205 Gti 6 Heating Issues 'confused'

[Roon 29 1 Cars]

Hello people.

 

Recently bought my gti6 205, having already replaced alternator ,tensioner etc ive developed a worrying issue that took a nasty turn today.

 

Basically my temperature gauge sits 'driving' on the 3rd mark or just underneath which is a lot lower than where my old 1.6 did. Now when i sit in traffic or say slow driving in residential it either creeps up or sometimes worryingly fly s up! Ive investigated under the bonnet and the coolant isnt hot enough to warrant the mark on the gauge so i thought ok dodgy sensor or something. But a few times its gone right up just before ive parked up and it leaks a fair amount of water from the overflow.

 

Bare with me its a odd issue,

 

Now yesterday the temp gauge went all the way up this whilst driving between 40-60 mph softly at 8am so very cold. And at the same time cold air was coming into the car even tho it was set on hot. 5 minutes later it came racing down to under the 3rd mark and hot air resumed from the vents as weak as it is. Then was fine all the way to work where i enter slower residential areas. At no point has the red light come on and stop sign!

 

Now this morning it behaved itself exact same drive, drove the same way etc and temp stayed around 3rd mark. Checked fluids at lunch and my Expansion tank was BONE dry. Scared me just a little. Luckily no damage has been done. Has never done this before!

 

Also when i start the car from cold the gauge sits at the first mark btw. Cant remember if that is normal.

 

Really need some help love the car but scared to drive it.

 

Thanks paul

 

Edit also it has the dual fans from a 306 but these are not cutting in ever not once. Not even the first one.

Edited February 27, 2013 by Roon

[j_turnell 137 3 Cars]

Might be a good idea to post a picture as to how its plumbed up.

[Roon 29 1 Cars]

I'll get one up tomorrow as its dark now, but good idea. Its very messy under there not up-to my scratch, i say messy, its just obsolete wiring that needs to be taken out and neatened up.

 

I know the temp sensor is the green one with 2 pin.

[Richie-Van-GTi 71 2 Cars]

Hate to say it but get a sniffer test done as soon as possible. It sounds very much like a small blow on the head gasket. Try bleeding it all through properly to be sure all air locks are removed then run it up to temp. Do the hoses pressurise? If you run it with no expansion cap does the level rise sharply? The guage rapidly changing and heaters changing suggests to me the head is filling with air so the thermostat isn't operating correctly, it requires a lot more heat in the air to open it then the hot coolant will rush around and hit the heater matrix etc.

Edited February 27, 2013 by Richie-Van-GTi

[Roon 29 1 Cars]

Something i did not want to hear had been my thought. However its all just been put back together around 1500 miles ago. Engine is very clean and cant see any signs of sipping etc, The hoses are fine coming in and out of the engine/rad but ill try and running it up with no cap on for air leaks. When i refilled it today i pumped the hoses through to get out any air but i was tight on time at lunch.

 

Im running the standard 1.6 expansion tank and cap..... and ive read that they are not high enough rated for the 306 gti engine? I was using my friends Triumph TR6 rated to 13 psi and it was running perfect until i gave it back 2 days ago and this all got worse. Hmm.

 

Trouble is i have no faith in the previous owner hes a qualified mechanic but full of s*it. Front pads don't exist, CV boot was totally hanging off indicators not working, things hard pushed to pick out in winter dusk. He said he never had a issue with it. Thinking when he put it all back together hes done something wrong.

[welshpug 1,657]

I know the temp sensor is the green one with 2 pin.

 

 

thats the one for the ecu, your gauges run off the blue one.

[Roon 29 1 Cars]

So ignore the Green plug as that wont be related to my issue? Is the Blue one the coolant sensor switch for the Dash?

[Richie-Van-GTi 71 2 Cars]

The temp sensor wont have any bearing on heaters in the car, radiator fans or coolant loss.

[Anthony 1,003]

As above, I would suspect that this is more than an electrical issue.

 

Very low coolant level would certainly explain the lack of heat from the heaters and potentially the severe temperature fluctuations, but I would be questioning where the coolant has gone. There really should be no coolant loss, or certainly no more than a small top up once in a blue moon.

 

A poor expansion tank cap certainly won't help. A good 13psi standard cap is just about OK, although I would say that ideally you want a 20psi one.

[Roon 29 1 Cars]

The cold air inside the car only happened that once tho which is odd, behaved itself today, gave it some death here and there and still ok. No coolant lose whatsoever and gauge stayed correct.

 

Received my Brand new 13 psi expansion tank cap so that may improve also as while my friends one was on it was great.

 

I'm at my friends garage on saturday doing brake pads and various other things, what tests ideas should i try, ill do a sniff test, pressure test fluid flush etc. Anything else

 

Also on further looking and researching the blue and brown sensors are not there they have been replaced with literally 'spade' connectors? WTF? It has the BM baker adapter on it btw.

 

I have money from today to throw at it so suggest away. Also how do i upload pics?

[welshpug 1,657]

Also on further looking and researching the blue and brown sensors

are not there they have been replaced with literally 'spade' connectors?

WTF? It has the BM baker adapter on it btw.

 

 

 

that'll be the two original 205 temperature senders which have a calibration closer to what the instrument cluster requires than the gti6's items, the brown sender is not used anyway as that is for the aircon equipped cars and their fan control units.

[Roon 29 1 Cars]

Ok thanks, so in theory the ones i have give me a more accurate reading yes? And i should keep them.

 

Need to wire in a fan control switch as ran it up high at lunch and neither cut in and cant be bothered to sit there searching.

 

My general idea was to give it to Miles next month to go over it? Just GTI's is just down the road but not heard great things.

 

Appreciate all the help so far guys

[Slo 283 1 Cars]

I'd take out the thermostat for a couple of days and see if it still shoots up and down. My turbo lump used to overheat really fast at one point, the guage would rise steadily all the way to the end, fans running and cold heater, my thermostat was fried so much from all the overheating it had stuck shut.

[welshpug 1,657]

Just gti's have gone.

 

I service for a guy that runs a Saxo rally car 1/4 mile from where they used to be as it happens

 

 

dropping it off with miles is a good plan, I would urge you not to use it till then as you don't want to cook the thing.

Edited February 28, 2013 by welshpug

[Anthony 1,003]

Just fix the standard fan system rather than lashing in a switch - it's very simple, and probably just a bad connection or a dead thermoswitch.

 

To be honest, it sounds like the whole cooling system needs a good going over to see what's amiss - it's all cheap and straight forward to address.

[Roon 29 1 Cars]

Just GTI's horsham? Rang them up not 3 months ago for some bits on my 1.6 and they were there although not very helpful.

 

Have to use it have no option to get to work or about as my second car i cant get on the road till 7 weeks time Sucks

 

Miles is a top guy so knowledgeable but that's a good 50 mile run at least. But i will give it to him and say look heres 500 quid make it how you would have done.

 

Ill be taking thermostat out and changing that too buddy. Yeah money isnt the problem seems all reasonable its just my lack of time and knowledge on the pugs.

 

Been in mad fiesta's for too long lol.

[Richie-Van-GTi 71 2 Cars]

If you must run it around for the time being I would go with the above suggestion of thermostat removal. Just pop it out, cut the middle out of it and put it back in. This will prevent any air locks in the head and help it run cooler for longer preventing any damage. Once given to miles I'm sure he will pop a new thermostat in anyway as a matter of procedure and they only cost peanuts.

[Roon 29 1 Cars]

Well had a play saturday. Put a new expansion tank cap on flushed it through filled it back up with decent antifreeze and its been spot on.

 

Also took the front end off and saw why my dual fans didn't cut in. Turns out a certain blue wire wasn't connected. Some mechanic that previous owner was FFS!