hotter thermostat?

Since it's gotten cooler, my car has been running cooller. In the summer it would hover around 190, but since it's gotten colder I'm running 160-175. Perhaps the thermostat is stuck open. Has anyone tried a hotter thermostat and would the car run better with one? I've heard gasers getting improved mileage/performance by swapping to a hotter thermostat.
Keith

It helps to block your grill off with something like cardboard or the nice kit from worldimpex. That's the only way I can get mine to warm up unless it's above 35degrees.

keith102 said:

Since it's gotten cooler, my car has been running cooller. In the summer it would hover around 190, but since it's gotten colder I'm running 160-175. Perhaps the thermostat is stuck open. Has anyone tried a hotter thermostat and would the car run better with one? I've heard gasers getting improved mileage/performance by swapping to a hotter thermostat.
Keith

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I have often wondered the same thing, but have not tried it. Just out of curiousity, how do you know it hovers around 190 in summer? and recently, 160-175? do you use a scangauge/VCDS, or are you just estimating?

Our TDIs don't waste much heat. The simple fact is they have a hard time saying warm and it is not a thermostat problem. A hotter thermostats would only make it hotter in summer as you thermostats may already be closed. The thermostats only controls the upper end. Putting in a hotter thermostats would not make it warmer in winter, assuming your current thermostats is working properly.

Many people have partly blocked the radiator intake area so there is less air cooling the engine. ( I just noticed you are in GA, not likely needed there.)

As I recall the numbers, your winter readings are what your summer readings should be. It seems you may be running a little warm in the summer. I run about 173 all year long.

BTW how are you measuring the temperature? Does you car have a true temperature read out? Are you using a SCANGAUGE? Many OEM thermostats show numbers, but in reality they are nothing more than a dummy light and only show two temperatures, one for normal and one for hot, some may include a cold setting as well.

You don't need to block your grill in GA (Georgia). It just isn't cold enough here for that. I would have the car scanned to see what the temp really is. Where in GA are you located?

In the summer it would hover around 190, but since it's gotten colder I'm running 160-175.

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Is this the gauge on the dash or vagcom/scangauage reading? The dash gauge is horribly inacurate.

I was able to source an aftermarket 203F t-stat through national auto. Seems to bump the mpgs up slightly (1-2mpg).

using the factory dummy gauge. I know it's far from accurate, but I expect it to be consistent. 190 in summer, 160-170 in winter. no problem getting cabin heat, just that the car isn't running at 190. I live in Canton, 20 mins N of Marietta.

Keith, I think you should check the lower hose to see if the thermostat is opening at all. I don't have the temp spec it on hand, but if you don't reach the temp for it to start opening as it is, getting one that doesn't open till later is not going to help...

Let me see if I can find the spec for the thermostat....

According to my Bentley, A4 thermostats don't start opening until 185F and won't fully open until 221F.

I'd suspect you either have on stuck open (not likely) or just don't drive long and hard enough to get it open. If you drive the car for a few minutes and then stop, open the hood and feel both radiator hoses. The thermostat is on the lower hose, near the front (belt end) of the engine. If the thermostat has opened, that hose should be warm.

Fred

greenskeeper said:

Is this the gauge on the dash or vagcom/scangauage reading? The dash gauge is horribly inacurate.

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I agree.



113c is equal to 236F

I'll get with a buddy who has Vac Com and see what it's showing.
I drove for 40 miles around 60mpg with about a dozen stops yesterday, even turned the heater off for 20 mins to see if it was pulling all the heat from the engine, same results. My normal track to work is the same, 40 miles about 40 stops, 85 min drive and the temp gauge never comes close to 190. This wasn't a 5 min drive.

I recently had a fella who called after a rebuild. He said that his engine seemed to be running hot.

You don't have to have a scan gauge. I told him to put a thermometer in the overflow tank. A kitchen thermometer, like a candy thermometer, works fine.

It could be that your water temp sensor is bad. The way that car's 'idiot gauge' reads is 190, no matter if the engine is at 165 or 220. I never saw one read 170 for any reason, even if the engine was 170 degrees.

greenskeeper said:

Is this the gauge on the dash or vagcom/scangauage reading? The dash gauge is horribly inacurate.

I was able to source an aftermarket 203F t-stat through national auto. Seems to bump the mpgs up slightly (1-2mpg).

Click to expand...

More information on the source of this 203F Thermostat please?
Brand?
Part Number?

I've not heard of National Auto?

Yes, the dash gauge is very inaccurate. Mine reads 190 while the Scangauge reads 165 on the low end and was still at 190 when the scangauge read 227.

A new temp sensor is pretty cheap, quick and easy to change and is known for going bad. The VagCom or scangauge check is easier yet - Remember that there are 2 sensor elements in the temp sensor unit - one that the ECU/VagCom looks at and one for the dash - the one that VagCom reports is the important one, the other is just what you see on the dash. I like Frank's idea also if you have a thermometer that fits in the reservoir

greenskeeper said:

Is this the gauge on the dash or vagcom/scangauage reading? The dash gauge is horribly inacurate.

Click to expand...

Well, it's not really intended to be accurate, just a ballpark idiot gauge. Idiot lights have gone out of style.

Then consider that so many people ignore lights and gauges....who many posts have come up here stating something like "Steam and a funny smell started coming from under the hood and the thermometer light started blinking. I kept driving and now the car is dead...."

A new temp sensor is pretty cheap, quick and easy to change and is known for going bad. The VagCom or scangauge check is easier yet - Remember that there are 2 sensor elements in the temp sensor unit - one that the ECU/VagCom looks at and one for the dash - the one that VagCom reports is the important one, the other is just what you see on the dash. I like Frank's idea also if you have a thermometer that fits in the reservoir[/quote]

If you go into the cluster you can also read the other sensor and compare it the engine side of the sensor. Most of the time I find them wthin 2-3 degrees of each other.Joe