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[Marks DTM Calib]

Be aware that on pre-facelift cars the aux pump runs when ever the ignition is on to increase heat up times in the cabin (there was no cabin residual heat option on the early setup)

[Muroman]

Be aware that on pre-facelift cars the aux pump runs when ever the ignition is on to increase heat up times in the cabin (there was no cabin residual heat option on the early setup)

Well That explains why it's on all the time. Now i need to think why it's in wrong flow direction....

[Marks DTM Calib]

From memory, the connection to the HBV goes into the nose of the pump and the feed to the heater matrix (bulk head connection, top) is from the side due to the fact its an impeller pump

Your drawing suggests that the t-piece pipe connects to the HBV, heater matrix return pipe and the pump, is that correct?

Usually its to the HBV (lower from memory) connection, heater matrix return (lower connection) and the coolant return pipe from rad (stainless pipe to the rear of block).

[Muroman]

From memory, the connection to the HBV goes into the nose of the pump and the feed to the heater matrix (bulk head connection, top) is from the side due to the fact its an impeller pump

Your drawing suggests that the t-piece pipe connects to the HBV, heater matrix return pipe and the pump, is that correct?

Usually its to the HBV (lower from memory) connection, heater matrix return (lower connection) and the coolant return pipe from rad (stainless pipe to the rear of block).

The nose of the pump goes to heater matrix, I have double checked that now.

Yes the drawing is right, it goes to lower connection of the heater matrix but it just goes trough the pump.


So I think that the electric pump is going to be removed or then put under manual switch because:

In situation where the HBV is vacuumed it doesn't matter which way the pump is pumping it's either creating a pressure or then underperssure to the heater matrix and HBV. . Am I right?

When the HBV is not vacuumed then there could be the pump pumping but only pumping out of the heater matrix because if it would pump against the heater matrix there would be two ways going in.... Am I right?


Also the pre heater that I'm going to install will work just fine pumping into the heater matrix because then the HBV is not vacuumed and the water can go to engine trough HBV... I am right, am I?

[frostbite]

If the heater matrix is connected to the lower port, you'll get hot air on the cold setting and cold air on the hot.

I have done it, and wasted the cup full or so of coolant then having to remove the 2 pipes again to correct it

[Muroman]

If the heater matrix is connected to the lower port, you'll get hot air on the cold setting and cold air on the hot.

I have done it, and wasted the cup full or so of coolant then having to remove the 2 pipes again to correct it

I'm sorry can't understand this?
If I force warm coolant with pump to the heater matrix lower connection, happens what you said? or what did you mean?

[frostbite]

If the valve is connected upside down it will work opposite to what you set the heater dial/ climate control to, so hot becomes cold and vice versa

[Kevin Wood]

Also the pre heater that I'm going to install will work just fine pumping into the heater matrix because then the HBV is not vacuumed and the water can go to engine trough HBV... I am right, am I?

Yes, that should be OK. Pre-heated coolant will circulate through both the heater matrix and engine block, which is what you want.

[Muroman]

Also the pre heater that I'm going to install will work just fine pumping into the heater matrix because then the HBV is not vacuumed and the water can go to engine trough HBV... I am right, am I?

Yes, that should be OK. Pre-heated coolant will circulate through both the heater matrix and engine block, which is what you want.

Okay, thanks. It's all clearing up step by step

If the valve is connected upside down it will work opposite to what you set the heater dial/ climate control to, so hot becomes cold and vice versa

Which valve you are talking here? HBV?

[frostbite]

Yes hbv, there are 2 ports on one side

All im saying is to not to mix them up when reinstalling

[Muroman]

Yes hbv, there are 2 ports on one side

All im saying is to not to mix them up when reinstalling

Okay, yes I'll be careful:)

[Muroman]

HBV never shuts all the way to specific position, there is always a little flow to everywhere at least that is what happens when the HBV is out of car and tested with under pressure pump.

When normal situation, water flows trough the upper and when under pressure flows trough the lower.

It's just that my HBV doesn't always go back to normal situation 
As able to confirm that when engine stop, ignition on, heater set to high and also some blow set sometimes the car cools down quickly and sometimes not at all.
So does it mean HBV broken or could it be the controlling that doesn't always open the HBV?

[frostbite]

When the car has been switched off there is still a vacuum present which has enough power to keep the pressure in the system albeit for a short while.

I dont have climate control but when mine is off and I turn the direction dial, you can hear the flaps hissing then the vacuum dissapears.

Have you checked the rubber couplers on the vac lines?
any signs of cracking will contribute to vacuum loss

I have a line that has nearly worn through where it has been rubbing on the coolant bridge.

Or the diaphram in you hbv is nearing its usefulness and needs replacing

[Muroman]

When the car has been switched off there is still a vacuum present which has enough power to keep the pressure in the system albeit for a short while.

I dont have climate control but when mine is off and I turn the direction dial, you can hear the flaps hissing then the vacuum dissapears.

Have you checked the rubber couplers on the vac lines?
any signs of cracking will contribute to vacuum loss

I have a line that has nearly worn through where it has been rubbing on the coolant bridge.

Or the diaphram in you hbv is nearing its usefulness and needs replacing

I have checked all lines in engine bay and only thing worries me is that the pipe coming from brake servo (big round thingy) has been rubbed against AC line and has little worn but I think it's still okay. I have moved it a bit and now it doesn't touch that AC line anymore.

HBV is the next in line then but when pumping it with under pressure pump it sure works very good, and my pump doesn't even go on scale when the HBV already works.