Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[geoffr70]

Hello, further to my recent post about HBV, what exactly goes wrong with it? Mine is definitely leaking, I put my hand round and it was soaking underneath it, it wasn't hot though. My new one came today, going to fit it tomorrow along with drivers exhaust manifold gasket, but what exactly fails on HBV? It doesn't like like something that takes a great deal of stress or works particularly hard. Thanks

[Andy B]

Hello, further to my recent post about HBV, what exactly goes wrong with it? Mine is definitely leaking, I put my hand round and it was soaking underneath it, it wasn't hot though. My new one came today, going to fit it tomorrow along with drivers exhaust manifold gasket, but what exactly fails on HBV? It doesn't like like something that takes a great deal of stress or works particularly hard. Thanks

The diaphragm perishes. 

[geoffr70]

Doh, seems obvious now you've told me! Thanks Andy B!

[skyblue]

andy, quick question for ya, Ive been having to top up  water every other wk as its dropped well below the half way mark on the tank....would you say this is where my leak is?

[Andy B]

andy, quick question for ya, Ive been having to top up  water every other wk as its dropped well below the half way mark on the tank....would you say this is where my leak is?

could be .....  :-/ Have a look around the back of the driver's cylinder head with the heater and a/c set at various positions. When mine last went, it was OK wghe the a/c was OFF but leaked when in AUTO  :-?  :-?

[skyblue]

Thanks will have closer look  and see if I can find a damp spot as ive never noticed anything (wettness) under the car where its been parked

[Abiton]

Hello, further to my recent post about HBV, what exactly goes wrong with it? Mine is definitely leaking, I put my hand round and it was soaking underneath it, it wasn't hot though. My new one came today, going to fit it tomorrow along with drivers exhaust manifold gasket, but what exactly fails on HBV? It doesn't like like something that takes a great deal of stress or works particularly hard. Thanks

The diaphragm perishes. 

Surely there's more to it than that?
The way I see it, vacuum moves a diaphragm, that moves some sort of actuator, that changes the flow of coolant via some sort of valve.
 If it were just  the diaphragm perishing, wouldn't that just result in it failing to change state, rather than leaking?

 :-/

[Andy B]

....
 If it were just  the diaphragm perishing, wouldn't that just result in it failing to change state, rather than leaking?

 :-/

that appeared to be the case with mine, you could see it preished alongside the centre spindle  :-/  :-/

[Andy H]

....
 If it were just  the diaphragm perishing, wouldn't that just result in it failing to change state, rather than leaking?

 :-/

that appeared to be the case with mine, you could see it preished alongside the centre spindle  :-/  :-/

A perished diaphragm would weep coolant but still exert enough force to operate the valve.

If it was badly perished enough to fail to actuate the valve then most of the coolant in the engine would be sucked into the inlet manifold in about 5 minutes 
[edit]I haven't cut one in half (yet). I was assuming that the diaphragm acts as the seal. On reflection it is probably designed with a diaphragm to actuate the valve stem, a seal on the valve stem to keep the coolant in and a gap between the two so that leaking coolant doesn't get drawn into the engine.

Maybe the perished diaphragm and leaking seal are both (independent) side effects of ageing  :-/ [/edit]