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Model specific boards => Golf mk4 => Topic started by: mcgee9t2 on 10 September 2013, 12:39

Title: Is there anyway to tell whether its the temp sender or thermostat
Post by: mcgee9t2 on 10 September 2013, 12:39
as above, know i need to replace either temp sender or thermostat, is there anyway to determine which it is to save me replacing both...
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: WadGTI on 10 September 2013, 13:02
I replaced my temp sendor as I was having an error in the ECU cooling map. IN the end it was my thermostat.

Symptons - Temp guage running around 75 approx on motorway runs and usually slow driving/standsill, rose to the normal 90. But then would drop to 75 upon normal driving again.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: Rhyso on 10 September 2013, 13:29
You can log the temp via vagcom

Or see if an error code is thrown up in Instruments; module 17
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: mcgee9t2 on 10 September 2013, 18:13
WadGTI - I belive those sympoms happen when either the temp sender or tstat goes...? I have those symptoms but not sure if its tstat or temp sender.

rhyso -no copy of vag com... one of my mates has it but doesent know how to use it... no codes when iv plugged the code reader in...
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: dom on 10 September 2013, 19:18
You can remove the thermostat and test it in a pan of water.

My money would be on the stat being to blame rather than the sensor.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: mcgee9t2 on 10 September 2013, 19:21
any guides on how to log temps on vag com?

im taking it that when you log temps that's the temp seen by the temp sender and therefore if the readings constant its t/stat that's knakerd? (or the other way around)

and dom, how woul I test it in a pan of water? (sorry to sound like an indiot, could proberbly work it out if I took the tstat out and had a look at it but aint got time to do that ATM...)

Cheers
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: dom on 10 September 2013, 19:22
Have a look at this:

http://www.youtube.com/watch?v=aa1yG-fntRk (http://www.youtube.com/watch?v=aa1yG-fntRk)
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: DaveT on 10 September 2013, 20:20
Took my mk4 GTI into VW today with the symptoms described above where the needle sits at approx 75 degrees on long runs. They changed the temp sender as it was showing up as being faulty. This did not cure the problem and so tomorrow is going in for a new thermostat. Hope this helps.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: northeast_gti-t on 10 September 2013, 20:58
Have no Fault codes for mine on vag-com,mine heats up slow ie top hoses/heater hose gets real hot and the lower takes ages to get hot so i'm going for a thermostat also my gauge sits at cold all the time until its been sat at idle for a long time
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: WadGTI on 11 September 2013, 09:13
any guides on how to log temps on vag com?

im taking it that when you log temps that's the temp seen by the temp sender and therefore if the readings constant its t/stat that's knakerd? (or the other way around)

and dom, how woul I test it in a pan of water? (sorry to sound like an indiot, could proberbly work it out if I took the tstat out and had a look at it but aint got time to do that ATM...)

Cheers

Lol. It does sound like thermostat btw. They are cheap as chips. I picked one up from ECP for £6. I would get one and change it and then see where you are with things.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: mar_k on 11 September 2013, 09:34
When my stat went the temp would drop to almost nothing on the motorway,
Completely stuck open it was. I used a circoli stat to replace it and it worked fine ever since
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: Wazzzer on 11 September 2013, 11:15
Sender is dual circuit, one tells the ECU the temp for fuelling purposes the other tells the gauge what to read.

Stat usually makes the car take ages to get to temp and drops during long runs if it's stuck open. If it's stuck shut you'll overheat in no time...
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: dom on 11 September 2013, 12:09
Lol. It does sound like thermostat btw. They are cheap as chips. I picked one up from ECP for £6. I would get one and change it and then see where you are with things.

Do not buy a thermostat from ECP, it will not last long at all. Mine was less than 2 weeks before it failed.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: Bellend on 11 September 2013, 12:30
Lol. It does sound like thermostat btw. They are cheap as chips. I picked one up from ECP for £6. I would get one and change it and then see where you are with things.

Do not buy a thermostat from ECP, it will not last long at all. Mine was less than 2 weeks before it failed.

Buy a quality one from ECP if they do one. The cheaper range admittedly, as much as I rate ECP, are sh!t.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: WadGTI on 11 September 2013, 13:22
Sender is dual circuit, one tells the ECU the temp for fuelling purposes the other tells the gauge what to read.

Stat usually makes the car take ages to get to temp and drops during long runs if it's stuck open. If it's stuck shut you'll overheat in no time...

So in theory, If I am getting the cooling map error code, this should be cause by the temp sender?.

TBH,...I am wondering how the thermostat would cause a cooling map code to show up? as its mechanical rather than electrical? I reliease it would take a long time for the coolant to heat up with a stuck thermostat, however on a good long run, the temp of the coolant will hit and stay 90c?

Or am I just being silly?

Reason for saying this, I changed the temp sendor and still getting the ECO Cooling map code.

THanks
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: WadGTI on 11 September 2013, 13:33
Actually guys, I have just answered my own question. Found this article on the net.

Some intresting reading on the cooling systems for our engines.

http://www.volkspage.net/technik/ssp/ssp/SSP_222.pdf
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: dom on 11 September 2013, 17:39
Sender is dual circuit, one tells the ECU the temp for fuelling purposes the other tells the gauge what to read.

Stat usually makes the car take ages to get to temp and drops during long runs if it's stuck open. If it's stuck shut you'll overheat in no time...

So in theory, If I am getting the cooling map error code, this should be cause by the temp sender?.

TBH,...I am wondering how the thermostat would cause a cooling map code to show up? as its mechanical rather than electrical? I reliease it would take a long time for the coolant to heat up with a stuck thermostat, however on a good long run, the temp of the coolant will hit and stay 90c?

Or am I just being silly?

Reason for saying this, I changed the temp sendor and still getting the ECO Cooling map code.

THanks

When I had a cooling map fault code it was the thermostat at fault.
Title: Re: Is there anyway to tell whether its the temp sender or thermostat
Post by: Scott D on 12 September 2013, 19:56
same fault code as well when thermostat

temps went to 90 when idling but once on the move dropped to 70ish - stat stuck open.