bad water pump?

[Guest Anonymous]

I've got a 1976 de-smogged Ca car that likes to run hot. It has a new 320i radiator and I tested the thermostat which is functioning correctly (I've also tried both an 80 and 75 degree thermostat). The problem is that there is no coolant moving in the radiator or anywhere else in the system. The water pump appears to be original but it isn't leaking. Could the vanes have eroded away so that it's not moving any coolant? I know the other possibility is the coolant passages in the block are coroded but a water pump would be a lot easier to deal with.

Thanks, -Chris

[Mike Self]

1. Is the thermostat installed correctly? (they can be installed upside down)

2. Are you getting heat from the heater? If not, there may be a big air bubble in the cooling system that's inhibiting coolant flow. Check archives for how to "burp" a cooling system to get the air out.

3. Grab the fan (engine off, of course) and see if you can rock the blades axially. Any play there will indicate failing w/p bearings. This will or is causing leaks--look at the weep hole, positioned at 6 o'clock on the pump body (you'll need a small mirror). If you see a drip or a white, chalky residue trail, the pump is leaking and will fail soon.

4. The pump impeller is cast iron, and I've not heard of one on a 2002 either eroding to nothing or coming loose from its shaft, but I supposed it could happen. Just not with the same frequency that it does on E36s.

5. Is your pump/alternator drive belt good and tight, so that it's not slipping at speed? And do you have the "tropical" five blade (offset blades) fan?

Check these out and report back...

mike

[wagnerf15]

Old water pumps can get REALLY hard to turn (bearing failure, etc) and slip on the belt. This will, on occasion, cause the fluid to circulate much more slowly than normal . They really aren't that hard to check/replace.

[CharlieG]

You can pick up a replacement pump for 50 bucks from most online parts houses, or hell, even Advance auto parts. If you "think" it's original, why risk it to a 30+ year old part?

-Charlie

[c.d.iesel]

Could the vanes have eroded away so that it's not moving any coolant?

yes - but the errosion occurs on the aluminum housing that

the pump attaches to - increasing the gap between the pump blades

and the housing - causing loss of pressure - you wont be able to tell

untill the pump is removed.

I know the other possibility is the coolant passages in the block are coroded but a water pump would be a lot easier to deal with??.

0r your radiator has blocked passages

or your ignition timing is grossly off