27 replies to this topic

[Boab]

Hi guys,
Sorry for bringing this back to the top, but makes sense to keep this here.
I'm using an MPi engine on my supercharged EFI engine but using side mounted radiator. (No header tank)
Question is about water flow.
With the top radiator hose being next to the thermostat, how does the water flow initially with the stat closed?
My setup is top hose to radiator, bottom hose to pump with take off to heater, from heater to left hand side cylinder head.
How does the water from this point get back to the top hose without the stat being open, in my head, does this not cause back pressure?

[KTS]

with the stat closed there is no flow - at least through the top hose into the radiator.  if the heater valve is open water can still flow through the heater circuit and back into the pump intake

[Ethel]

There was a time when engines didn't have water pumps. Water circulated by gravity because cooler water is more dense so will sink in a radiator. That's why old vintage cars had tall radiator grilles. Obviously a modern cooling system is designed to work with a pump, but there'll still be some "thermal syphoning" that can move water through thermostat bleed holes & past sensors.

 

Mechanical water pumps are just simple impellors, water will be drawn in through the gap between the blades & the casing if there's none supplied via the hose connection.

 

An efficient cooling system is a hot cooling system. More heat flows from coolant to atmosphere the higher the temperature differential. That's the biggest advantage of using a pump to force the flow around faster than gravity will.

[nicklouse]

Why no header tank? You need one or you will blow the system.

[Boab]

Why no header tank? You need one or you will blow the system.

Read the initial post mate, I have a side mounted radiator so no header tank is needed, these are only needed for front mount as the radiator is lower than the thermostat housing 👍

[Boab]

with the stat closed there is no flow - at least through the top hose into the radiator. if the heater valve is open water can still flow through the heater circuit and back into the pump intake

Perfect 👍 👌
I'm not using a heater valve, the system is on permanently via the left cylinder head water tap

[Ethel]

That's how the A Series was plumbed up in Metros & why there's a hose (4) in the diagram in the original post (as well as an arrow pointing in the wrong direction).

[nicklouse]

 

Why no header tank? You need one or you will blow the system.

Read the initial post mate, I have a side mounted radiator so no header tank is needed, these are only needed for front mount as the radiator is lower than the thermostat housing

 

But the mini rad has a built in header. So you are running a header tank rad rather that a side mounted rad without a built in header.

[KTS]

 

with the stat closed there is no flow - at least through the top hose into the radiator. if the heater valve is open water can still flow through the heater circuit and back into the pump intake

Perfect
I'm not using a heater valve, the system is on permanently via the left cylinder head water tap

 

 

I had mine plumbed in the same way, but found i was struggling to keep the temperatures down in hot weather.

 

The fix i used was an AN10 to 5/8" barb fitting to the radiator so i could run the cylinder head take-off through the radiator rather than feeding the hot water straight back into the block (in hindsight an AN8 to 1/2" barb fitting would probably have been a better choice)

 

 

i then found that i needed to add a restrictor into the pipework as with unrestricted flow it was overcooling

[Boab]

Why no header tank? You need one or you will blow the system.

Read the initial post mate, I have a side mounted radiator so no header tank is needed, these are only needed for front mount as the radiator is lower than the thermostat housing

But the mini rad has a built in header. So you are running a header tank rad rather that a side mounted rad without a built in header.

Oh behave.
I'm running a pre MPI setup with a MPI engine because I need the sensors for the supercharger.
ie, running the same setup as my MK1

[Boab]

with the stat closed there is no flow - at least through the top hose into the radiator. if the heater valve is open water can still flow through the heater circuit and back into the pump intake

Perfect
I'm not using a heater valve, the system is on permanently via the left cylinder head water tap

I had mine plumbed in the same way, but found i was struggling to keep the temperatures down in hot weather.

The fix i used was an AN10 to 5/8" barb fitting to the radiator so i could run the cylinder head take-off through the radiator rather than feeding the hot water straight back into the block (in hindsight an AN8 to 1/2" barb fitting would probably have been a better choice)



i then found that i needed to add a restrictor into the pipework as with unrestricted flow it was overcooling

Nice idea, I'll keep this in mind, cheers 👍

[Spider]

 

Why no header tank? You need one or you will blow the system.

Read the initial post mate, I have a side mounted radiator so no header tank is needed, these are only needed for front mount as the radiator is lower than the thermostat housing

 

 

Not exactly sure what you are referring here as a 'header tank', but there's no way I'd run any A Series without one, sometimes referred to as a expansion or overflow tank.

[Boab]

Why no header tank? You need one or you will blow the system.

Read the initial post mate, I have a side mounted radiator so no header tank is needed, these are only needed for front mount as the radiator is lower than the thermostat housing

Not exactly sure what you are referring here as a 'header tank', but there's no way I'd run any A Series without one, sometimes referred to as a expansion or overflow tank.

Yes, expansion tank. These were never fitted to pre MPi engines and to be honest, I've never seen one fitted to any pre MPi. Have you got examples of this expansion tank fitted on A series please (apart from MPi)
I knew this would cause an issue.