running temperature problem

[michaelcrxvt]

hi, i have a 2009 audi a4 2.0 tdi quattro 170bhp caha engine and it very rarely gets up to temperature.
the needle usually gets upto about 80 mark and keeps dropping down slightly, very rarely will it get to 90 and if it does it drops back down shortly after.
i plugged vcds in today after a 20 mile journey, vcds showed 70 degrees, i left the car to idle for around 20 minutes and the temp slowly got upto vcds 92 degrees, the needle was also showing 90 degrees, the fan never kicked in, i drove the car and the temp dropped down to vcds 69 degrees after a few minutes the temp needle also dropped down.
points to meantion -
the car is only getting 29mpg according to the dis.
the fan never kicks in
when the needle eventually showed 90 the reading on vcds was 80 degrees.
can anyone help ?

 

[blueleggy]

Sounds to me like the thermostat is stuck open.

Graham

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[youngsyp]

I'd agree.

The poor fuel economy is a result of the ecu not coming out of 'cold start', because it the coolant doesn't get warm enough.

The coolant temp gauge in the car is an indicator only. It shows roughly the correct coolant temp so your VCDS reading of 80 degrees when the gauge was showing 90 degrees wouldn't be unusual.

Paul

 

[michaelcrxvt]

does anyone know where the thermostat is on the caha engine ?

 

[Meemo]

 

[Marky007]

Could be air block in coolent system ?

 

[blueleggy]

I would expect an air lock to cause over heating rather than preventing the engine getting up to temperature.

Graham

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[jakm15]

My 2.0tdi CAGA A4 Avant only gets to 90 when your booting it or it’s regenerating.

I’ve had it 2 years now and done about 10k miles and had no problems, does about 40mph on short runs and 50mph taking your time.

I’ve always wondered if my thermostat is nakered but thought that my cars running fine so I’ll leave it. It doesn’t seem like there’s an easy and definite way to find out though, without replacing it.


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[Marky007]

I would expect an air lock to cause over heating rather than preventing the engine getting up to temperature.

Graham

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Yeah I agree but happen to my bmw 530d and this was issue.

Every time you booted it temp dropped

 

[Marky007]

Mine sits at 90 once up to temp and dont move cjca 143bhp engine.
I did do a full coolent change when I got it.