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[j3lly]

Y26
MPG has recently dropped suspect CTS
Have bought a genuine genuine GM replacement for AutoVaux which is pale blue
But the one coming out believed genuine GM is off white
Is this a problem
Does the colours mean anything

Thanks

[dave the builder]

if you cross reference the part number, the same sensor can be dark blue,light blue,grey or black ,depending on manufacturer
lots of people quote "genuine GM" or OEM 
GM buy from many suppliers

reading your fault codes and getting live data ,fuel trims ,CTS signal voltage ,lambda voltages etc etc will help pinpoint the cause of lower MPG
the CTS is only one of many parts that can lower MPG

[j3lly]

if you cross reference the part number, the same sensor can be dark blue,light blue,grey or black ,depending on manufacturer
lots of people quote "genuine GM" or OEM 
GM buy from many suppliers

reading your fault codes and getting live data ,fuel trims ,CTS signal voltage ,lambda voltages etc etc will help pinpoint the cause of lower MPG
the CTS is only one of many parts that can lower MPG

Thanks for taking time to reply
So colours of CTS don't matter
The reason I suspect CTS is car seems to running at a lower temperature according to gauge
Was around 90'/95' now 80' / 85' so suspect over fuelling
I have basic diagnostics which report no errors
I also have a set of spark plugs on the way
I fit them all and see what happens

[Andy B]

...
 car seems to running at a lower temperature according to gauge
Was around 90'/95' now 80' / 85' so suspect over fuelling ....

A stuck open 'stat will cause a car to run too cool. 

[dave the builder]

if you cross reference the part number, the same sensor can be dark blue,light blue,grey or black ,depending on manufacturer
lots of people quote "genuine GM" or OEM 
GM buy from many suppliers

reading your fault codes and getting live data ,fuel trims ,CTS signal voltage ,lambda voltages etc etc will help pinpoint the cause of lower MPG
the CTS is only one of many parts that can lower MPG

Thanks for taking time to reply
So colours of CTS don't matter
The reason I suspect CTS is car seems to running at a lower temperature according to gauge
Was around 90'/95' now 80' / 85' so suspect over fuelling
I have basic diagnostics which report no errors
I also have a set of spark plugs on the way
I fit them all and see what happens

vauxhalls over fuel badly when cold in my experience

A stuck open wet thermostat COULD allow coolant to the rad early with the engine not up to 92 degree  optimum running temp.

the Omega dash temp gauge has a separate sensor to the engine CTS , so which is telling lies  or are both correct ,and something else(like a stuck open wet stat)causing lower MPG  hence the need for live data and methodical tests   

but replacing parts "willy nilly" without proper diagnosis and tests is a slippery slide .

[dave the builder]

...
 car seems to running at a lower temperature according to gauge
Was around 90'/95' now 80' / 85' so suspect over fuelling ....

A stuck open 'stat will cause a car to run too cool. 

beat me to it 

[biggriffin]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

[Andy B]

...
 car seems to running at a lower temperature according to gauge
Was around 90'/95' now 80' / 85' so suspect over fuelling ....

A stuck open 'stat will cause a car to run too cool. 

beat me to it 

[dave the builder]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

+ clean all the breathers, change the plugs,check the coil packs,clean the throttle body etc
them pesky plenum things being in the way of all the bits you want to get at 

[biggriffin]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

+ clean all the breathers, change the plugs,check the coil packs,clean the throttle body etc
them pesky plenum things being in the way of all the bits you want to get at 

Might as well do can covers and cam belt while your at it 

[STEMO]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

+ clean all the breathers, change the plugs,check the coil packs,clean the throttle body etc
them pesky plenum things being in the way of all the bits you want to get at 

Might as well do can covers and cam belt while your at it 

Just throw a new engine in....while you're there like. 

[dave the builder]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

+ clean all the breathers, change the plugs,check the coil packs,clean the throttle body etc
them pesky plenum things being in the way of all the bits you want to get at 

Might as well do can covers and cam belt while your at it 

Just throw a new engine in....while you're there like. 

and replace the body ,transmission,brakes,interior trim,electrical system ,exhaust , radio,etc , no point in doing half a job 

[j3lly]

When mine did this I changed coolent sensor, no change, new thermostat, cured the problem. But while plenum is off, why not change both.

+ clean all the breathers, change the plugs,check the coil packs,clean the throttle body etc
them pesky plenum things being in the way of all the bits you want to get at 

Might as well do can covers and cam belt while your at it 

Just throw a new engine in....while you're there like. 

and replace the body ,transmission,brakes,interior trim,electrical system ,exhaust , radio,etc , no point in doing half a job 

HaHa that went south real quick

[j3lly]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

[dave the builder]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

feel the rad and pipes going into/out of it
(please be careful not to put hands etc ,in near moving parts like belts or fans)
if they are getting warm before the temp is showing 70 or so, when you start up , probably stuck open stat .
 

[tunnie]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

Fact you mention it's not getting up to operating temp of around 90, and it's stuck around 80 is a clear suggestion is stat, also most common cause and well known for them to get sticky.

Also get the coolant transfer pipe as they are a pig to separate and pipe often breaks. 

[Andy B]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

Start the engine from cold and keep an eye on the temp of the top hose. If it gradually gets warm as the engine gets warm, then the 'stat is stuck open. The top hose should stay cold up to the point of the 'stat opening at which point it should suddenly get hot. 

[Doctor Gollum]

Classic Stat. They usually fail open. 

CTS fails to -40°c causing massive over fuelling... Only starts from cold and then runs like an absolute dog once warm and then won't start. 

[biggriffin]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

for the price of a stat, just replace it.

[j3lly]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

Fact you mention it's not getting up to operating temp of around 90, and it's stuck around 80 is a clear suggestion is stat, also most common cause and well known for them to get sticky.

Also get the coolant transfer pipe as they are a pig to separate and pipe often breaks. 

Coolant transfer pipe are you talking item 15 here

Thanks

[Doctor Gollum]

https://www.omegaowners.com/forum/index.php?topic=144695.0

[j3lly]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

Fact you mention it's not getting up to operating temp of around 90, and it's stuck around 80 is a clear suggestion is stat, also most common cause and well known for them to get sticky.

Also get the coolant transfer pipe as they are a pig to separate and pipe often breaks. 

School boy error

https://vauxhall.7zap.com/en/car/j96/f/0/26-2/

[biggriffin]

How can I prove thermostat is stuck open
Haven't heard my fans come on for a while

Fact you mention it's not getting up to operating temp of around 90, and it's stuck around 80 is a clear suggestion is stat, also most common cause and well known for them to get sticky.

Also get the coolant transfer pipe as they are a pig to separate and pipe often breaks. 

School boy error

https://vauxhall.7zap.com/en/car/j96/f/0/26-2/

Think there's some parts available in the relevant section, from different members, might be worth a look 

[j3lly]

Just done some checks with basic diagnostics ( Torque Pro )
here are the results
Rad top hose out of thermostat starts to get warm at 70'
Whats interesting ( To me anyway )
The 2 smaller dia pipes going to header tank
One gets warm as car warmed up the other only stated to get warm at 70'
A noticeable difference
Rad fans kicked in at 98'

Unsure now
Any thoughts

[Doctor Gollum]

Stat is still stuck open...

That pipe goes from vaguely warm to hot the instant the s stat opens if it's working 

[biggriffin]

Get it changed, why wait for it to jam closed, you are 99% sure it's faulty.