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[Sixstring]

Can anyone tell me how much of a pig of a job changing the HBV on my miggy is?   Flushed matrix, no HGF, oil level and water level ok, reset heater unit, tried blocking up the vacuum pipe to HBV, no effect, and now clutching at straws. Before I replace the water pump and thermostat,and fill the block with flush/caustic soda weak mix I'd better do the lot as STILL no heater and its bloody FREEZING on a morning, and I can't clear the screen.

Cheers!

Mike.

[TheBoy]

Scuttle off, its doable, but bit fiddly.  Same with plenum removed.  Scuttle and plenum off makes it much easier. Still fiddly mind

[sjc]

You can also remove the entire wiper motor assembly in under 5 minutes and that makes access much better.

Just remember to put it back before anything else!!

[Sixstring]

This being the case, BEFORE I attempt this, is there any way to condemn/confirm it is actually buggered before I start??

[RobG]

 When heat is called for via the controls the "valve" in the unit operates via a vacuum solenoid behind the glovebox allowing hot water to pass through the hoses into the matrix. So the theory is, if heater controls are switched off, hoses to matrix should stay cold or just lukewarm. When you call for heat are the bulkhead hoses to matrix getting hot

[sjc]

I understood it to be the opposite way round so that the air-con switches the heater HBV to bypass the heater matrix when cooling is required.

The problem of an HBV stuck in "bypass" happens when the air-con has not been on (or off I suppose) for a while and the valve gets a build up of crap causing it to become sticky.  Then when the air-con is used, the vacuum is strong enough to switch the valve but afterwards, the spring behind the valve disc is not strong enough to "unstick" it and it stays in "bypass" mode.

If you could hit it with something, it might free it off but also might break it cos they're only plastic! 

I'd say the only way to check it properly is to remove it and see for yourself if it's seized but you could reverse the hose connections on the side with the 2 stubs and see if you get heat then - you should be able to do it without too much coolant loss.

[Entwood]

Pull the thin lead off the top of the HBV .. that is the vacuum control .. and stick a screw in it to prevent a vac leak. This will then leave the vacuum connection on the HBV open to atmosphere .. ie  NO VAC .. this is the "HEAT"  setting (vac turns off heat) ... see if you then get any hot water flow from the HBV.

When mine was playing up it took a little while for the HBV to "move"  internally .. I was about to give up when heat suddenly started. I have a new HBV waiting to be fitted, system presently running in the "disconnected" state and nice and warm ...

My theory (waits to be shot down) is that the HBV was/is "sticking" internally .. as I could get heat first start up .. but if then switched off and left for 5 minutes on restart I could only get cold. I realise it COULD be a dodgy climate controller ... but I won't find out until I install the new HBV .... (and thats waiting for a warmer day when I do a whole load of jobs at once ... HBV, Breathers, Cam Covers, oil change).

[sjc]

Pull the thin lead off the top of the HBV .. that is the vacuum control .. and stick a screw in it to prevent a vac leak. This will then leave the vacuum connection on the HBV open to atmosphere .. ie  NO VAC .. this is the "HEAT"  setting (vac turns off heat) ... see if you then get any hot water flow from the HBV.

When mine was playing up it took a little while for the HBV to "move"  internally .. I was about to give up when heat suddenly started. I have a new HBV waiting to be fitted, system presently running in the "disconnected" state and nice and warm ...

My theory (waits to be shot down) is that the HBV was/is "sticking" internally .. as I could get heat first start up .. but if then switched off and left for 5 minutes on restart I could only get cold. I realise it COULD be a dodgy climate controller ... but I won't find out until I install the new HBV .... (and thats waiting for a warmer day when I do a whole load of jobs at once ... HBV, Breathers, Cam Covers, oil change).

I'd say if you're getting vacuum to the HBV when heater controls are at hot then you defo have a dodgy vac solenoid or dodgy climate controller.  Should be an easy test with a voltmeter on the solenoid to see if it's being told to do the "wrong" thing.

[covey]

I have a 2001 2.2CD in which I have been freezing my balls off for the past three months.  My aircon works perfectly and gets very cold (too cold!!) I get no heat at all from any vent even on Hi with the climate control. Temp guage shows water temp to be normal at all times (90 degrees?)

Have flushed system and replaced anti-freeze and replaced external air temp sensor.. When I first noticed the lack of heat (Nov) I found that if I took revs up to 6k for a minute, I got warm air until I switched off, then back to cold.

Have bought new HBV to install but cannot find any post which indicates where HBV is to be located on 2.2 Omega.  Also, where is the thermostat to be found?  Life was earier with my first Triumph Herald. None of this hi-tec computery business!!