TTinCT

My car recently had the timing belt replaced and we installed the Behr thermostat that comes with the DG kit. (please note i am not flaming or questioning any reseller about the authenticity of these parts)It replaced my dealer purchased OEM t-stat.

What i am going to try and do is potentially answer the question on which t-stat runs cooler. Keep in mind both work!

All temps are monitored via Scangauge and the OBD port.

Observations:
After driving the car for a couple of weeks, and it has plenty of time to settle (no bubbles and plenty of coolant), i immediately noticed that the car at idle would run at around 198 deg F. Prior to the Behr being installed, the car would run between 193 and 195 deg F.
At speed is where the difference seems to be more pronounced. The Behr t-stat runs between 197 and 205 while the OEM t-stat runs between 188 and 197. The initial conclusion i had was that the Behr t-stat does not flow as much coolant as OEM, but without a way of testing this officially, it is just an opinion

The Test:
In trying to replicate Rich's (SparTTan's) test with the OEM t-stat with the Wahler t-stat, I approached this effort the same way...

First initial impressions...visually, they are almost identical. There were some discrepencies in the labeling...
Behr = Made in Germany, marked BTO/BTT
OEM-dealer= Made in Germany, Audi part number, flagged for Audi/VW, BTT marking...

Note the Behr is on the left...
<img src="http://images44.fotki.com/v1410/photos/7/89907/7184960/IMG_2811-vi.jpg">
<img src="http://images21.fotki.com/v632/photos/7/89907/7184960/IMG_2812-vi.jpg">

I put both t-stats in a sauce pan with water and began the heating process...note Behr is still on left..
<img src="http://images29.fotki.com/v1133/photos/7/89907/7184960/IMG_2814-vi.jpg">

From a distance, there looks to be a MINOR difference in the springs...but i did not measure them
<img src="http://images28.fotki.com/v1001/photos/7/89907/7184960/IMG_2815-vi.jpg">

Side by side, once heated...it appears that the dealer t-stat is open a bit more than the Behr t-stat on the left

<img src="http://images24.fotki.com/v854/photos/7/89907/7184960/IMG_2823-vi.jpg">

From this angle, look at the post at the top of thermostat (where it meets the housing)..it could be the angle, but to me there seems to be more post exposed on the t-stat on the right, which is OEM-dealer.

<img src="http://images26.fotki.com/v938/photos/7/89907/7184960/IMG_2825-vi.jpg">

As the water cooled, notice how the Behr on the left seems to close a bit quicker...and notice the spring difference as well..
<img src="http://images46.fotki.com/v1453/photos/7/89907/7184960/IMG_2826-vi.jpg">

good angle...but the difference is very subtle...
<img src="http://images21.fotki.com/v842/photos/7/89907/7184960/IMG_2827-vi.jpg">

Cooled down...notice the difference again..

<img src="http://images42.fotki.com/v1364/photos/7/89907/7184960/IMG_2829-vi.jpg">

<img src="http://images47.fotki.com/v1399/photos/7/89907/7184960/IMG_2830-vi.jpg">

In the end, your conclusion may be different then mine...but it sure looks to me that the Behr is a bit slower to open, close and when fully open seems a bit shy of OEM...question is, is it enough for a 10 deg F difference when at speed....

You be the judge...

oc_tt

Heck you never know, the OEM could be made by Behr as well.

TTinCT

very well could be, although there are no markings on it to indicate it is..

roadyTT

How did you mount the Scangauge...and wheres the thermal data?

TTinCT

same place it has been since i bought the gauge..

<img src="http://images31.fotki.com/v1099/photos/7/7305/6010891/IMG_0627-vi.jpg">

Hard data would need to be retrieved via VAG and i have not done that yet...

MCPaudiTT - DEFCON 1

two OEM supplied ones that have this degree of variance between them. Or not.

roadyTT

I just wanted a thermometer in the pan is all

TTinCT

but seeing as they are in the same pan of water at the same time, the conditions are identical regardless of temp...

Besides, all i had was a meat thermometer that went to 190 deg! ;-P

<img src="http://images20.fotki.com/v208/photos/7/89907/7184960/IMG_2818-vi.jpg">

oc_tt

Not uncommon in the auto parts world. Behr is one of the leading OE providers.

roadyTT

Well done