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[terry paget]

[/img]https://www.dropbox.com/s/ftc2fwijxqiuhw5/VECTRAleak2.jpg?dl=1[/img]
Vectra C 1.8 petrol manual
Found a puddle under this car this morning. Seems to be coming from a metal pipe beneath the thermostat, which then disappears behind the front heat shield. It's a simple joint, torx screws either end, got no excuse to leak now. Does anyone know, is it a flat paper gasket seal, or an O-ring?

[terry paget]

pic of leaking joint

[dave the builder]

looks like a flat fiber gasket ,but ,as I said before(when you replaced the wet stat), the thermostat housing is prone to cracking
especially if any fixing is over-tightened
a smear of instant gasket on the old gasket should solve a leak from the gasket
it won't solve a leak from a crack in the housing
so examine closely ,torch and magnifying glass is a help 

[Doctor Gollum]

Neither...

It's normal condensation from the aircon system. Ignore it and do something more important 

[Doctor Gollum]

Neither...

It's normal condensation from the aircon system. Ignore it and do something more important 

That said, if it's dripping down to that then it may well be the thermostat seal.

[Sir Tigger KC]

Neither...

It's normal condensation from the aircon system. Ignore it and do something more important 

Terry said he came out this morning to find a puddle.  An aircon condensation drip would have dried up overnight. 

[Doctor Gollum]

Neither...

It's normal condensation from the aircon system. Ignore it and do something more important 

Terry said he came out this morning to find a puddle.  An aircon condensation drip would have dried up overnight. 

Had a further look at the picture, hence my subsequent post

[terry paget]

Thanks for advice, gentlemen. Taste test confirms it is coolant.
Odd it should decide to leak after 11 years service; I reckon Dave could be right, that the housing has cracked. I see on e-bay I can get a thermostat for £15, or a thermostat with housing for £23. The housing assembly will involve more connections, but seems safer route to me. Any comments?

[Doctor Gollum]

Change it as an assembly

[terry paget]

www.ebay.co.uk/itm/FOR-VAUXHALL-INSIGNIA-1-6-VECTRA-C-SIGNUM-1-8-THERMOSTAT-WITH-HOUSING-SENSOR/251437585024
This thermostat and housing assembly has what looks like a coolant connection below the thermostat. I imagined it was an aircon pipe. It seems to go below the thermostat to connect with the heater input hose.

If so, that poor connection could be my coolant loss.

[Doctor Gollum]

www.ebay.co.uk/itm/FOR-VAUXHALL-INSIGNIA-1-6-VECTRA-C-SIGNUM-1-8-THERMOSTAT-WITH-HOUSING-SENSOR/251437585024
This thermostat and housing assembly has what looks like a coolant connection below the thermostat. I imagined it was an aircon pipe. It seems to go below the thermostat to connect with the heater input hose.

If so, that poor connection could be my coolant loss.

If, as that link suggests, the housing is plastic, I would be inclined to change the whole assembly as the plastic is likely to be getting brittle, and therefore leaky

[terry paget]

The thermostat housing is indeed plastic, thus prone to cracking if screws are overtightened.

My theory is that the thermostat housing does not need changing. The leak is the junction between the heater pipe from the block at its connection to the base of the thermostat housing. Do you agree?

[Doctor Gollum]

Not necessarily, that pipe flange could be below the leak...

[dave the builder]

The thermostat housing is indeed plastic, thus prone to cracking if screws are overtightened.

My theory is that the thermostat housing does not need changing. The leak is the junction between the heater pipe from the block at its connection to the base of the thermostat housing. Do you agree?

as I said before(when you replaced the wet stat), the thermostat housing is prone to cracking
especially if any fixing is over-tightened
a smear of instant gasket on the old gasket should solve a leak from the gasket
it won't solve a leak from a crack in the housing
so examine closely ,torch and magnifying glass is a help 

we can't remote examine where the leak is Terry
you can get the housing off and physically look at it 

[terry paget]

Or maybe you think that a crack in the thermostat housing is the cause of the leak in the heater pipe junction. So the cure is to change the thermostat housing.

[dave the builder]

Or maybe you think that a crack in the thermostat housing is the cause of the leak in the heater pipe junction. So the cure is to change the thermostat housing.

my first reply said the housings are prone to cracking
BUT....
only you can see if it's cracked or just a gasket fail

[terry paget]

Agreed. So I may as well obtain a new thermostat and housing assembly now, then dismantle things when I have a spare to hand.
 
Thanks again for your good advice.

[Nick W]

Thanks for advice, gentlemen. Taste test confirms it is coolant.
Odd it should decide to leak after 11 years service; I reckon Dave could be right, that the housing has cracked. I see on e-bay I can get a thermostat for £15, or a thermostat with housing for £23. The housing assembly will involve more connections, but seems safer route to me. Any comments?

£8 difference on an aging part with known problems? Why would you even consider not buying the assembly?

[dave the builder]

Thanks for advice, gentlemen. Taste test confirms it is coolant.
Odd it should decide to leak after 11 years service; I reckon Dave could be right, that the housing has cracked. I see on e-bay I can get a thermostat for £15, or a thermostat with housing for £23. The housing assembly will involve more connections, but seems safer route to me. Any comments?

£8 difference on an aging part with known problems? Why would you even consider not buying the assembly?

I did mention the housing was prone to cracking when Terry first replaced the wet stat ,
and I will say again ,extreme care should be taken not to over-tighten the bolts on the housing,and even torque ,or you stress the housing ,which when it heats up ,can crack
if the original housing is not cracked (just leaking from a Gasket) it may be stronger than the cheap,non OEM replacement 
hence my recommendation to examine it very closely ,with a torch and magnifying glass 

[terry paget]

Thanks to all for advice. On removing the thermostat it was clear from rusty lower screws and the appearance of the thermostat holder face that the thermostat gasket had been leaking (right again Doc), so I merely replaced the thermostat in holder. I drove the car 150 miles yesterday, no coolant loss, and now the heater works.

[Doctor Gollum]