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[robson]

Why cant I see the HBV When I look under the scuttle is it at a lower level .I am trying to feel for a coolant leak but cant find the HBV.I would like to do this without removing the scuttle if possible.Is it slightly left of centre drivers side looking from front of car.

[The Red Baron]

behind drivers side cyl head. 

[Paddy Flannery]

Yes, it is slightly left of centre. Looks like a wee Starship Enterprise. 

[SandBoy]

And an expensive part for a bit of plastic and also a hand scratcher as well!!!!!

[omega3000]

finding it is the easy bit , wait till you come to take off the hose clips  Second time around gets easier 

[Darth Loo-knee]

Easiest way is to remove the plenum and inlet manifold. You can then get access to the hbv without removing the scuttle then struggle... just my opinion of course

[robson]

Thanks Darth wish you were nearer me. Does the position of the air con setting have an effect on a small coolant leak. The leak seems to be variable'

[robson]

What I mean by a leak is a loss of coolant in the bottle I am not sure where the leak is .It is not evident from looking over the hoses etc.

[less]

What I mean by a leak is a loss of coolant in the bottle I am not sure where the leak is .It is not evident from looking over the hoses etc.

Hi Robson, HBV leaks are often intermittent and may be started/stopped by turning heater temp up or down.

[The Red Baron]

What I mean by a leak is a loss of coolant in the bottle I am not sure where the leak is .It is not evident from looking over the hoses etc.

Hi Robson, HBV leaks are often intermittent and may be started/stopped by turning heater temp up or down.

on/off,  valve can leak in either position, some when open, some when closed. 

[chrisgixer]

Thanks Darth wish you were nearer me. Does the position of the air con setting have an effect on a small coolant leak. The leak seems to be variable'

Yes it does, test with ac in high then lo

There should be a vac pipe from the two heater matrix pipes in the bulk head to top of the hbv, of that helps. It may have fallen off its post/peg that's bolted to the back of breather box(iirc) behind cylinder 5

[robson]

Thanks Chris I think that the air con is working ok I am trying to confirm whether it is the HBV leaking before stripping out scuttle or inlet and plenum as suggested by Darth.

[Darth Loo-knee]

Ok. You say you can't see a water leak. Yet your water level is dropping.
start the car with the heater on hi. Leave it running with a torch in hand.. perhaps some paper under the car. once your convinced there is no leak,  turn the heaters down to Lo. Again cheak for the leak with tje torch okus cheak your paper. ..
I dont see any point asking you to check this that and the other yet which will only help to confuse you.

[robson]

Thanks Darth It now seems that with aircon off I get no loss of coolant as I have no water in the footwell,( heater matrix,) does this confirm that it is the HBV at fault.Does water flow through the heater matrix at all times or is it stopped when heater is not required. I will try your paper test where does the aircon condensate relevieve itself, will this confuse findings

[05omegav6]

Clue is in the name Heater Bypass Valve...

Sounds like your coolant loss is predominantly from the heater matrix not the valve if you're getting coolant in the drivers footwell

You probably won't find any coolant under the car...