Water Pump replacement

[revjhdavis]

Hi All

I'm hoping you can put my mind at ease. I had to have the water pump replaced last week....I'm too arthritic to do it myself and had to entrust it to my local garage as I live at least 50 miles from a club-recommended garage. I did give him a printout of the method of refilling/bleeding...don't know if he used it though it has mucky prints on it! It's come back and runs fine and there's no water loss or lowering of level in the header tank but, according to my Hadyn sensor mounted on the back of the cylinder head, the engine is running at least 5 deg higher than before. I've checked that the stat is opening but is this ok. I mentioned it at the garage later and they said it was fine and probably due to the pump giving a slightly different flow rate. Are they fobbing me off or can I assume it is fine?

John

[wonkanoby]

might not be

as ive seen some pumps with more impellor blades than others

[Northern Bongolow]

i think i can put your mind at ease----- .
ive got 3 temp monitors on mine and a pressure monitor, low coolant alarm. high coolant alarm.
my water pump went and i replaced it myself and bled it up (ive done this quite a few times,and for others). i noted a similar rise in temps to you and a small increase in pressure, this i put down to the number of impeller blades on the copy pump (lots), the gen mazda pump has a different (fewer ) amount of blades and the shape of them is different.

i conclude that if you have a hotter running bongo in general, then a gen mazda pump is possibly best. ask the garage who swapped the pump if they fit a gen one or a copy.
mine runs fine at the slightly elevated temp, but it is maintained regularly.

[revjhdavis]

NB

Thanks for that, it was a copy rather than genuine Mazda. I'll keep an eye on the temp. Feel relieved

John

[daveblueozzie]

Picture of a genuine water pump and a copy.
copy on the left.
http://i151.photobucket.com/albums/s143 ... 6-1129.jpg

[dave_aber]

I had exactly the same.

Potted history :

1. Original Rad failed - weeping along top crimped join. not uncommon. Replaced with the cheaper option pattern part.
2. About 12 months later, noticed a very slow use of coolant - LCA would sound about once every 6 weeks.
3. Bought a UV Dye kit and torch on eBay. Traced the leak (very quickly) to the waterpump lower tell-tale hole. You can only find this leak with UV really.
4. Replaced the pump. old (original?) pump had 6 big blades, new (pattern) part had 8 smaller blades. Bled the system etc.
5. Instantly noticed a rise in head temp of about 6°C
6. I posted on here asking about it, and it seemed not that unusual.
7. I subsequently went looking about with the UV torch, and discovered that I had a tiny weep from the bottom crimped join on the replacement rad, now about 12 months old.
8. Replaced the rad with a new genuine mazda one (tres expensive).
9. Cyl head now back 6°C lower.

So, I concluded that the pattern pump is 'just' good enough with a good radiator, and not quite good enough with a old (only 12 months) blocked up (didn't look bad when removed and cut open) or otherwise perhaps just less efficient pattern radiator.

Pays yer money etc - except I couldn't find anything other than 8-blade pumps, being sold as genuine.

[The Great Pretender]

Picture of a genuine water pump and a copy.
copy on the left.
http://i151.photobucket.com/albums/s143 ... 6-1129.jpg

Hi Dave, pump efficiency is controlled more by impellor clearances’ than how many blades. The tighter the clearances’ the more efficient it performs. The less free space there is above and below the blades is what matters most.

[dave_aber]

I would agree that the original and copy I had also showed that the original 6 blades as well as being larger in area stuck out of the housing by about 1mm more, so had less clearance with the block waterway.

[revjhdavis]

Thanks to everybody for your insights. I have my Hadyn temperature alarm sensor fitted into the existing bolt hole on the back of the cylinder head and alarm set to 100 deg C.....is this a reasonable setting or could I go a bit higher given the water temperature is now about 5 deg higher?

Thanks

John