Thermostat faulty?

[ab1702]

Just wondering if it causes any issues running the car with a faulty thermostat that seems to open too early or is stuck open?

My temp gauge has been dodgy for quite a while now. It doesn’t get upto 90 and stay there ever, if it does get upto 90 then it will drop back down at some point sometimes going as low as 70. If I have the heater fans on inside the car then it rarely gets above 70.

I took the car for service and mot last week and asked the guy to change the thermostat aswell. He rang me a bit later saying it’s a nightmare job on my car and he’d want it back another day for most of the day if I want it doing as he reckons he’d have to take most of the front end off to get to it. However in his opinion if the car isn’t overheating then he said he’d just leave it.
Like I said above if I just leave it is there any problems this could lead to as most of the time the car will be running cooler than what it should be?
The car is a 2009 sportback Quattro 170 TDI CBBB engine.

thanks

 

[samisnake]

its 'better' having it stuck open than stuck closed, thats true.
your engine will not be running at optimal temperature, so increased wear and reduced fuel consumption are the main issues.
i wouldnt just leave it.

attached is the elsawin guide on replacing it on a cbbb engine. doesnt look like a nightmare job, take it elsewhere

 

[Matt268uk]

It's not a nightmare job and actually pretty straight forward it your handy with tools. As Sam has shown above, just follow that and you'll be all good.

 

[ab1702]

its 'better' having it stuck open than stuck closed, thats true.
your engine will not be running at optimal temperature, so increased wear and reduced fuel consumption are the main issues.
i wouldnt just leave it.

attached is the elsawin guide on replacing it on a cbbb engine. doesnt look like a nightmare job, take it elsewhere

I appreciate your help and the guide, however that doesn’t look like my thermostat unless I’m looking at it wrong.
On mine I think the thermostat housing has 3 hoses/pipes coming off it and a quick search on eBay for a replacement shows the same thing aswell. The engine is definitely 100% CBBB aswell.

 

[samisnake]

I appreciate your help and the guide, however that doesn’t look like my thermostat unless I’m looking at it wrong.
On mine I think the thermostat housing has 3 hoses/pipes coming off it and a quick search on eBay for a replacement shows the same thing aswell. The engine is definitely 100% CBBB aswell.

just looked again to make sure, and it turns out there is two styles of thermostat on the cbbb.
the one i linked to above, or a different style housed inside a 4/2 way valve like what you saw on ebay.

attached the exploded view and the guide for the 4/2 way valve.
if yours is like the 4/2 way valve one, then you gotta remove the alternator, but a nightmare i still dont think it is tbh.
compare the pics to your car

 

[ab1702]

just looked again to make sure, and it turns out there is two styles of thermostat on the cbbb.
the one i linked to above, or a different style housed inside a 4/2 way valve like what you saw on ebay.

attached the exploded view and the guide for the 4/2 way valve.
if yours is like the 4/2 way valve one, then you gotta remove the alternator, but a nightmare i still dont think it is tbh.
compare the pics to your car

Yes I’ve just found that guide aswell, I’ve just stumbled across what looks like a full free pdf guide of elsawin Online so ive downloaded that.
From what I can see you have to remove the throttle valve module, remove alternator, remove air con compressor, remove the air pipe connected to the intake manifold flap motor and also move the fuel filter out of the way.

 

[stevey83]

Dont suppose youve got the link to the online elswin guides?

 

[Retroman]

Mine runs a bit cold in the winter as well and I have a new thermostat on the "to do" list for 2021. I've had a brief survey of the job and it looks like on the CBBB engine (which I reckon is a great engine) I'll need to move the fuel filter bracketry (leaving the fuel filter pipes connected) and possibly the alternator - I'm hoping just the former

 

[lgooch]

I need mine doing. Looks like a horrible job. Which I was going to attempt myself but after taking a look at it I kinda like the skin on my knuckles so I will be paying someone


Sent from my iPhone using Tapatalk

 

[stevey83]

For anyone interested, ive just done this on a 2009 Tiguan, same engine CBBB. Wasn't to hard a job, a lot needs to be removed to get to the thermostat, i also needed a new small rubber seal for one of the pipes which held me up while VW got one in. I would recommend getting this at the same time you do the job, part number :

06B121687

Number 18 from this diagram:

http://www.oemepc.com/vw/part_singl...121/subcategory/121062/part_id/3691348/lang/e

As for fitting, its just in a tight spot. The alternator neds to come out, which can be done with the AC pump in , its just all a tight space. I took the time to clean up the throttle body and egr valve as well, coked up after 95k miles.

 

[stevey83]

Same diagram for audi:

http://www.oemepc.com/audi/part_sin.../121/subcategory/121035/part_id/258253/lang/e

Although there was a change in thermostat being used depending when your car was made. After 08/2009 its a thermostat in housing with 3 way valve, before 08/2009 it was a thermostat which is replaceable in the block of the engine. Best was is to have a visual inspection of your engine and see what you've got. There not interchangeable either, as the pipe work is different between the revisions

This is the thermostat in block diagram:

http://www.oemepc.com/audi/part_sin.../121/subcategory/121032/part_id/258253/lang/e

 

[ab1702]

Same diagram for audi:

http://www.oemepc.com/audi/part_sin.../121/subcategory/121035/part_id/258253/lang/e

Although there was a change in thermostat being used depending when your car was made. After 08/2009 its a thermostat in housing with 3 way valve, before 08/2009 it was a thermostat which is replaceable in the block of the engine. Best was is to have a visual inspection of your engine and see what you've got. There not interchangeable either, as the pipe work is different between the revisions

This is the thermostat in block diagram:

http://www.oemepc.com/audi/part_sin.../121/subcategory/121032/part_id/258253/lang/e

Mine is a 2009 A3 CBBB engine and it’s the stat in the housing with 3 way valve

 

[stevey83]

This is the thread and repair job i made on the VW Tiguan forums:

https://www.mytiguan.com/index.php?/topic/53524-thermostat-problem-maybe-solved/

The worst thing about the engine not getting to temperature is the fact you'll be using more fuel

 

[3bi5]

Why are you using more fuel if engine is not getting to temp?

 

[samisnake]

Why are you using more fuel if engine is not getting to temp?

Ecu sends more fuel through to get the engine warmed up faster which never happens.

 

[stevey83]

Why are you using more fuel if engine is not getting to temp?

Its only marginal, but you will be using more fuel. Best to get it sorted.