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[kevinp58]

can it be like the oil cooler?  coolant mix related 

[chrisgixer]

No chance

Nothing happening , so turned the heater control to COLD and out it poured.

[chrisgixer]

Oh hang on, do you mean the oil has eaten the plastic or rubber components in the cooling system?

Yes, there's a good chance of that actually

(Sorry )

[chrisgixer]

From one of my old posts.

Pic shows the valve centre, the valve is opened by vacuume, so when open the flow is exposed to the membrane, if the brown membrane breaks it will leak. Presumably cold ac means vacuume applied and it phishes all over the floor.
...or which ever way round it is, maybe the vac is applied constantly...?

When flow is diverted away from the membrane, it will probably dribble a bit then evaporate off before it shows on the floor.

(...,by cutting the bastward thing in half. MWAAAHAHAHAAA.)

Some innards if anybody is interested.


And this is where mine leaked. Hole pointed out by the screw driver.


So I guess the internal lower brown seal failed.

[05omegav6]

Potentially repairable then

Any one want to send me their dead ones...

Obviously not that one though Chris

[Andy H]

My first car had done 130K when I bought it and there was a receipt for an HBV in the glove box. Car carried on to 200K without another failure.

The HBV on this car failed at 170K. The old one was held on with a cable tie so guessing it had been changed once before.

[chrisgixer]

Potentially repairable then

Any one want to send me their dead ones...

Obviously not that one though Chris

Depends, ime. Sometimes they split, sometimes along a moulding line, so leak regardless of the heater setting. There's more than one failure mode.

But, if it is the brown membrane and/or the brown washer or whatever its called around the centre brass shaft failed as seems likely in this case, I imagine the top with the vac nipple just clips in/out to get at them. Unless it's glued as well.

[chrisgixer]

Actually, looking more closely  

If the brown membrane fails it would leak vacuum.

If the brown washer fails, it would leak coolant.

[05omegav6]

Vacuum failure would simply mean it would stop working. Seam failure ought to be repairable, and that lower seal could perhaps be replace with a stack of soft washers

[chrisgixer]

It's (washer) quite a complex shape, I doubt it would be possible to find the parts, and if available what's the odds of it lasting much longer before another failure mode gets it, like the body splits?

For the agro, I'd just stick a new one in tbh.

[05omegav6]

Just treat as a service item and change with the coolant regardless

[chrisgixer]

Stick one in the boot, next to the crank sensor, (alternator ) etc as parts of the emergency spares supply.

It's not a great problem if it fails, due to the height it's installed at provided its on its post. Any water leak will only lower the water level to the height of the leak.

So if the hbv was installed at, say, the level of the radiator drain plug it would completely empty the system of water. But, as it's installed above the majority of the cooling system, it only leaks to the point that the coolant warning comes on or soon after. So water will still be circulating.

I've driven a fair few miles with a failed hbv, and I must say I don't understand why the system didn't over heat, due to de pressurising if nothing else. But other than the coolant warning, and the puddle in the floor, all seemed normal.

[tidla]

I have a feeling that Chris, after viewing some of your posts that you do like to dissect things.

Ever fancied a job on "body of proof" or similar??

[chrisgixer]

I have been accused of angle grinding anything in sight.

But this was a hacksaw, hence the blue on the edges from the blade. Quite a neat job I thought?