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[MV6Danny]

3.5 litres is a lot to loose, there'd be steam out the exhaust like the orient express.

I'd say the hbv is leaking in either hot or cold position. Depending on the CC setting used when the water was lost....?

Some light scum on the surface of the coolent is not unusual, ESP if the coolent is old.


Might be worth getting the coolant level warning fixed too.

does mine have a coolant level warning and how would i fix it?

Would have thought so. My 99 cdx had coolant level warning. Hbv and oil coller cover plate tested it regular as well.

Head cracks are not even remotely common on the v engine. It's not that.

Coolant will leak and then not leak from the hbv depending on settings.

Grumpy running could be a number of things unrelated. Ht issues. Air lake. Sticky icv. Did the coolant loss start at the same time as the rough running?

Was the coolant level monitored after the service?

I dont know as i didnt check the coolant level when it started running rough on start up just assumed it needed new plugs and leads. and no didnt monitor the level after the service. After the initial start up the car runs and ticks over fine.

[feeutfo]

Pressure test is a good idea too. But may still give false results if the hbv is leaking in its cold/ac on position, but the test is done when hbv is in the hot position, for instance.

 But anyway, I'd also go with the topping up and monitoring after or during every journey. Top it up, keep water bottle full in the boot. Drive it round the block, check the level. Top up of empty, change the climate setting, drive, check etc. see what the failure mode is. Any water under the car etc. feel under hbv for (hot) water. And son on.

If the hg is gone, which I doubt, Then it's too late to worry about anyway. Is the oil a normal oil colour?

[MV6Danny]

Pressure test is a good idea too. But may still give false results if the hbv is leaking in its cold/ac on position, but the test is done when hbv is in the hot position, for instance.

 But anyway, I'd also go with the topping up and monitoring after or during every journey. Top it up, keep water bottle full in the boot. Drive it round the block, check the level. Top up of empty, change the climate setting, drive, check etc. see what the failure mode is. Any water under the car etc. feel under hbv for (hot) water. And son on.

If the hg is gone, which I doubt, Then it's too late to worry about anyway. Is the oil a normal oil colour?

I will monitor it. the oil is fine no mayo in it on the dipstick. the hg failed on the firering on my mfl 2.5 and that ran really bad after it went sometimes failing to start or even turn over. but nothing like that yet. will have to try and pressure test it somehow. 

[MV6Danny]

what about the smell from the expansion tank then? is that normal?

[feeutfo]

what about the smell from the expansion tank then? is that normal?

Do you have any spare coolent left over from the service? If so does the stuff in the bottle smell the same? Are you aware of the original smell? What coolent is in it, is it vx red?
I'm not sure coolant tank smell is enough to condem hg tbh.

[MV6Danny]

yes i do have some left and it is vx red. i will have a sniff tomorrow but tbh it is a very strong petrol smell in the expansion tank. cant remember what it smelt like when i changed the coolant. will check everything again tomorrow and post an update. Thanks Chris 

[Andy H]

When a cylinder fires the hot, partially combusted, petrol/air mixture reaches a pressure of several hundred psi momentarily. If you have very early stage failure of a fire ring it is possible for hot gases (containing unburnt petrol) to pass one way but not coolant in the other direction (or very little).

You are now aware that there is a potential problem. Fix the level sensor and make sure that the coolant bottle remains topped up. Odds are that it is a faulty HBV or small leak somewhere else. Even if you are looking at the worst case scenario it will probably several thousand miles before you need to do anything about it.

[Kendo1690]

When a cylinder fires the hot, partially combusted, petrol/air mixture reaches a pressure of several hundred psi momentarily. If you have very early stage failure of a fire ring it is possible for hot gases (containing unburnt petrol) to pass one way but not coolant in the other direction (or very little).

You are now aware that there is a potential problem. Fix the level sensor and make sure that the coolant bottle remains topped up. Odds are that it is a faulty HBV or small leak somewhere else. Even if you are looking at the worst case scenario it will probably several thousand miles before you need to do anything about it.

Ive had the same problem with my 2001 2.2 and have been told that due to petrol smell and brown scum plus slight leak from the header tank area,it's the hg,but on reading this I'm now having 2nd thoughts.Also can someone tell me what a hbv is please.

[RobG]

When a cylinder fires the hot, partially combusted, petrol/air mixture reaches a pressure of several hundred psi momentarily. If you have very early stage failure of a fire ring it is possible for hot gases (containing unburnt petrol) to pass one way but not coolant in the other direction (or very little).

You are now aware that there is a potential problem. Fix the level sensor and make sure that the coolant bottle remains topped up. Odds are that it is a faulty HBV or small leak somewhere else. Even if you are looking at the worst case scenario it will probably several thousand miles before you need to do anything about it.

Ive had the same problem with my 2001 2.2 and have been told that due to petrol smell and brown scum plus slight leak from the header tank area,it's the hg,but on reading this I'm now having 2nd thoughts.Also can someone tell me what a hbv is please.

Heater Bypass Valve. Lives at rear of engine, controls flow of heated coolant to matrix for interior cabin heat.
http://www.omegaowners.com/forum/index.php?topic=90574.0

[Entwood]

Given the proximity of the header tank to the engine,fuel inlet pipes and other bits and bobs; and as most engines are to some extent or other, dirty with old oil/fuel/gunge of various denominations ...  "smell" tests are notoriously unreliable .... IMHO .. I certainly would not condemn a HG purely on the basis of smell ....   

[Kendo1690]

Given the proximity of the header tank to the engine,fuel inlet pipes and other bits and bobs; and as most engines are to some extent or other, dirty with old oil/fuel/gunge of various denominations ...  "smell" tests are notoriously unreliable .... IMHO .. I certainly would not condemn a HG purely on the basis of smell ....   

Unfortunately it's just been broken in the last 2 days so it's a tad to late,doh,but going to put bits on eBay,