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[Jim Bob2]

Does anybody know the what the 2 way water valve does at the back of the engine thats a pig to get to, and what its proper name is because mine is leaking and I need to order a new one. It has a vacuum pipe on it by the looks of it.

[Markjay]

Does anybody know the what the 2 way water valve does at the back of the engine thats a pig to get to, and what its proper name is because mine is leaking and I need to order a new one. It has a vacuum pipe on it by the looks of it.

If it's the Heater Bypass Valve (HBV) you are referring to, then it stops hot coolant from circulating through the cabin when the A/C is switched on...

[Markjay]

It’s secondary function is to splash hot coolant all over the DIS, which is equally difficult to get to, so that the Vx engineers at Elsmere Port can chuckle when they think of us trying to replace eth HBV only to do the same again when the DIS pack-up as result of water ingress two weeks later…  

[Jim Bob2]

Does anybody know the what the 2 way water valve does at the back of the engine thats a pig to get to, and what its proper name is because mine is leaking and I need to order a new one. It has a vacuum pipe on it by the looks of it.

If it's the Heater Bypass Valve (HBV) you are referring to, then it stops hot coolant from circulating through the cabin when the A/C is switched on...

Yes that would figure because it's not leaking as much when the aircon is on and one of the pipes that comes off it goes through to the cabin.
Thanks.

[Jim Bob2]

Does anybody know the what the 2 way water valve does at the back of the engine thats a pig to get to, and what its proper name is because mine is leaking and I need to order a new one. It has a vacuum pipe on it by the looks of it.

If it's the Heater Bypass Valve (HBV) you are referring to, then it stops hot coolant from circulating through the cabin when the A/C is switched on...

Yes that would figure because it's not leaking as much when the aircon is on and one of the pipes that comes off it goes through to the cabin.
Thanks.

Whats the DIS ?

[TheBoy]

Actually, I think it was decided that it prevented coolant from entering the heater matrix when only cold air is requested. But thats splitting hairs

[Markjay]

Does anybody know the what the 2 way water valve does at the back of the engine thats a pig to get to, and what its proper name is because mine is leaking and I need to order a new one. It has a vacuum pipe on it by the looks of it.

If it's the Heater Bypass Valve (HBV) you are referring to, then it stops hot coolant from circulating through the cabin when the A/C is switched on...

Yes that would figure because it's not leaking as much when the aircon is on and one of the pipes that comes off it goes through to the cabin.
Thanks.

Whats the DIS ?

DIS = Distributorless Ignition System – that’s the bit at the back of the engine where all the HT leads from the spark plugs go into…

[rpont]

Actually, I think it was decided that it prevented coolant from entering the heater matrix when only cold air is requested. But thats splitting hairs

I don't really think it's splitting hairs, you just beat me to it. It shuts off the coolant when the heating is off. That IS different to what was said earlier and unless we get it right we are bound to have someone saying 'my HBV is open when I've got the aircon on to demist'.

I do understand why people get it wrong though. You all have that luxurious ECC and have never heard the valve click when you turn both heater comtrols to off  

[Markjay]

You may very well be right - AFAIK the HBV is only fitted to cars with A/C, which is why is seemed to me that it would cut-off the heating to the cabin when the A/C is on... but if anyone knows better then so be it...

[rpont]

You may want to use the A/C to demist in the winter but still want to heat the incoming air. It's to stop the heating fighting the air conditioning when you don't want heat. When I got my car the aux water pump below the expansion tank wasn't plugged in and it was some months before I saw the motor without a connection and asked the dealer. During that time the aircon would start to cool and as the engine warmed up it lost it's efficiency. I felt the heater pipes once and they were boiling hot to my hand. Without the pump running convection heated them up I suppose. Once the dealer found the lead and plugged the pump in it was ice cold in the cabin when the heating was off and A/C on.

I've said all of this to show that if the matrix is hot the amount of heat it chucks out does affect cooling even if you are not directly pulling air through it. Someone on the dark side said he has a GLS without aircon and he does have an HBV.

[Markjay]

You may want to use the A/C to demist in the winter but still want to heat the incoming air. ...

This is not possible on the facelift due to the new Climate - in order to get the A/C on, I need to set the temp down otherwsie it does not kick-in - and the temp setting is also common to the heater so it blows cold air. iirc I use to be able to do this on my previous pre-facelift whcih had A/c (not Climate)...

[nixoro]

Someone on the dark side said he has a GLS without aircon and he does have an HBV.

Wonder if there is any truth to that?

[Markjay]

Someone on the dark side said he has a GLS without aircon and he does have an HBV.

Wonder if there is any truth to that?

Yeah yeah, I know a guy who knows someone who has a friend that....  

Seriously, no idea, both my Omegas had A/C...  

[rpont]

This is not possible on the facelift due to the new Climate - in order to get the A/C on, I need to set the temp down otherwsie it does not kick-in - and the temp setting is also common to the heater so it blows cold air. iirc I use to be able to do this on my previous pre-facelift whcih had A/c (not Climate)...

I thought the ECC ran the compressor all the time unless you selected ECO. That may be with the pre-facelift one, I don't have that luxury on mine  

[Markjay]

This is not possible on the facelift due to the new Climate - in order to get the A/C on, I need to set the temp down otherwsie it does not kick-in - and the temp setting is also common to the heater so it blows cold air. iirc I use to be able to do this on my previous pre-facelift whcih had A/c (not Climate)...

I thought the ECC ran the compressor all the time unless you selected ECO. That may be with the pre-facelift one, I don't have that luxury on mine  

No, when ECO is off the compressor cut-in and out as needed, so will not cut-in during the winter. When ECO is on, it will not cut-in even if needed. This is why you need to set it down to LO from time to time during the winter with ECO off and let the A/C run to prevent leaks...