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[BgBLizard]

Hi All

I am hoping someone can help me as I have spent sometime trying to fix my Pre facelift 3.0 V6 Mega but have failed so far.

Problem:
Over heats after going about 6miles, lots of steam, it has got progressively worse as it used to do 15miles when I first noticed this.

Symptoms:
Coolant pipes fit to burst.
Radiator stone cold except on ends.
Both fans running flat out.
Engine warms normally thermostat opens water circulates through radiator evenly, fans kick in out normally temperature gauge seems to read correctly but as you drive it gets to a point the coolant seems to stop flowing and it over heats.

Checked so far:
Replaced thermostat twice.
Checked water pump, this has a metal impeller and is firmly attached to the pulley, seal is good.
Radiator flushed, de scaled no sign of sludge or blockage,
Cabin heater works fine.
On this site I found mention of the heater bypass valve but I do not know where this is and how it works so I haven't checked it.

Finally I did a compression test and one cylinder was down so I suspected a blown head gasket, I removed the head only to find that the gasket looks good (I'm not an expert). I now have a car in bits with no sign of a resolution and would really appreciate some help.

Thanks in advance.

Andy

[Welung666]

De ja vue! I'm sure I've just read this on Vxon

[tunnie]

Hi All

I am hoping someone can help me as I have spent sometime trying to fix my Pre facelift 3.0 V6 Mega but have failed so far.

Problem:
Over heats after going about 6miles, lots of steam, it has got progressively worse as it used to do 15miles when I first noticed this.

Symptoms:
Coolant pipes fit to burst.
Radiator stone cold except on ends.
Both fans running flat out.
Engine warms normally thermostat opens water circulates through radiator evenly, fans kick in out normally temperature gauge seems to read correctly but as you drive it gets to a point the coolant seems to stop flowing and it over heats.

Checked so far:
Replaced thermostat twice.
Checked water pump, this has a metal impeller and is firmly attached to the pulley, seal is good.
Radiator flushed, de scaled no sign of sludge or blockage,
Cabin heater works fine.
On this site I found mention of the heater bypass valve but I do not know where this is and how it works so I haven't checked it.

Finally I did a compression test and one cylinder was down so I suspected a blown head gasket, I removed the head only to find that the gasket looks good (I'm not an expert). I now have a car in bits with no sign of a resolution and would really appreciate some help.

Thanks in advance.

Andy

Sounds like the rad is blocked, its stone cold in the centre?

Has it ever had radweld in it?

[ians]

Unlikely to be the head gasket, more likely blocked rad I would say,  or a major air lock, but this is unlikely as you have obviously refilled the coolant several times.

HBV is the black plastic cylindrical device the size of a can of peas behind the drivers side of the engine under the scuttle.  For 30 quid its worth changing.

Were you losing significant coolant?

[BgBLizard]

Thanks all for the quick responses

I have had the rad out and it dose pass water readily so I did not suspect this. Also it seems to work normally for some time heating all over until the fans cut in.
I will not dissmiss it but it's expensive so is there away of testing it once and for all.

It has not lost any coolent except when it boils :-)

[tmx]

sounds like a blocked radiator!

HBV lives at the rear of the block behind the ECOTEC Breather pipes if thats gone you will be loosing water in a drip drip drip fasion from the rear of the engine

if youve overheated the engine then damage may of already been done ie Headgaskets maybe lucky though.......

wheres you location?

[BgBLizard]

Thankyou
Yeovil Somerset

[BgBLizard]

Have just checked there are just two pipes off the bridge between the cylinder heads that go through into the heater matrix so no HBV ?

[tunnie]

Have just checked there are just two pipes off the bridge between the cylinder heads that go through into the heater matrix so no HBV ?

If someone fcking muppet has removed that, no wonder its over pressizing!

[tmx]

http://www.omegaowners.com/forum/YaBB.pl?num=1193594464
There be a guide with pics on how to replace the HBV thatll give you an idea of what to look for!

[ians]

Do you not have AC?  (police spec per chance..??)
In that case there would be no HBV.

[BgBLizard]

Yep sorry it is an ex Police demo so no goodies what so ever

[feeutfo]

lots of steam after 6 miles...? Where is the steam coming from? Filler cap should hold 13psi in the system. Sounds like its not holding pressure and boiling over....

(er.... nervous finger over post button as not good with over heating issues. Never had the problem personally)

[BgBLizard]

Thanks, also forgot to say i bought a new cap which had the effect of letting go sooner than the old one.

[ians]

worth checking the the expansion tank doesn't have a micro crack in it?