I plan to R&R the water pump on my '83 240D in the near future. Can anyone explain to me why the various procedures I look at (example MBz job 20-210) all show photos pointing to the water pump housing bolts as the ones to remove. One even shows rotating the harmonic balancer so that a recess in it allows access to one of those bolts. Am I wrong in assuming the task is simply removing the pump from the housing while leaving the housing in place?

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Okiebenz

Unless you find the housing pitted from cavitation or damaged in some other way, there is usually no need to remove the housing. So yes you are right in most cases.

However while there you may want to replace the short piece of hose that runs from the thermostat housing to a leg of the water pump housing, and I believe that will require the removal of one of the two housings. Thermostat or water pump.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

When I did my 240D one of the water pump bolts broke so I had to pull the housing too. If you're lucky you can pull just the pump.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

For me, the hardest part of this job was removing the fan bolts. You need a 6 point 10mm box end wrench with the nose ground down a bit to take them off. One of mine rounded off just trying to use a regular wrench.

I did not need to take the housing off, just the pump itself. Haynes has a fairly good account of this job as well.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Thanks to all for the responses. Good input & things to be aware of. My Haynes manual was actually the one that raised the most question in that it inidcates to definitely remove the entire housing/pump assembly.

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Okiebenz

I removed the housing b/c the water pump was stuck in it and I couldn't easily break it free. With the whole assembly on my benchtop, I was able to separate them. I don't think it made the job any harder or easier really. (Later had to re-remove the water pump again, but left the housing in place - the job was about the same).

I used the Factory supplied 10mm wrench to get the fan bolts off. no problem with stripping the heads or anything, but man that is definitely the worst part of the job.

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

What does this factory wrench look like?

I had to grind down the neck on a Craftsman with a Dremel.

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JWJ
1983 MB 300D - > 430,000 miles - Deep Blue - Bilstein Comforts - 0-60 in 24 seconds - 27MPG
1985 MB 300TD (wagon) - > 275,000 miles - Manila Beige - Thule rack - 0-60 in 18 seconds - 22 - 25MPG
Biodiesel, Mobil Delvac 1, and Viton fuel lines!