Mechanical pump and auxiliary pump
Turbo Mini Forums

Hi

Just wondering if any knows if the mechanical water pump would allow flow when it's not turning.

I've fitted a electric pump which I switch on after engines shut down to try and stop heat soak.
The turbo water return is to a copper pipe that I've soldered in the top of the rad. When the engine is running I can see water shooting into the rad from the turbo (with cap off)
But when I turn the engine off and turn my electric pump on, there's no water going through the turbo. Which is annoying as that's the main reason I fitted the auxiliary pump.

The pump I fitted is a bosch pump that is rated at 12 liters per minute.

Any thoughts on why it's not working as I planned?

Thanks,
Josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

The impellor will only spin when the pulley is turning, with the engine off you'll barely get anything past it

I was thinking that nick.
So basically a auxiliary pump is a waste of time unless you run a electric pump as main pump.

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

As far as I can guess yeah, although you can configure the main electric pump to run on after shut down so need for the aux one

Yes that is true. So auxiliary pump is a complete waste if time lol.

Oh well. Not sure I want to run a electric pump instead of mechanical. Is there much power saved/gained by doing so?
Will it cool better than the mechanical pump as it'll be pumping more water at idle and lower revs?

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

There should be some movement around the a series water pump because ifs not in a very good housing a fair bit of room in thee. I could be wrong. But couldn't you just rig up a small rad and cooling system just for the turbo?

Rubbish! If the impellor wasn't a good fit then the pump wouldn't move any water it would just be a shitty propellor.

Some pumps are just shitty propellers.

I can't see why the pump wouldn't flow when it's static.

Josh, I had another pump rigged up coming off the heater take off then going through a small radiator before going through the turbo then finishing off going into a sandwich plate on the stat housing and this worked well on a timer relay once I turned the engine off. I have a temp sender in line after the turbo which did show the temp drop so there was getting some flow. But because the pipe from heater take off loops up a little higher than the side mounted radiator it sometimes was prone to air locking once the engine stopped pumping.
Roy B

Hmm

I'm really debating fitting a electric water pump to do away with the mechanical pump.

At the moment I have a tee coming off of the dry deck 180° hose going to the auxiliary pump, then out of the pump to the extra rad from a 125cc scooter. From the rad back to the bottom hose. I'm running a minispares 2core rad with a unerversal electric fan sucking through it. No mechanical fan.
Need to get some sort of ducting to seal it off at the back.

It runs at about 85°c-90°c which I think is a tad hot.
I've just removed the thermostat and fitted a sleeve. Not tested this yet. If this doesn't work I might try and mount the rad to the inner wing and make some kind of duct as ive seen done on here.

If that doesn't make much difference then I might do away with the mechanical pump and fit a electric one in its place.


Josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

The standard water pump is a very crude centrifugal pump.

A centrifugal pump offers little resistance to flow (either way) when stationary as the flow is induced by centrifugal force off the vanes, not any clearance or tolerance issues. The flow path is straight through the vanes from inlet to outlet so when stationary it's just a kind of curved path between the vanes of the impellor.

That's why industrial sized centrifugal pumps setup in pairs or more for standby reasons have to have non return valves to stop a running pump pushing all its flow back through a shutdown one.

The Mini one if it has the cast impellor has some restrictions because the casting design of the impellor is crap. If it's a pressed tin one, there is no restriction.

Your problem is elsewhere.

Schrödinger's cat - so which one am I ???

Ok
Had a bit of a think.

Would it be OK to feed an extra rad (small 125cc scooter rad) from the heater take off on the head if I'm running dry deck? Or would it effect the water flow across the head?

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985