16 replies to this topic

[dotmatrix]

I have a 998 Metro with a 12g940 head, a GWP187 waterpump, the small waterpump pulley (big one doesn't fit), no head-pump bypass hose, bypass through heater (as is normal on metros), an 88 degree thermostat and a renovated heater.

The problem I have is that in the winter the air out of the heater will only get lukewarm and not really hot and I suspect that this would be improved by using either a small impeller waterpump or the large diameter pulley (that does not fit) or maybe I can fit a smaller diameter crank pulley? Does any of you have experience with this?

Edited by dotmatrix, 05 September 2018 - 08:07 AM.

[nicklouse]

More likely to be an air lock or internally blocked matrix.

[DeadSquare]

It might be worth making sure that the hose from the head goes to the top of the heater.

 

Another thought.   One like this, but check that it will withstand hot water

 

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[nicklouse]

Why would you connect to the top heater connection? All you do is create an air trap.

[DeadSquare]

Not if you turn the tap off on the head, remove the hose and hold it up.

 

The heater fills from the bottom and pushes the air out of the top.

[dotmatrix]

More likely to be an air lock or internally blocked matrix.

Heater matrix is brand new and get very hot in the summer so dont think it is blocked or has and airlock

[dotmatrix]

It might be worth making sure that the hose from the head goes to the top of the heater.
 
Another thought.   One like this, but check that it will withstand hot water
 
Caravan 12v In-Line Water Pump 14 LPM - COMET GEO IN-LINE PUMP

I will check how the hoses connect to the heater. why would it matter in which direction the water flows through the heater matrix?

so your suggestion is to remove the mechanical pump and fit an electric? but how would I know how the flow of this pump compares to the flow of the mechanical?

[gazza82]

 

It might be worth making sure that the hose from the head goes to the top of the heater.
 
Another thought.   One like this, but check that it will withstand hot water
 
Caravan 12v In-Line Water Pump 14 LPM - COMET GEO IN-LINE PUMP

I will check how the hoses connect to the heater. why would it matter in which direction the water flows through the heater matrix?

so your suggestion is to remove the mechanical pump and fit an electric? but how would I know how the flow of this pump compares to the flow of the mechanical?

 

 

I think he means in addition ..

 

Mini heaters generally work ok so something is amiss with your flow ..

[dotmatrix]

It might be worth making sure that the hose from the head goes to the top of the heater.
 
Another thought.   One like this, but check that it will withstand hot water
 
Caravan 12v In-Line Water Pump 14 LPM - COMET GEO IN-LINE PUMP

I will check how the hoses connect to the heater. why would it matter in which direction the water flows through the heater matrix?

so your suggestion is to remove the mechanical pump and fit an electric? but how would I know how the flow of this pump compares to the flow of the mechanical?

 
I think he means in addition ..
 
Mini heaters generally work ok so something is amiss with your flow ..

yes I agree and my thoughts is the flow needs to be lowered, possibly in general and not just through the heater matrix

[DeadSquare]

Like the car rad before the war without a water pump, the water heats in the block, rises through the head, flows to the rad, cools, sinks and returns to the block;   the same is happening in the heater, coming in hot from the head at the top, cooling, sinking and returning to the block.

 

Keep the water pump, you will need it in the summer.  Insert the electric pump in the return between the heater and the block.

 

I did it on a girlfriends Hillman Imp to get more hot water from the engine in the back, so ought tho work on a Mini.

[russo]

Even though you have an 88 degree thermostat it may be opening too early, I suggest you test it or replace it.

[gazza82]

Like the car rad before the war without a water pump, the water heats in the block, rises through the head, flows to the rad, cools, sinks and returns to the block;   the same is happening in the heater, coming in hot from the head at the top, cooling, sinking and returning to the block.

 

Keep the water pump, you will need it in the summer.  Insert the electric pump in the return between the heater and the block.

 

I did it on a girlfriends Hillman Imp to get more hot water from the engine in the back, so ought tho work on a Mini.

 

 

Although it works like that the heater matrix is enclosed so not getting the benefit of air flowing over it to cool it  So it will still be relatively hot/warm when it returns to the engine .. assuming that the heated coolant is getting through. It doesn't sound to me like that is happening.

 

Fitting an electric pump is simply masking the problem .. I used to get cooked in my mate's Mini ... the heater was too good. He eventually ran it with the tap on the heat partly closed even in winter .. although there were one or two days when it was open fully! (I agree it is probably useful on an Imp where the rad is a lot further away from the heater .. but on a Mini the hoses are relatively short.)

[Bat]

Hi,

Is the thermostat fitted in the head or the sandwich plate?

Cheers 

[dotmatrix]

Hi,
Is the thermostat fitted in the head or the sandwich plate?
Cheers

Yes the thermostat is on top of the sandwich plate

[dotmatrix]

And the hot hose is connected to the top heater pipe