Water pumps - 6 blades vs 8 blades

[dave_aber]

Hi, Having finally traced a very minor coolant loss to the waterpump using UV dye, I swapped my orinal pump for one I bought ages ago when I replaced the rad, but never got round to fitting.

Now I have it fitted, the van is running 6°C or so hotter (cyl. head temp) and is really sensitive to "a damn good thrashing".

Previously, it would sit at 88° or 89° all day, and rise a wee bit to around 94° on long fast hills etc.
Now, it sits between 92°-95°, and quickly rises to 99° if pushed. I dare not drive with as much enthusiasm as before, or I'll be seeing 3 figures on the head temp.

I've bled it twice, and I'm not getting any air out, so I'm happy it's bled OK

So, (I should have checked before fitting) I have just pulled the new pump out, and it's an 8-blade impeller, with small straight / flat blades.

The original had 6 larger, curved blades.

Is this a common issue, where the 'modern' (dare I say cheaper?) pumps have less water-moving ability?



New (left) and old (right)

[Northern Bongolow]

i changed mine and saw a 2 deg rise in coolant temp (not metal temps). old one 6 blade, new I THINK IS 8 blade.

ive got muzzes old pump here, we recently swapped for a gen mazda one----- old one 6 blade, that had a few miles on it . not sure how many on a gen mazda one. (lushprojects doesnt show the impeller.

[dave_aber]

I'm tempted to see if my local ford dealer has one for a ranger, to see what the impeller looks like.

[Northern Bongolow]

i dont know if that would prove anything dave, smaller system etc.

in fact that may be the problem.
6 big blades for bongo, 8 small for ranger. .

as the seller always says, it'll be right. . but on a border line system. .

i pressure tested my first v6 at the bash, measured while running.
the normal running pressure was 0.9. put a 8 blade on that then see if it fizzzzes. i dare not run it up to fans on low or high.