Is This Normal For a a Holley TStat?

[campbdon]

One of the latest projects is inspecting and understanding my cooling system. I just did a vinegar soak (2days) and plan to repeat. After the 1st flush, while at the dock in gear (1200RPM) the temp rose to just over 200F, then I clamped the bypass hose. After about 1 min the temp fell sharply to 150F. Seems like a good flow of water at the exhaust (some white smoke). I decided to check condition of Tstat so removed it from the rusty soup, took it apart and cleaned it up with vinegar and CLR. While testing it in pot of water the "mushroom" piece only opens about 1mm around 180F. Does that seem right in terms of allowing sufficient water diversion? Photo attached. I want to reassemble everything but wonder if the Tstat is working properly and whether I should simply remove it as so many of you seem to have chosen to do. I intend to install a ball valve in the bypass hose as I'm convinced on it's benefits for running cooler.
Thank You in advance
DonC

[Al Schober]

Sounds like that thermostat isn't working. Recommend removing (or replacing). Overheating an engine will often kill the thermostat. Try it without a thermostat, you may just like it. I did about 20 years with no thermostat.

[campbdon]

That's where I'm at now Al. I removed the stat and ran the engine in gear at the dock @1200. This time couldn't get temp over about 110-120F !!! Even with bypass valve open. The lake water's not too hot or cold. t's currently sitting in vinegar for a few days then I'll retest. What's the downside of a cool running engine?
Thanks
DonC

[ndutton]

What's the downside of a cool running engine?

Fuel consumption, power and harmful contaminants in the oil to name a few.

[Al Schober]

Neil may be right - don't know.
If fuel consumption increased, I didn't notice it.
Power? I still had enough.
Oil contaminants? Changed oil annually.
I considered running my engine hotter when I was thinking of installing a water heater. Never got there.
Oh yeah, soaking in vinegar isn't going to restore it to life. If it was overheated, it probably lost some of the wax in the module. Wax expands when it melts - that's how a thermostat works. Overheat, overexpansion, failure of the capsule.

[campbdon]

Thank you Al and Neil. Wax really? Thought it was due to thermal expansion of the metal slug inside. Anyway I shall retest some more and report back.
DonC

[ndutton]

Wax really? Thought it was due to thermal expansion of the metal slug inside.

The key component inside a thermostat is a wax motor. More info here.

Oil contaminants? Changed oil annually.

Oh yeah, serious oil contaminants and the reason short start ups in the slip are detrimental for your engine in the long term. Here is the last paragraph from this source:(while reading the last sentence think 'engine not allowed to reach full or preferred operating temperature')

ACID NEUTRALIZERS
As the engine operates, acidic by-products from the combustion process get past the piston rings and into the oil. The acids combine with moisture (every gallon of gasoline burnt produces 1/2 gallon of moisture) which can dissolve bearing surfaces.

Modern motor oils contain additives to combat the acid build up in the oil. As the oil becomes contaminated and turns acidic, the additives get used up. Preventing acid buildup is a very big reason for changing motor oil regularly. Short trip driving is the worst kind of driving for this problem as moisture is not boiled off during driving cycles.