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[duffy]

Hi just signed up need some advice!  my omega keeps losing water,i've had a test to see if the head gaskets have gone one garage said yes another said no. i have no loss of power and it only loses water when the better half drives it! any advice ?

[Marks DTM Calib]

Ok, I have split this question out to a seperate topic to get better exposure.

Coolant loss, a few questions:

1) Does the wife always turn the climate temperature up?
2) Any sign of water on the deck when left stood
3) How much water loss, a small mount over many miles or a the header tank emptied in a few minutes.....

As for diagnosis, I suspect a leaking heater bypass valve and hence question 1). IF its a small amount of loss it could be a weaping seal or gasket in the valley.

Headgasket is a long shot on coolant loss with a V6.....very unlikely.

[duffy]

Hi mark DTM calib,

1) climate temp stays around lo to 18/19
2)haven't noticed any water on ground
3)filled up with 3.5litres last week in one go but that was after a short trip and yes the header tank did empty and seemed to be under a lot of pressure .
   the sunday just gone i drove to london and back round trip 115 miles and no problems .
i did have a  problem with somthing leaking at the rear of the engine bay, behind the block small black plastic thing. but i put in some radweld that seems to have solved that problem.

[Dazzler]

Radweld The small black thingy is the HBV-heater bypass valve. I hope the radweld has not blocked part of this unit...

[duffy]

what does the hbv-heater by pass valve do

[Dazzler]

What it says......if no heat required the valve moves and bypasses the heater system.

[Marks DTM Calib]

You need to ask the wife if she is truning the temp up as.

The bypass vale shuts off the flow of water to the heater matrix so the aircon work better.

And radweld wont fix this sort of thing, if its leaking, it needs changing (not to hard to do)

[duffy]

do we need to take the big silver thing off the top of the engine to replace this and would this give false readings on a test to see if the head gaskets are gone?

You need to ask the wife if she is truning the temp up as.

The bypass vale shuts off the flow of water to the heater matrix so the aircon work better.

And radweld wont fix this sort of thing, if its leaking, it needs changing (not to hard to do)

[Marks DTM Calib]

It would depend what test was carried out in order to determine if the head gaskets are failed.....the fact that 50% of the garages said it was ok tends to sudgest it is ok (its VERY rare for them to fail on the V6).

You can do the bypass valve by simply removing the scuttle cover where the wipers are (not hard) but, removing the plenum (large silver bit) makes it even easier.

Radweld is not going to work on a valve as it moves which will disturb the gunk thats trying to do the sealing.

[duffy]

next and hopefully last silly question were is the best place for spares?

It would depend what test was carried out in order to determine if the head gaskets are failed.....the fact that 50% of the garages said it was ok tends to sudgest it is ok (its VERY rare for them to fail on the V6).

You can do the bypass valve by simply removing the scuttle cover where the wipers are (not hard) but, removing the plenum (large silver bit) makes it even easier.

Radweld is not going to work on a valve as it moves which will disturb the gunk thats trying to do the sealing.

[Marks DTM Calib]

They sell the bypass valve in some motor factors (and on ebay) but, we have recently seen these non-gen items failing so I would recommend going to a dealer to get one because:

a) They are known quality parts
b) If they fail within 12 months you get a good warranty.

Do check its this first (sounds like this has already been done) by bunging the heating on Hi and seeing how fast the coolant goes down!

And make sure you re-fill the coolant system with a 50:50 antifreeze/water mix.