Definitely thermostat?

miniyazz

miniyazz

miniyazz

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I'm pretty sure but curious to know if anyone has any other thoughts.

Lately I've noticed the car taking a little longer to get up to temperature than normal but put it down to cold weather (city driving). However went on a longer run over the weekend and noticed the temperature gauge being at temperature but then dropping off so plugged in my OBD reader and temperatures dropped to as low as 56°C on the dual carriageway/A roads.

Coolant levels fine and warm air still coming into the cabin. At low speeds/in traffic it still gets up to temp. I was pretty sure it's the thermostat so blocked off a section of radiator with bin liner for the journey back and temps were about 15°C higher so significantly better if not quite right..

Thoughts?

Car in sig, MkIV Golf 2.8L
 
What car is it?

My A3 does the same every winter, I've changed the thermostat and the temp sensor and it still does it so I've just decided to live with it.
 
It generally depends on the type of temperature readout you have in the car but I believe that era VAG should always sit bang on 90 - it was certainly the cause with my A3 1.8t anyway, changed and it sat in the middle thereafter.
 
Minstadave said:
What car is it?

My A3 does the same every winter, I've changed the thermostat and the temp sensor and it still does it so I've just decided to live with it.
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This^^ you can also use the climate control panel to display a coolant temp reading as well. Should sit around the 90 degree mark. Could also be the impellor of the water pump breaking off, they are plastic on vw. ECP/GSf do one with a metal impellor.

Go for stat and sensor first

Alex
 
Minstadave said:
What car is it?

My A3 does the same every winter, I've changed the thermostat and the temp sensor and it still does it so I've just decided to live with it.
Click to expand...

See my ninja edit :p
That can't be right, did you test your thermostat when you took it out to be sure? (or before putting in the new one)

rodenal said:
It generally depends on the type of temperature readout you have in the car but I believe that era VAG should always sit bang on 90 - it was certainly the cause with my A3 1.8t anyway, changed and it sat in the middle thereafter.
Click to expand...

Yeah it always used to (on the calibrated gauge - normal operating temperature is 85-105°C).

telewebby said:
This^^ you can also use the climate control panel to display a coolant temp reading as well. Should sit around the 90 degree mark. Could also be the impellor of the water pump breaking off, they are plastic on vw. ECP/GSf do one with a metal impellor.

Go for stat and sensor first

Alex
Click to expand...

Oh can I? That'd be handy, any idea how I make it show it?
I don't think it's the water pump otherwise I'd surely get overheating rather than underheating? (There is an auxiliary water pump).

Gonna get it changed on Friday. Unfortunately too busy and cold weather/early nights over the next couple of weeks at least to do it myself :( so into the garage it goes..
 
Seeing as it's a MK4 Golf, yep - uber common. My 1.8t I used to own had the same issue. New thermostat and it warmed up quickly and held temp fine.

Have to post back once done to let us know if it's fixed it :)
 
Clarkey said:
Yep, if temp goes down while driving and comes up again when stationary it's definitely the stat.
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Or the car is just overcooled. My A4 does this (only very slight drop in temp when moving, on very cold days like today), and the thermostat is absolutely fine.

Pain in the backside though as it means during the cold days the car doesn't reach temperature very quickly at all!
 
Stormster said:
Seeing as it's a MK4 Golf, yep - uber common. My 1.8t I used to own had the same issue. New thermostat and it warmed up quickly and held temp fine.

Have to post back once done to let us know if it's fixed it :)
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His is a 2.8... id love to see the pics showing whats involved in getting the stat off that :D
 
Matt82 said:
His is a 2.8... id love to see the pics showing whats involved in getting the stat off that :D
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I think access is the main problem, as with so many jobs in this engine bay! I've had to play around with the coolant sensor a few times which is quite closely positioned to the thermostat and realistically requires loosening (at least) of the bumper/radiator to get reasonable access to it.

paradigm said:
Or the car is just overcooled. My A4 does this (only very slight drop in temp when moving, on very cold days like today), and the thermostat is absolutely fine.

Pain in the backside though as it means during the cold days the car doesn't reach temperature very quickly at all!
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How much does yours drop by?
 
I've seen it drop maybe 1/8th of the guage, typically when I'm barely labouring the engine, say doing 50 on an open, straight, flat piece of road.
 
Mine is running cooler now the cold weather is starting to set in, I can get pretty much all the way to work before it's up to full temp which is just under a 15 mile trip.
 
paradigm said:
I've seen it drop maybe 1/8th of the guage, typically when I'm barely labouring the engine, say doing 50 on an open, straight, flat piece of road.
Click to expand...

Have you ever seen what it goes down to on obd?

In my experience the water temp will only ever go down to the temperature stamped on the stat (86* ish in my case)

If yours is going down lower than the temp of the stat then i expect it is broken
 
paradigm said:
It's been checked (and replaced) twice, Audi are adamant that it's fine.
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The gauge is "buffered" as we, so rarely reads accurately.

they usually show full temp by about 60*, so if yours is going left of centre, it could be pretty cold

its hardly the end of the world though, but your heater wont be as warm
 
If the stat is ok then it's a poorly engineered that shouldn't happen. Many new eco type cars have automatic rad blocking systems, if not that would be an option.
 
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