Hi All,
As above is there a way to test the water pump?
Been having heat issues running around 215°F/100°c.
The thermostat has been replaced but going out to check on placement of arrow which I just found out about.

The pump has no seepage or moisture around it or weep hole.
Will a pump impeller be bad without any seepage?
Thank you in advance.

After inspection of thermostat only a punch mark has been found maybe indicating top.
Suggestions?

You could always just pop the top radiator hose off and see how fast it drains, other than that I don't think there's any way other than pulling the water pump

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1982 300D Turbodiesel, daily driver. Mods so far: Fram 8038 paper filter, 4 brake light mod, Gen II w126 (front) rotors/calipers, boost turned up to 12lbs, non-egr manifolds, water/methanol injection, 4-speed manual
1980 300SD Turbodiesel, project car, nearly ready to hit the street

1974 240D, New paint

One thing to check is the little line coming off the water pump, should be a banjo fitting at either end, it's some kind of pressure bleeder or something and if it gets plugged can cause overheating issues. Also might want to check to see if your yep gauge is working correctly, I use a cheap infrared thermometer gun thing I got at home depot for like $30

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1982 300D Turbodiesel, daily driver. Mods so far: Fram 8038 paper filter, 4 brake light mod, Gen II w126 (front) rotors/calipers, boost turned up to 12lbs, non-egr manifolds, water/methanol injection, 4-speed manual
1980 300SD Turbodiesel, project car, nearly ready to hit the street

1974 240D, New paint