# Running No Thermostat?



## VRpoweredA2 (Oct 8, 2000)

*******UPDATE: The previous owner wired up the relay powering up the 044 Bosch pump backwards!!! It was not getting power at all explaining my lean conditions. BUT...My temps are still going up as stated below******** 

Weather has been getting rather warm(er) around here these past few days and this is when you start noticing cooling problems with cars...
I bought this car about 3 weeks ago. It has 2 Flex a Lite slim fans running off a switch inside the car.
Yesterday it was close to 90 deg. here in NYC and the car was overheating. It wouldnt go past 230 but the high coolant temp + the close to 260 oil temps = no good for my motor/turbo.
I'm going to have to upgrade the fans as they do nothing for cooling in this kind of weather. When i'm driving its fine, but in traffic is when I encounter these problems.
My questions is: Is it safe to pull the thermostat out for a few days before I go replacing the fans to something stronger? I have to drive the car and wont be ordering new fans for another week and a half roughly.

Thanks for the help. 


_Modified by VRpoweredA2 at 3:10 PM 4-29-2009_


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## VRpoweredA2 (Oct 8, 2000)

*Re: Running No Thermostat? (VRpoweredA2)*

I also just ordered a low temp thermostat BUT do not want to install that without upgrading the fans. 
So I think its easier to pull the thermostat rather than install a new one, have the car overheat again = waste of my time.


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## PhReE (Sep 16, 2004)

*Re: Running No Thermostat? (VRpoweredA2)*

I don't really know if pulling the thermostat will help, I mean it's going to be open in these cases anyways. I guess it might flow a bit more without it there, but sure, go ahead and try it.


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## benzivr6 (Feb 16, 2001)

*Re: Running No Thermostat? (VRpoweredA2)*

I have 2 11" spal fans and I ran it off my OEM FCM and it pretty much keeps my car just over the 160 temp. What type of coolant are you using? Do you mix it with mineral water and what's the condition of the radiator?


_Modified by benzivr6 at 5:46 PM 4-27-2009_


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## anti bling (Dec 13, 2003)

*Re: Running No Thermostat? (VRpoweredA2)*

the thermostat if a restrictive element in the cooling system. removing it will cause the coolant to flow to fast to transfer heat to the radiator. this will cause your motor to over heat even more. i would recommend a new thermostat and upgrading the fan set up. removing the thermostat and not replacing it with a new one is a waist of time.


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## PhReE (Sep 16, 2004)

*Re: Running No Thermostat? (anti bling)*


_Quote, originally posted by *anti bling* »_the thermostat if a restrictive element in the cooling system. removing it will cause the coolant to flow to fast to transfer heat to the radiator. this will cause your motor to over heat even more. i would recommend a new thermostat and upgrading the fan set up. removing the thermostat and not replacing it with a new one is a waist of time.

Woah it's not going to cause it to overheat more, it's going to let more flow to the radiator, which would cool it more if anything.


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## 05JettaGLXVR6 (Jan 25, 2006)

*Re: Running No Thermostat? (PhReE)*

As long as its not stuck closed theres no problem. 
Why upgrade the fans? Ive never heard anyone having a problem.


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## Winston_Taco (Sep 13, 2002)

*Re: Running No Thermostat? (05JettaGLXVR6)*

Is your coolant to water ratio too high? Too much coolant will severely lower cooling efficiency. How are your afr's too lean will make it hot too.


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## KubotaPowered (Jan 27, 2005)

*FV-QR*


_Quote, originally posted by *anti bling* »_the thermostat if a restrictive element in the cooling system. removing it will cause the coolant to flow to fast to transfer heat to the radiator. this will cause your motor to over heat even more. i would recommend a new thermostat and upgrading the fan set up. removing the thermostat and not replacing it with a new one is a waist of time.


Bingo! Coolant flows faster around the cylinders, keeping them cooler while the pistons and rings try to get up to OEM temps and they expand at a faster rate than the cylinders do causing premature cylinder and ring wear. I have seen it numerous times here in AZ


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## anti bling (Dec 13, 2003)

*Re: Running No Thermostat? (PhReE)*


_Quote, originally posted by *PhReE* »_
Woah it's not going to cause it to overheat more, it's going to let more flow to the radiator, which would cool it more if anything.

yes it will...... water flowing through the radiator at to high a rate does not give the coolant enough time to transfer heat. thus a overheating problem may be made worse by removing the thermostat.


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## KubotaPowered (Jan 27, 2005)

*FV-QR*

Use water wetter and distilled water, lose the antifreeze


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## 92g60gti (Jul 6, 2004)

*Re: Running No Thermostat? (anti bling)*


_Quote, originally posted by *anti bling* »_
yes it will...... water flowing through the radiator at to high a rate does not give the coolant enough time to transfer heat. thus a overheating problem may be made worse by removing the thermostat.

^ He is 100% correct. The car may take longer to get up to temperature, however once it gets up to temperature it will more than likely just keep on rising especially in traffic. If you were just cruising down the highway then it may be alright because the waterpump is spinning faster and there is a lot more air going by the radiator. Sitting in traffic though or around town the waterpump is not spinning as fast. There is not much air moving through the radiator to cool it down quick enough before the coolant cycles right back out.


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## 92g60gti (Jul 6, 2004)

*Re: Running No Thermostat? (92g60gti)*

I've driven my car car down to waterfest a couples times and h2o the past 2 years with my current setup and i've never had a problem. I've been caught in traffic for a couple hours on a few of those occaisions. I'm running a low temp t-stat and fan switch with a 10'' slim fan. http://****************.com/smile/emthup.gif


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## MKII16v (Oct 23, 1999)

*Re: Running No Thermostat? (92g60gti)*

Have you checked your water pump? You shouldn't have any issues with a properly functioning cooling system....even with the slim fans. A partially stuck T stat sounds likely as well. I would replace the T stat as they are cheap and take a look and make sure you still have a complete impeller on that water pump. The OEM and many aftermarket ones used plastic impellers that didn't hold up with age on some cars. Graff sells a replacement pump with metal impellers.


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## VRpoweredA2 (Oct 8, 2000)

*Re: Running No Thermostat? (MKII16v)*

Hmmmm.....
C2 42 software.
AFR's at idle after warmed up in high 16's low 17's.
When cruising they are anywhere from 14.8 - 15.9.
I feel it is running a bit on the lean side. When boosting i'm seeing 12.6 - 13.2.
As far as coolant goes, It has the orange crap in there. I'm not sure what the ratio is as I bought the car like this.
So you folks recommend not touching the fans?


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## jhayesvw (Oct 3, 2001)

*Re: Running No Thermostat? (VRpoweredA2)*

youre looking lean all the way from idle to full boost if those numbers are right.
perhaps your wideband is off and should be recalibrated
or you have a lean condition which will make your car run hotter.


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## VRpoweredA2 (Oct 8, 2000)

*Re: Running No Thermostat? (jhayesvw)*

It's a AEM UEGO with about 500 miles on it.
I thought it looked a little lean too but had read somewhere that C2's software runs like that around idle/cruise, but I dont care what i've read....I want to be certain.
What do I look for if my car is running too lean? I know I can search but obvious things would be helpful...


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## FaelinGL (Nov 28, 2004)

*Re: Running No Thermostat? (anti bling)*


_Quote, originally posted by *anti bling* »_
yes it will...... water flowing through the radiator at to high a rate does not give the coolant enough time to transfer heat. thus a overheating problem may be made worse by removing the thermostat.

I'm sorry, but I don't think this is right. This is thermodynamically based off temperature and flow. Your rate of heat transfer will increase from the mass flow rate of the coolant. It doesn't matter that it's flowing faster; the bottom line is that the median temperature of the wall will stay lower. Transfer from the cylinder wall to the coolant is convective which is primarily mass-flow rate driven.
Mike


_Modified by FaelinGL at 11:41 PM 4-27-2009_


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## PhReE (Sep 16, 2004)

*Re: Running No Thermostat? (anti bling)*


_Quote, originally posted by *anti bling* »_
yes it will...... water flowing through the radiator at to high a rate does not give the coolant enough time to transfer heat. thus a overheating problem may be made worse by removing the thermostat.


Doubt it, you would have to flow it really damn fast for that to happen. You can remove an ENORMOUS amount of heat with a radiator when the car is moving...


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## KubotaPowered (Jan 27, 2005)

*Re: Running No Thermostat? (FaelinGL)*


_Quote, originally posted by *FaelinGL* »_
bottom line is that the median temperature of the wall will stay lower. Transfer from the cylinder wall to the coolant is convective which is primarily mass-flow rate driven.
Mike

_Modified by FaelinGL at 11:41 PM 4-27-2009_
 
Which is my point, cylinder walls don't expand and the pistons and rings do.


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## 92g60gti (Jul 6, 2004)

*Re: Running No Thermostat? (PhReE)*


_Quote, originally posted by *PhReE* »_

Doubt it, you would have to flow it really damn fast for that to happen. You can remove an ENORMOUS amount of heat with a radiator when the car is moving...

Do some research on it from some sources that know what they are talking about. You are wrong. Like i said before going down the road and around town even he will prooobably get away with it. But if you get stuck in any kind of decent traffic it is most definitely going to overheat.


_Modified by 92g60gti at 10:26 AM 4-28-2009_


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## VRpoweredA2 (Oct 8, 2000)

*Re: Running No Thermostat? (92g60gti)*

Ok.
After speaking with the original builder/owner of the car, hes confident that the fans are sufficient enough. When he had the car, he had A/C in it and even then the fans would cool the car down enough with the A/C on. I'm going to have to agree that there is something else wrong with the car.
I'm going to install the low temp thermostat, change out the coolant to a different one and try and figure out why I have lean conditions which are probably the culprit.


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## MKII16v (Oct 23, 1999)

*Re: Running No Thermostat? (VRpoweredA2)*

I don't think you are going to see an appreciable difference in coolant temps due to it being a bit lean at idle or low load cruise. It certainly won't add any more heat than a properly functioning VR cooling system can handle.


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## Noobercorn (Aug 17, 2007)

*Re: Running No Thermostat? (VRpoweredA2)*


_Quote, originally posted by *VRpoweredA2* »_
I thought it looked a little lean too but had read somewhere that C2's software runs like that.

*absolutely incorrect. *
Jeff shoots for ~ 11.8 at WOT and 14.7 at idle on ALL of his software for safety. i know this for a fact.
sound to me like you need to address this asap. i would start with yer FPR. also, lean conditions could be an indication of a leak in the plumbing. what vacuum readings do you have at idle, WOT, cruise and decel?


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## DieGTi (Jun 19, 2001)

*Re: Running No Thermostat? (Noobercorn)*

I ran a car without a thermostat and water only for a summer when I was in highschool... never over-heated ever. It would get luke warm at idle otherwise it was cold. 
A somewhat lean a:f could also be caused by a high coolant temperature. I would solve the overheat issue before diving into an a:f issue.


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## VRpoweredA2 (Oct 8, 2000)

*Re: Running No Thermostat? (Noobercorn)*

11.8 in boost?! wowsers.
I def have not seen anywhere close to that on this car.

Vacuum @ idle = 18Hng
WOT = It climbs into boost.... ? So I dont have a steady vacuum reading for that.
Crusing = Hmmm...depends on how much throttle i'm giving it but if i'm steady footing-it on the highway at say 60mph...about 15-13? I could be off though. I"ll get a better reading tonight.

Where do I start then? Cooling? AFR? 
Lean conditions causing overheating.
or
Overheating causing lean conditions.









I checked the car over earlier for vacuum leaks and all looks in place. One thing I did notice was the + battery terminal was loose and I tightened it down. I also noticed that the blue recharge plug coming off the alternator and into the main harness was broken. I know voltage plays a roll with the 02 and what not. Disconnected the negative for a while, bolted everything down correctly.
As far as plumbing goes, there really isnt much. I checked and double checked all my piping and couplers. They all appear to be snug without any leaks. There isnt much to the piping anyway:


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## Noobercorn (Aug 17, 2007)

*Re: (pubahs)*

does this interfere with the factory O2? block, it etc.


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## VRpoweredA2 (Oct 8, 2000)

*Re: (Noobercorn)*


_Quote, originally posted by *Noobercorn* »_does this interfere with the factory O2? block, it etc.


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## Noobercorn (Aug 17, 2007)

*Re: (VRpoweredA2)*

any wires touching/interfering/etc? 
how are the O2's mounted, like, in reference to eachother? 
how far apart are they? 
do you have VAG COM to read O2 activity, and compare it to yer wideband?


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