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Well, it's like this... I've had no end of grief recently with my EWP installationon my 9000CS, not cooling properly, me blowing up the controller, getting too hot etc etc (EWP= Electric Water Pump)
I've also had some very good advice from Abbott about how to make things run cooler (I might do a brief write up in while...)
Meanwhile though, I've still got the EWP and no mechanical water pump- and I have to drive the car and the weather is due to be warm for the next few days. Tonight I was trying to track down the cause of the air that always seemed to be drawn in to the pump, and indeed which I reckon could be the cause of cavitation at higher rpms in the mechanical pump... and found it!!
With the EWP running at max, air is drawn in through the small bore pipe that runs from the radiator to the expansion bottle. If I clamp it tight, no air is drawn in and the pump therefore flows much more water.
It appears the vacuum presented by the pump does a better job of sucking down the pipe leading to it from the header tank than the radiator! I'm also quite coinvinced that if it happens with the EWP flat out, it will also happen with the mechanical pump at higher engine speeds, hence the cavitation reported by Abbott...
So, the question is, what exactly is the small bore pipe for? If I clamp it off, will I get any problems? I can see that it might be used for some sort of pressure equalisation in a standard system fitted with a stat but as I don't have a stat any more this shouldn't be a problem. I can also see that it is a route for any air that develops in the system to migrate out of the radiator.
I've also had some very good advice from Abbott about how to make things run cooler (I might do a brief write up in while...)
Meanwhile though, I've still got the EWP and no mechanical water pump- and I have to drive the car and the weather is due to be warm for the next few days. Tonight I was trying to track down the cause of the air that always seemed to be drawn in to the pump, and indeed which I reckon could be the cause of cavitation at higher rpms in the mechanical pump... and found it!!
With the EWP running at max, air is drawn in through the small bore pipe that runs from the radiator to the expansion bottle. If I clamp it tight, no air is drawn in and the pump therefore flows much more water.
It appears the vacuum presented by the pump does a better job of sucking down the pipe leading to it from the header tank than the radiator! I'm also quite coinvinced that if it happens with the EWP flat out, it will also happen with the mechanical pump at higher engine speeds, hence the cavitation reported by Abbott...
So, the question is, what exactly is the small bore pipe for? If I clamp it off, will I get any problems? I can see that it might be used for some sort of pressure equalisation in a standard system fitted with a stat but as I don't have a stat any more this shouldn't be a problem. I can also see that it is a route for any air that develops in the system to migrate out of the radiator.