Hi! I'm new here, and I love driving and customizing my 320i. I'm replacing my entire cooling system and I was wondering...what is the most effecient water pump available for a 1983 320i? And if anyone knows where I can buy it, that info would be good too. Thanks.

There are two types of water pumps, one has a stamped steel impeller the other has a cast iron impellor. The steel impeller deteriorates pretty quickly so the cast impeller is the way to go. I changed my water pump when I got the car-the pump was a steel impeller and it was toast, the PO included a new cast iron impeller pump with the car. I don't know who sells them so you would need to shop around. Maybe someone on the forum knows a source.

ken

The OEM.

I dont think there is one more effecient than another,
Flushing your entire cooling sytem to get rid of any crud.
is time well spent.

Ken is right. I didn't realize that the m10 pump had the stamped vs cast issue.

Ken is right. I didn't realize that the m10 pump had the stamped vs cast issue.

Yeah me either. I just gont mine from BavAuto when I rebuilt the motor and dont remember which one it was.

Looks like the GMB one is a stamped steel. The Graf and Hepu look like they have the cast iron. With the Meyle I can't tell, the picture only shows the outside. Since that Meyle fuel filter I got before I have steered clear of Meyle's products.

that's good to know...I think the few pumps i've had were all made by Graf (so I assumed there was only one type of impeller).

Also, the E30 318i (m10) water pump uses a slightly smaller pulley (it's 107mm vs 136 or 128 found on older m10's). But the 318i pulley & water pump have a rectangular bolt pattern...so you can't directly bolt on the 318i pulley to the 320i water pump (which uses a square bolt pattern).
And I think the S14 water pump can bolt up to the m10 too, but not sure if there's any advantages it may have over the 318i pump.

e23/4/8s used to offer a "tropic kit" for cars in hot areas. Pulleys were one of the items changed.

That info about the steel and cast iron impellers was really useful. I appreciate it a lot.