How works a vw thermostat (long read, data heavy)

[obieoberstar]

Thank you for the continued updates. The data is interesting.

It truly is a 'system'.

[oprn]

Thanks for all the good data you provide us!
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[volkaholic1]

it has been awhile since i posted, did some cool weather driving, which i dont normally do. ambient temp 46F, took moms bug out, drive country back roads, 40-55 mph range, about 45 minute drive, 2 stops, left engine running.

i measure engine compartment temp and temp off the 1/2 cylinder side (what the stat sees)

engine compartment temp peaked at 80F -34F hotter than outside, like i said, in a closed bug engine compartment, expect air temps 30-409F hotter than outside

air temp at the stat peaked at 155F = 68C, stat starts to open after a few minutes, but peaked at 7volts 7/12 = 58% open, with a 13mm stroke = 7.5mm so barely half way open, i drove mostly 55, but had to slow down to 40 for awhile, the engine air temp drops to 138F=59C, the stat closes down to 4 volts = 4/12 = 33% = 4.3mm open,

so the stat works exactly like it should, pretty neat i think. i think i know more about VW thermostats than anyone else alive, the experts are all dead by now.
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Volkaholic

[oprn]

[andrig's]

[texastomeh]

FWIW:

I just recently purchased/received a set of flaps and the "original style" Tstat from volkaholic1 (aka Awesome Powder Coat).

The rebuilt flaps look and operate "like new" and of course, the Tstat IS new.

I tested the Tsat with a heat gun (easier and more realistic than dunking in boiling water) and it performed flawlessly. Sorry, but I did not instrument and record actual temps, but I figure they were representative of what the Tsat would see under real conditions.

I then installed the flaps and Tstat on the engine (which is still in mockup) as part of modifying the fan shroud to fit the BT case. Once I got the shroud clearance and cylinder tins tweaked and fitted, I tested the flaps and Tsat with the heat gun again. PERFECT!! - or at least I THINK SO until I finish the build and get it on the road to make sure.

Tstat seems to have plenty of "OOMPH" to operate the flaps, but then the flaps are smooth as budda' and really take very little effort. The secret is to make certain that the flaps and actuating rod are properly installed, aligned, and NOT BINDING!!

It should be noted that IF this type Tsat fails (Heaven forbid ), the flaps will be in the OPEN position. THIS IS NOT THE CASE WITH THE "MEXICAN" STYLE TSAT!!

BTW: APC was sooper to work with re the order.

STAY WELL!!

Tom
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Too bad that the guys that know how to solve all of the WORLD's problems are too busy working on old Volkswagens!!

[volkaholic1]

you are so silly, you know the only part of california they are considering is LA and hollywood, to them, the rest is just fly over
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Volkaholic

[tasb]

Very interesting topic. I found the comments about "California" almost humorous.

California is almost 800 miles from north to south or visa versa. It ranges in altitude from 14,500 feet to nearly 300 BELOW sea level. It's temperatures range from a high of 134 F to a low of -45 degrees F. Kinda negates generalizing about the state of the state
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1961 (October)Single Cab- Road Trip Workhorse

[volkaholic1]

again, i have rebuilt 100's of flap sets, most are fine, but sometimes the bushings are worn out, egg shaped, not sure why, some sort of side load? but they can wear, and if bad enough, even fall out! that would certainly be bad
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Volkaholic

[busdaddy]

[Ulu]

[Ulu]

[volkaholic1]

ok, stats are filled with charge fluid, then put under vacuum, then sealed.
so at higher elevations, with lower atmospheric pressure, it would tend to open sooner, but only slightly, i have a sensor installed on an engine, and during normal driving, that stat runs about 75% open, which makes sense, you still have 25% more to open if the engine gets hotter, a thermal reserve. air temp coming off the heads and cylinders is around 100c
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Volkaholic

[kreemoweet]

[Ulu]

If you drive up 5000 feet, air pressure reduces about 2.5 psi.
That's really not much. Plus the affected area is small.

I'll bet it has almost zero effect.

[sjbartnik]

I would think that altitude would make no difference since the fluid is in a sealed chamber, not exposed to ambient air pressure.

It’s not like boiling water in a pot open to atmosphere.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650

[busdaddy]

Good question, they seem to be under quite a bit of vacuum when cold, whatever the juice is in them boils when they reach temp and they open rather suddenly, it's not a gradual thing like a thermometer rising. I doubt altitude would make a really big difference (but I'm not a scientist).
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[oprn]

Good question, I don't know, at any rate the weather will be cooler up there too...

Thinking about it now, with less atmospheric pressure it should expand, open the flaps and run cooler... a bit. Enough to document? I'm not sure.
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[Ulu]

So when you change altitude, will that move the bellows until the pressures balance?

Imagine a bare thermostat being taken up 8000’.

Does it ever move enough to make a difference?

[busdaddy]