within the barrel only. Forces here are sealing and fuel pressure.
On the M these forces go via the (alu cast) housing and it sometimes happens that the barrel deforms and the plunger gets stuck when the DV holder is tightened. Also there is the sensitive alu thread in the housing.
This might be the reason why the MW can handle higher pressure.
Due to the design the elements for the MW are more expensive and alternative seizes are rare.
Tom
Just from technical side:
MW is older design, our MW55 the smallest of the MW seize.
The design is stronger for higher pressures, higher specific power (hp/cylinder).
I’d say this IP is more expensive and was replaced (in the passenger car sector) by the cheaper M.
For the 617a the MW is the only turbo IP. There are Ms and (non turbo) MWs on the non turbo 617. Also here the early 617 still had the MW (non turbo).
Element swap and adjustment of a MW is less complicated because for balancing the cylinders (quantity and timing) the barrel has to be turned and shimmed only.
To do this correctly on the M the rollers have to be exchanged in case of different timing. This means measuring the difference and replacing the concerned roller, which means taking out the cam. Common procedure here is not to do this and risk uneven run.
If done correctly this job is time consuming and I bet not every pump is adjusted like that.
The separation of fuel and oil circuit is done by o-ring on MW (barrel/housing) and metal/metal also barrel/housing on M. In case the housing side is damaged on the M the surface has to be redone resulting in a lower position of the barrel which alters the timing. This has to be compensated with a smaller roller…
One big difference is the assembly of the element in the pump. The MW barrel (hardened material) has the thread for the DV holder integrated. So the forces are within the barrel only. Forces here are sealing and fuel pressure.
On the M these forces go via the (alu cast) housing and it sometimes happens that the barrel deforms and the plunger gets stuck when the DV holder is tightened. Also there is the sensitive alu thread in the housing.
This might be the reason why the MW can handle higher pressure.
Due to the design the elements for the MW are more expensive and alternative seizes are rare.
Tom
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