TR2/3/3A 187 NOS sleeved type thermostat

[sp53]

I took my newest project out and put about 20 miles on it. I did not like the temperature the motor ran at and the engine kept running on when I shut it down. At the gauge the needle was after 185 mark and that might have caused the running on. The thermostat is a 180 bellows type without the sleeve that slides to plug the bypass hole. Plus I have a tropical fan

I found a 187 NOS sleeved type thermostat and bought it on line in hopes it would help by plugging the bypass hole. In addition, I purchased something I had not heard about which is a “sleeve only plug” to be used without a thermostat from Moss. I guess they used that type for racing.

Anyways my question is let’s say I have a 160, 180, and a 187 thermostat: when they are all open completely once the engine is completely warmed up, are they all pretty much going to give the same reading at the gauge?

I remember David cooled off his motor after much effort with a different thermostat, but I cannot remember if it was the sleeve that helped or a temperature of the thermostat?

The car ran strong and really sounded tight, so I am happy with that; it felt like what I thought a new tr3 should.

steve

 

[CJD]

No...the engine will gradually come up to the approximate temp of the thermostat rating. Remember these mechanical gages may not be the most accurate unless you calibrated them recently. Once at the rated temp they should hold there...at least until you stop at a light for several minutes in warm weather. During long stops if you are running the stock radiator and fan, then the temp will start to creep up. This is a limitation of the cooling air through the radiator, though, and is not the thermostat's fault. Once a thermostat is fully open, it cannot do any more.

It sounds like you have followed some of the discussions on the skirted vs non-skirted thermostats. Adding the skirt or restricting the bypass may help fractionally with cooling...but it never stops a car from overheating totally.

 

[Hamish Racing]

My car runs between the 185 and the next mark (207 ?) as standard the elec fan brings it down.
Even at the 207 mark it’s not “boiling” so not over heating.

you say it’s a new project. Is it a new engine as a tight engine will generate more heat.

as to the running on I would check ignition timing -( this can make engine run hot too if it’s out)
and use a higher octane fuel to see if that helps.

 

[TuffTR250]

My TR3 will run-on if I use regular fuel. As a result I now use 93 octane unleaded all the time and it runs better and does not run on.
Bob

 

[sp53]

'Once a thermostat is fully open, it cannot do any more."

So what I am hearing is that a tr3 with 160 thermostat fully open is the same as a tr3 with a 180 thermostat fully open because they are both are fully open and doing all they can. Tr3s run hot from the factory and it takes modification to cool them down, and Yes for sure gauge calibration is always an issue.

Yes the motor is new, so maybe after the break in it will cool down some. When the new thermostat racing sleeve comes, I will put that in and run the motor without a thermostat and report back.

There was a tread some time back where someone put some Dawn dish soap in the radiator then ran the motor to clean out oil deposits in the radiator from a blown head gasket. I might do that also because I took both tanks off the radiator and when I soldered them back on I did not get all the soldering flux residue out of the radiator. Anyone try the Dawn dish soap idea?

steve

 

[bobhustead]

There is no need of a thermostat, blanking sleeve, or bypass block at all, unless you need heat in winter. I ran the TR3 I had in college without, and my current car has been on the road since 2012 without. No issues.
Bob

 

[sp53]

Bob What temperature does your car run at without a thermostat?

 

[bobhustead]

Usually remains at 185 or below. I am in NC mountains. It goes higher after a while uphill. It does not boil. It does not get to 212. Even fully open, a thermostat restricts water flow. Up to the point that a radiator is at maximum capacity for exchange of heat with the air, the more rapid the water flow thru the radiator, the more cooling from radiation into the air. Blocked water flow increases the heat retention upstream of the blockage. That is the purpose of a thermostat in the first place.
Bob

 

[DavidApp]

My TR3A seemed to follow the thermostat temperature rating. A 160 thermostat gave me about 160 and now I have a 185 thermostat, During the colder months in Georgia I run a bit below 185 and in summer 185 or a few degrees above.
My bypass is partially blocked.

David

 

[bobhustead]

Engine temp following the thermostat is the normal function of a thermostat. If water is not allowed to flow until you hit 160, your minimum operating temp will not be less than 160.

Bob

 

[2liter4cyl]

Engine temp following the thermostat is the normal function of a thermostat. If water is not allowed to flow until you hit 160, your minimum operating temp will not be less than 160.

Bob

The number on the thermostat is telling the temp when it BEGINS TO OPEN. If you use a 185, it may be running 195 (hot) before it is fully open. I use a 160, gives time to open near 185.

Hang one in a pan on the stove and see for yourself.
.

LeT

 

[bobhustead]

Usually remains at 185 or below. I am in NC mountains. It goes higher after a while uphill. It does not boil. It does not get to 212. Even fully open, a thermostat restricts water flow. Up to the point that a radiator is at maximum capacity for exchange of heat with the air, the more rapid the water flow thru the radiator, the more cooling from radiation into the air. Blocked water flow increases the heat retention upstream of the blockage. That is the purpose of a thermostat in the first place.
Bob

I just went into town, about a 10 or 12 mile round trip. Air temp is 78, humidity 50. On level roads, it ran right on the unnumbered hash mark between 90 and 185. Last two miles is significant uphill and it ran right on the "1" in the 185.

Bob

 

[Graham H]

I run my 3A much the same as David App, these cars were designed to have a thermostat and I wouldn't recommend running without one, also I have noticed if the engine is hot and the idle speed is too high it sometimes will run on when I shut it off.

Graham

 

[sp53]

I have a daily driver tr3 with a 160 thermostat a record radiator with the crank hole plugged. This car runs right at 1 in 185 very steady.

The project car has a stock radiator with crank hole that I rodded out and a tropical fan. The 180 thermostat I put in was tested in hot water and was fully open at 180. The motor is new and the idle is a little high, so I think Graham is right about the run on and maybe a the plugs carboned up also. I guess I am trying to figure out if the NOS 187 Smiths I bought would function the same as a 160 in a typical tr3 because they run hot.

I probably should have purchased an over the pond 160 and tried using that, but I do not trust aftermarket stuff much and could not pass up the nos Smiths for 35.00. Anyways I will play around with it and see. I had a good mechanic once tell me to always run a thermostat for even cooling of the motor so the front of the motor does not get more cold water than the back, but these are old school V8 guys. But again a tr3 has running hot problems, so I am going to try running no thermostat to see what happens in the summer plus it should make drain the crap out of the radiator better.

I believe in the summer no thermostat would be fine, but again I drive all year round. I did find with a 160 thermostat around here in the mountains the engine will cool off too much and die going downhill for a long time.

Steve

 

[TomMull]

In my youth it was common practice to throw away the thermostat at the first sign of overheating. It almost never helped the thermostat would be required again in the Fall again to get the heater to blow anything but cool air. Then, during a very brief stint as a "professional" mechanic, I was corrected and told that the function of the thermostat was to keep the engine at a constant temperature and to get it to that temperature as quickly as possible because the tuning was sensitive to the engine temperature. It was therefore, not a good practice to run without one.
I'm sure that is true in principle but whether or not it would make a noticeable difference in an old TR3 in the real world is certainly debatable but I have always used since then.

I also think that my TR3 runs better with the bellows type thermostat I put in a few years ago but I think the price I paid for it may have influenced my judgement.

Tom

 

[TFB]

I was lucky enough to have a relatively new tr3,6 years old,as my first car in 1968-1971.
With 30k it never overheated and sat in plenty of nj traffic with 80/90 summer temps common.
I think the thought that these cars have overheating problems is from people running old radiators.
I cant recall anybody having temp control problems that also had a new or recored radiator.My current tr3 with a alum wizard and elec fan with mech fan eliminator could be run without a fan at all if I needed to as the fan rarely comes on.
Tom

 

[sp53]

I put in my Moss racing sleeve that basically shuts down the by pass and runs no thermostat. The weather here is over 100 which is crazy hot for western Washington, but I took the car out anyway to see. It ran a little cooler without the thermostat, but not much.

Heck I forgot what a hassle it was to replace the thermostat. I would love to hear those designers explain that apron and radiator underneath it with the top radiator hose so short and flex able. The English had form before utility. Oh ya the sleeve did not fit; big surprise. My first fix was to double up the gasket and that did not work. Then I found a front housing piece that had a grove for the thermostat that combined with the grove on main body of the hosing provided enough room for the skif#$.

Anyways I am going to get one of those paper duct systems the engineers came up with to close off the big mouth cars for cooling. My small mouth runs way cooler. I have never put one of those paper board ducts in before, I guess take the grill off and fit it up. I have seen pieces of them in old part cars I bought. For my way of thinking the small mouth apron probably costs twice as much to build.

steve