Does anyone actually make a good thermostat anymore?

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The MG is acting like the thermostat has gone back-it takes forever to warm up and then rests halfway between "C" and "N" on the temperature gauge(with a drop at high speed constant load with the weather cold now). It normally jumps right up to a tiny bit past the "N" mark within a couple minutes and stays parked there unless I'm doing something like stop-and-go in hot weather. The heat is not blowing very warm, so I'm confident that this is real and not an instrument error.

This thermostat is not very old. I run a 195º Tstat in there, and when I had the engine rebuilt the shop installed a 165º TStat(ditching the 195 Stant brand that had been in there a few years and had been great). I changed it for a 195 that I think was Intermotor branded back in February or so, and now as I said I'm almost positive it's stuck open.

The Tstat is the same as used in a small block Chevy, so quite literally any parts house in the country will have one in stock.

Should I hunt down another Stant, or is it just luck of the draw with any of them now?
 
The MG is acting like the thermostat has gone back-it takes forever to warm up and then rests halfway between "C" and "N" on the temperature gauge(with a drop at high speed constant load with the weather cold now). It normally jumps right up to a tiny bit past the "N" mark within a couple minutes and stays parked there unless I'm doing something like stop-and-go in hot weather. The heat is not blowing very warm, so I'm confident that this is real and not an instrument error.

This thermostat is not very old. I run a 195º Tstat in there, and when I had the engine rebuilt the shop installed a 165º TStat(ditching the 195 Stant brand that had been in there a few years and had been great). I changed it for a 195 that I think was Intermotor branded back in February or so, and now as I said I'm almost positive it's stuck open.

The Tstat is the same as used in a small block Chevy, so quite literally any parts house in the country will have one in stock.

Should I hunt down another Stant, or is it just luck of the draw with any of them now?
Wahler is OE for many Euro cars and top quality, this one should be the one for your MGB. 165f is correct, you gain very little if anything from a 195f in this old cast iron engine, 165f will give plenty of heat.

 
I've used the Stant Superstats with success for a few years. It wouldn't surprise me if they dropped their quality though. I would go for an AC Delco honestly. In over 23 years, and over 40 cars I've never had an OE thermostat fail before 100k.
 
I bought a Facet thermostat from eeuro parts when I replaced the housing for my Saab. Made in Italy, works perfectly.

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I always buy oem superstants as they are still USA made. They are much heavier duty than the basic thermostats. Although recently my last purchase at NAPA supposedly according to the sales guy their premium thermostats are made by Stant in the USA
 
Wahler is OE for many Euro cars and top quality, this one should be the one for your MGB. 165f is correct, you gain very little if anything from a 195f in this old cast iron engine, 165f will give plenty of heat.

I can't agree with that assertion for several reasons:

1. I have measured vent temperatures with a 195 vs. 165º Tstat and the 195º not only feels warmer but also gives higher vent temperatures

2. OE Spec was 180ºF for water/antifreeze. 165º was only specified for alcohol

3. I have found the engine to run better at 195ºF. When tuned for appropriate mixture at speed/under load, I can show lower CO emissions at idle keeping all else constant. Aside from that, at 165ºF, I never could tune out the high-RPM-under-load(i.e. interstate driving) lean running condition while also avoiding going overly rich at lower speeds, whereas it's easy to do with the hotter Tstat
 
Its your car, do whatever you think is right. Do some research on why they used a 180f for the USA and why 195f can actually cause additional engine wear and lower power. Lot of technical papers and info out there. I went through this with a 66 Mini and 65 Lotus Cortina.
 
Its your car, do whatever you think is right. Do some research on why they used a 180f for the USA and why 195f can actually cause additional engine wear and lower power. Lot of technical papers and info out there. I went through this with a 66 Mini and 65 Lotus Cortina.

Would you mind pointing to these technical papers?
 
Another mention of good service from a Stant Superstat. I've had one in a an old slant 6 in my '82 Dodge truck for about 4 years. If I correctly recall the advertising on them, they are sort of a leaker type that gets some heated coolant to the radiator sooner? With the Superstat, it surely seemed to take longer to get the coolant up to full operating temp.

It used to be easy to get a working t-stat, usually. I once had to try 3 different brands to find one that actually worked off the shelf. The winner was the cheapest one available and I don't recall the brand. That was about 15 years ago on an Altima.
 
A B Block is only a hill away from a blown headgasket - I always ran a 160 or whatever back in the day.
Or cracks in the exhaust valve seat area which was also very common.
Would you mind pointing to these technical papers?
I will see what I can dig up, it has been a long time since I looked into these engines. I can tell you this much though, these engines were designed in the 30's and upgraded in the 50's.
Their cooling systems are inadequate at best when brand new, running a 165f thermostat usually results in a 180f stable running temp.
Modern engines run much hotter with higher pressure systems and are more efficient for it but these old timers are a totally different animal.

At one point they were grinding the bores slightly oval (I forget the reasons) higher temps would cause slight binding in the bores and excess wear, the grey high graphite iron head did not like higher temps and were prone to cracking at the valve seats.
These engines used 7lb caps and later 14lb unlike modern systems that us up to 21+lb, had grease fittings on the older pumps and packings for pump seals. Old English engines were finicky when new at 50 years old, well you know.
 
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