# Dumb coolant question



## rjev (May 29, 2009)

So recently I've noticed that my coolant temp gauge tends to jump around a lot more than it used to. When I was driving the car in the summer, say on a long highway drive, the needle would go about 2/3 to the right, then the fan would kick in and it wouldn't budge from dead centre for hours and hours. 
Now however it'll tend to hover on the notch just past dead centre at highway speed and drop halfway between cold and happy at idle. Buh? 
Fan works, coolant looks good, overflow tank sits at the same level all the time (so obviously nothing is getting in or out), oil is the right colour, no funny smells or weird exhaust, no leaks from anywhere, blahdeblah. New rad a short while ago, new blue CTS. System was flushed (I think) and refilled a few months ago. Two different brands of coolant in there right now but they're the same colour and seem to be getting along fine. Going to flush and fill with G12 this week anyway. 
Oh and I checked the coolant hoses after a half hour drive today and all were hot except the lower rad hose. Normal? I dunno! I'm still learning and this is the first time I've driven in cool weather, so I don't really know what to expect. Am I just being anal and weird or is this isht worth worrying about?
oh OH and I doubt this would have any bearing on stuff but I had to relocate the fan after-run switch when I swapped my boring valve cover for a G60 one. it's just a little further forward and to the left on the head from where it was, but that shouldn't matter, right?










_Modified by rjev at 12:32 PM 10-6-2009_


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## rjev (May 29, 2009)

any idears?


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## camerahunter (Sep 27, 2009)

*Re: (rjev)*

I've only owned my Golf for a couple of weeks BUT on the VW Vanagons the Temp Sender sensor goes bad and things can go wrong. The other thing is the contact on the dash cluster can get dirty and need to be cleaned to make for an accurate read.
That's my ideas but I am big time green to these things.
Thank you,
David


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## rjev (May 29, 2009)

cool, good to know. spent the afternoon giving my cooling system a good thorough flush. unfortunately I had to cut two of the lower hoses and the local VW guy won't have them in until friday.







gives me time to catch up on my reading I guess.
oh and also I bought this purple coolant called VA-012 Plus by some company called Vaico. they're german, comes from germany, german german german. from what I've read it SEEMS to be either G12 or G12+ but I'm not 100% certain. anybody used it?


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## vr2jetta (Dec 16, 2007)

*Re: Dumb coolant question (rjev)*


_Quote, originally posted by *rjev* »_Oh and I checked the coolant hoses after a half hour drive today and all were hot except the lower rad hose. Normal? 

How different was the temp between the lower and upper? This is normally a sign of a bad thermostat. 

_Quote, originally posted by *rjev* »_OH and I doubt this would have any bearing on stuff but I had to relocate the fan after-run switch when I swapped my boring valve cover for a G60 one. it's just a little further forward and to the left on the head from where it was, but that shouldn't matter, right?


Right


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## rjev (May 29, 2009)

upper was too hot to touch for more than a second or two, lower I could wrap my hand around and hold it there as long as I like.


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## vr2jetta (Dec 16, 2007)

*Re: (rjev)*

Change the thermostat, its most likely bad.


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## camerahunter (Sep 27, 2009)

*Re: (vr2jetta)*

I don't know about all the hype about German coolant.
Before I found these forums, starting at the samba to get help fixing one van I never thought anything about it.
My first van ran over 300,000 miles on the same engine, same coolant, same thermostat, never had any problems at all. I never changed the Temp II sensor, never flushed the coolant, and never blew a head gasket. Heck, when and if it ever got a little low I just put in some tap water.
The van is till running fine. All I've ever done to t is normal tune ups and oil changes. All its ever had in it is the normal cheapest green stuff off the shelf at Napa.
Thank you,
David


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## rjev (May 29, 2009)

yep, going to order a new thermostat to go with my hoses tomorrow. http://****************.com/smile/emthup.gif


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## Schrottplatzer (Jun 13, 2009)

I had a similar issue and was concerned, but I've run three different gauge clusters in the past two months while changing nothing else, and each gauge cluster ran a little different. I'm running a low temp fan switch and low temp thermostat and the engine runs dead middle on the temp gauge.


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## crewcheif (Oct 7, 2009)

You can get different temp fan switches. How do we know what temp we have? Color? What’s black?
and I would say it’s the thermostat, without a doubt!


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## rjev (May 29, 2009)

thought about the issue some more and the more I think about it, the less certain I am that anything's wrong at all. on one of the drives the fan actually came on and I saw the gauge fall to almost dead centre. I don't think it was coming on those other times because the car just wasn't fully up to operating temp. so I just flushed and refilled the coolant without replacing the thermostat this time because honestly, I don't think it's faulty. I'll take it for a few loooong drives this week, see how it behaves. if it seems funny I'll drain the coolant again (but this time I'll save it--expensive haha) and THEN replace the thermostat. just wasn't convenient to do it this time around. but hopefully I won't have to replace it at all. 
**edit: haha yeah so I was way wrong. definitely a non-opening thermostat. the lower half of the rad is cool enough to touch, as well as the lower rad hose. however when the rad fan kicks in the coolant temp drops to dead centre within about 10 seconds, so I'm not worried about overheating--the gauge gets a little past 2/3 and that's it, fan time. I'll definitely replace the thermostat at some point, just not right away. maybe next week when I've got a day to kill. thanks again for the good advice folks. definitely some lessons learned in this thread. http://****************.com/smile/emthup.gif


_Modified by rjev at 1:32 AM 10-11-2009_


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## rjev (May 29, 2009)

oh and one other thing that I've been curious about: what's the coolant temp range on the mk2 8v engine? like, what's the temp at 1/4, 1/2, 3/4, etc. and generally how hot is too hot with these engines?


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## rjev (May 29, 2009)

*Re: (rjev)*

so I woke up this morning feeling uneasy, just not happy that my 'stat wasn't working correctly. so I replaced it! totally wasn't as bad as I thought it'd be and I managed to save about 80% of the coolant. today was a good day.


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## rjev (May 29, 2009)

ok now I'm having the opposite problem, though I don't know how much of a problem it really is. whereas before the temp gauge was tending to get way high, now it tends to stay below the middle. if I sit for a while at idle it'll creep just past the middle but no further. I made sure to install the 87C thermostat and tested it beforehand. it's definitely working as it should. coolant temp sensor is new and the heater blows hot hot air within a few minutes of startup, so I know the thermostat isn't stuck open. it gets up to temperature as quickly as it should, it's just a lower temperature than before.
at highway speeds it's within a certain range below 1/2. it doesn't get any colder or hotter (unless I idle it, then it heats up a bit more). I made MSpaints!
at its warmest:








and at its coolest:








so my question: is this too cold? would a higher concentration of antifreeze in the coolant bring up the temps a little? I'm probably around 50/50 right now. I REALLY don't wanna change the t-stat AGAIN.










_Modified by rjev at 9:24 PM 10-20-2009_


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## 4ePikanini (Aug 29, 2007)

*FV-QR*

change the t-stat to an original oem.
change the temp sensor on the flange that bolts onto the head

I live in conditions where temps get up to 33 celsius. My temp sits in the exact middle under all conditions ( towing, idle, town, highway )
flush the system good and fill with 50% antifreeze and 50% distilled water - DON'T use tap water.


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## rjev (May 29, 2009)

done done and done--G12+ coolant, distilled water, new OEM 87C(standard) tstat and O-ring, new CTS. flushed system thoroughly--head, rad, heater core, all hoses, etc. coolant is perfect, the exact same colour as it was when I mixed it--level stays constant, no cloudiness, no bubbling. the only issue is the temp--it's consistent, just kinda low.


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## 4ePikanini (Aug 29, 2007)

*FV-QR*


_Quote, originally posted by *rjev* »_done done and done--G12+ coolant, distilled water, new OEM 87C(standard) tstat and O-ring, new CTS. flushed system thoroughly--head, rad, heater core, all hoses, etc. coolant is perfect, the exact same colour as it was when I mixed it--level stays constant, no cloudiness, no bubbling. the only issue is the temp--*it's consistent, just kinda low.
*


then don't stress about it.


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## vdubgti2.0 (Apr 4, 2005)

*FV-QR*

You may want to check the cap, if the t stat is not opening which would cause a cold hose on the lower end the issue may be that the cooling system is not pressurizing itself. This would cause the t stat not to open which may be the issue you are having, normally this would cause the car to run hot not cold. Just a thought


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## rjev (May 29, 2009)

*Re: FV-QR (fourie_marius)*


_Quote, originally posted by *fourie_marius* »_
then don't stress about it.


yeah the more I think about it the less I am. everything is obviously working optimally, temp is being regulated properly etc. it's just being regulated at a slightly lower temperature. as long as this won't cause any sort of engine damage over the long term then I won't worry about it.


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