Engine 850: B5204S/2.0/20v: Water pump - Do I fit one?

[V70Zig]

Well not wishing to throw a spanner in the works....but very strange that one tooth is missing after every three ?
Doubt that it would break them off or whatever so consistently, maybe it's not the original pump ? Or the original pump was like that ?
Only someone in the know will know !!!! Or has come across this before.

Good luck with it....

[ITSv40]

Originally Posted by V70Zig

Well not wishing to throw a spanner in the works....but very strange that one tooth is missing after every three ?
Doubt that it would break them off or whatever so consistently, maybe it's not the original pump ? Or the original pump was like that ?
Only someone in the know will know !!!! Or has come across this before.

Good luck with it....

That could well be the case with diesels. All the genuine pumps fitted to petrol engines that I have seen have teeth missing.

[V70Zig]

Originally Posted by ITSv40

That could well be the case with diesels. All the genuine pumps fitted to petrol engines that I have seen have teeth missing.

Well, I couldn't say if it's the case with diesel's and having re read the last few replies all I can say is.....

Moral of the story....don't drink and drive or post when you start drinking early.......

[Moose850]

Originally Posted by V70Zig

Well not wishing to throw a spanner in the works....but very strange that one tooth is missing after every three ?
Doubt that it would break them off or whatever so consistently, maybe it's not the original pump ? Or the original pump was like that ?
Only someone in the know will know !!!! Or has come across this before.

Good luck with it....

Definitely not broken off, the pulley was made like that. It also has Volvo and AISIN cast into the housing.

[Moose850]

Originally Posted by ITSv40

That could well be the case with diesels. All the genuine pumps fitted to petrol engines that I have seen have teeth missing.

This is supposed to be the genuine article but with Volvo ground off the casing as it is not sold by Volvo but is made by the same people that make for Volvo.
https://www.onlinecarparts.co.uk/aisin-2225517.html

The picture does not show the pulley like mine with a missing tooth after every 3 teeth. The question is if I buy this pump and it comes through with the pulley as in the picture it will have 19 teeth whereas if I were to add the 5 missing teeth on my pulley it would equal 20 so if the teeth are the same spacing the pump would run at a different speed, slower I think. Any ideas as to whether this would be a problem?

[Moose850]

Decided to change the water pump in the end and bought genuine water pump for £89 + VAT. You also get the 7 bolts threadlocked. Interestingly the bolts in the pump I took off which was the original (@ 250,000 miles) were at least 10mm longer than the new one's.

Before I did the job there was not water leak and no noise associated with the pump. Once the belt tension was released and I spun the pump by hand there was an awful 'metal to metal' sound and a tad of side play in the bearings.
When I removed the pump the impeller blades had been chaffing on the ali house that they run in within the block. The leading edge of each blade was shiny along it entire length and the housing it runs in was shiny too. Just in the nick of time I would say.

I have a question:
Before the pump change the temp gauge needle run bang on half way (horizontal) and never ever moved in hot or cold weather - just as it should.
Now it is a hairs breadth below half way then a few miles along the road it will be bang on, then a little while later slightly down again. Also the air from the heater is not as hot as it used to be.
I imagine I must still have a little air in the system. Would you say that is correct? If so how can I remove it or is it just a case of time and letting it work itself out?

[ASt85]

Originally Posted by Moose850

I have a question:
Before the pump change the temp gauge needle run bang on half way (horizontal) and never ever moved in hot or cold weather - just as it should.
Now it is a hairs breadth below half way then a few miles along the road it will be bang on, then a little while later slightly down again. Also the air from the heater is not as hot as it used to be.
I imagine I must still have a little air in the system. Would you say that is correct? If so how can I remove it or is it just a case of time and letting it work itself out?

The slightly below mid-point is probably due to the cleaner coolant in the system enabling you to see very small differences that you don't see if you have old dirty coolant - the dirty coolant has a higher specific heat capacity so takes longer to cool, by which time the thermostat is open again.

Whilst the lower temperature may be due to air in the system, the other possibility is again due to the lower heat capacity of clean coolant so less heat comes out of the radiator. If it is due to air, it will purge from the system fairly quickly.

[Moose850]

Originally Posted by ASt85

The slightly below mid-point is probably due to the cleaner coolant in the system enabling you to see very small differences that you don't see if you have old dirty coolant - the dirty coolant has a higher specific heat capacity so takes longer to cool, by which time the thermostat is open again.

Whilst the lower temperature may be due to air in the system, the other possibility is again due to the lower heat capacity of clean coolant so less heat comes out of the radiator. If it is due to air, it will purge from the system fairly quickly.

I was thinking that the new coolant would cool more efficiently therefore 'hold' more heat if you like. I can see what you mean about old rusty sludge would change it's temperature at a slower rate but would not imagine any difference would show on the gauge due to the relatively slow response of the thermostat.
My thoughts are air in the system but I will watch with interest and see if things settle back to as they were before.

Many thanks for your reply.

[ASt85]

Originally Posted by Moose850

I was thinking that the new coolant would cool more efficiently therefore 'hold' more heat if you like.

The clean new coolant will transport less heat but circulate slightly faster so the thermostat has less energy being transmitted to it in a given time so the ability to react is slower.

The corrosion salts and oxides in old coolant increase the coolant's ability to hold heat so more energy is delivered to the thermostat in the given period of time so the thermostat will react more quickly. The old coolant is more efficient at transmitting heat throughout the system but as it is moving more slowly achieves a more even temperature at the temperature sensor so it appears to be a steadier reading.

As you, I think is more likely that the reduced heater output is due to air in the heater matrix.........burp it and I don't mean throw the car over your shoulder and pat it on the back

[Moose850]

Originally Posted by ASt85

The clean new coolant will transport less heat but circulate slightly faster so the thermostat has less energy being transmitted to it in a given time so the ability to react is slower.

The corrosion salts and oxides in old coolant increase the coolant's ability to hold heat so more energy is delivered to the thermostat in the given period of time so the thermostat will react more quickly. The old coolant is more efficient at transmitting heat throughout the system but as it is moving more slowly achieves a more even temperature at the temperature sensor so it appears to be a steadier reading.

As you, I think is more likely that the reduced heater output is due to air in the heater matrix.........burp it and I don't mean throw the car over your shoulder and pat it on the back

Hell, think I have my head around that. So why should we change coolant, because it becomes contaminated and corrosive?

When you say 'burp it', is there anything I can do like squeeze hoses or is it a case of just waiting?