So - a side note on water pumps. I won't put a junk water pump in my car, and as such this was quite a search for a new one as i didn't want a Chinese part.

After quite some investigation, and hands on inspection, I was able to see that:

A) The Bosch water pump is now made in China. It used to be USA. All of the samples of this water pump appeared to be horrible. Stamped impeller

B) The GMB water pump was also made in China by a different maker than the Bosch. It had more sharp edges, but appeared to be better made. It used a cast iron vane for it's impeller.

C) Saleri water pump was made in Italy. Easily the best of these three pumps.

D) End users reported having to modify the Graf water pump to get it to work. I'm not certain why, or if the saleri will also need this attention. If so, I will post pics.

E) The Gates pump was also made in China and was blatantly a GMB pump rebranded.

 

Are you sure about this? Why would American Bosch have made anything for this car?

 

I went hands on with 3 of the Bosch pumps at pep-boys. The first one said "Made in USA", the second two said "Made in China".

They all looked to be exactly identical pumps, so they may have all been China and someone just marked box 1 wrong. They were all clearly the appropriate pump for the 3.2L merc. All pumps I have handled appear to be identical at this point.

Added data about the Gates pump.

 

Interesting. Yeah I'm pretty sure the stock one has german writing on it. I'll have to look at my old one.

 

I think that a stamped impeller may be preferable to a cast one, the old cast impellers I've seen were really crude. I have a pump with a stamped impeller and it looks fine to me.

 

My current is a stamped impeller and is the original that came with the motor and has German markings

 

The new saleri was stamped too. I'll bet the stamped impeller.is.easier to .get right.