PDA

View Full Version : TR2/3/3A Thermostats in Hot Summers and Moderate Winters



Tropical TR
07-22-2015, 02:13 PM
Given that everything else which can affect cooling on a TR is in order (radiator/cap/shroud, pump, tuning/timing) one generally wants to have a decent thermostat. This is a much discussed topic on various fora as I have found: Traditional bellows vs. modern, modern with or w/o holed bypass plug, high flow vs. standard, and 160 (summer)/180 (normal)/190 (winter), etc. versions, brand performance (i.e., Stant, Robert Shaw); not to mention where they all might be made these days.

I came upon this article written by one of our Aussie TR friends which talks about Tridon High Flow thermostats and his investigations:

https://www.tr-register.com.au/Files/technical/Too%20Cool%20a%20TR.pdf

Over here, I believe Tridon is MotorRad under its own name and others. As I understand there is also a Stant high flow model available through Summit Racing/others.

https://www.motoradusa.com/parts-locator.aspx#

The TR2/3 manual specifies (original bellows) thermostat opening at 150 degrees and full open at 197, which is ca. 15 degrees beyond normal operating temperature. Does a modern thermostat need to start opening as early as 150 if it opens quicker? Should a"160" thermostat be used for hot/summer climates? Often, manufacturer sites (including Tridon in Australia) default to 180 degree versions for the TR2/3/4.

However, the author of the above article swears by the high flow 170 version and (according to him) it remains only about 25% open at 180 degrees, resulting in more operating flexibility as required.

When I parked my TR3A 17 years ago and put it into storage, it was boiling over after a drive from northern to southern VA. Who knows what it was then (in fact it was several things, probably least of all the thermostat...), but none of those potential culprits will be left when the car rolls again. Would be very interested in views of those who have visited the thermostat issue time and again as to what constitutes an efficient modern replacement for moderate to very hot weather, and what they think about the above product or something like it.

Regards,

Walter

sp53
07-22-2015, 02:25 PM
I have never been there, but Florida sounds hot. I think might just leave the thermostat out and let the water flow. Around here in Washington I need a thermostat in the winter because if I did not, the motor might not warm up or would take some time. IHM the thermostat is more for a cooler climate. I do run a sleeved 160 because that seems to work best around here. Do yourself a favor and get one of those newer Macy Garage Fans and the thermostat will not make much difference.

Tropical TR
07-22-2015, 02:31 PM
It can gets hot and humid but not as hot as the southwest. Thanks for the suggestions. I do have a Macy fan going into the rebuild.

Regards,

Walter

TR3driver
07-23-2015, 10:58 PM
Lots of variations in both opinions and experiences, as you've noticed.

Previously, I had my TR3A setup with a 12" Hayden electric fan (not the most powerful on the market but not the weakest either) and no mechanical fan. 180F Robertshaw thermostat, no sleeve, bypass left open. Once I got the radiator issues sorted out, it would stay cool even in 115F (which is too hot for me) city driving, and running 100+ mph in 100F heat. (Which is just the worst I threw at it, likely not the worst it could handle.)

My current TR3 has the same setup, except a regular 180F thermostat (Stant IIRC). I haven't had it out to the desert yet, but again after getting the radiator issues sorted, it has stayed cool in the hottest weather I've been in (around 105F stop-and-go on LA freeway). The fan is set to come on when the water coming back from the radiator hits 190F, and only comes on when stopped or moving slowly (under 25 mph), then runs for less than a minute before shutting off again (about 185F at the water pump inlet). The needle on the gauge never quite gets past the '5' in "185" at the center (and it tests reasonably accurate) although it does wander between the '8' and '5' before the fan comes on.

When I was having radiator problems, I experimented with several setups, including bypass fully blocked and partially blocked; thermostat removed, thermostat disabled in full open position and so on. None of them made enough difference to argue about.

Obviously, my opinion is that the only reason for the low initial temperature on the original thermostat is because the aneroid (bellows) design took SO long to open. They had to make it start low, in order to have it fully open before boil-over! A modern wax pellet type doesn't have that problem.

Also, my feeling is that no thermostat is a Bad Thing, as it (should) mean the engine will never warm up fully under cooler operating conditions; leading to rapid wear, excess fuel consumption, oil contamination, etc. Racers get away with it because they don't care about those things, but I really don't want to have to rebuild the engine every 1000 miles or change oil every weekend.

Geo Hahn
07-24-2015, 10:14 AM
I run a standard thermostat (no bellows), a partially blocked bypass hose, a tropical fan and a radiator is good condition (recored about 3 years ago) but retain the crank hole. I think the thermostat is 170. That combination has been sufficient for good cooling in 100+ weather.

TR3driver
07-25-2015, 01:20 AM
but retain the crank hole.
Forgot to mention, in both cases I did not have the shop install the crank hole, as they said it reduced cooling capacity by about 10%.

The TR3 also has a 7 psi cap rather than the original 4 psi; and has a coolant recovery bottle installed. Previously, I could never get the original "long reach" radiator cap to pull water back from the bottle, so this time around I had the shop install a neck to suit a modern "short reach" cap (Stant Lev-R-Vent).

With the stock setup, the water level can not be at the top, or it will just get expelled when the engine warms up (water expands with heat faster than metal does). Main reason I wanted a recovery bottle is so I can fill it full and know something is wrong when it doesn't stay that way.

I also had the shop reinforce the areas that always seem to crack for me, around where the extension meets the upper tank, and the upper hose fitting. They laid soft 1/8" copper tubing into the seam and soldered it to both surfaces. So far, it seems to work well, no cracks in 5 years and 40K+ miles. (I recently retired, so don't drive the TR to work every day any more.)

Tropical TR
07-25-2015, 06:41 AM
Thanks, Geo and Randall. This is very helpful. I just picked up my re-cored radiator from the shop, opting to keep the crank hole but getting a core with five tube rows (staggered) and louvered fins. The very traditional shop owner (going strong at 75) did a beautiful job taking it apart - including fittings, data plate, etc. - bashing out the bottom tank, making the inlets/outlets round again and re-soldering all including the neck. The good core and the Macy fan should hopefully compensate for the retained hole.

Will try the Stant SuperStat thermostat which is still made in the US.

While not keen to go for a recovery bottle mod at this point, I notice that our Brit vendors do sell a 7lb., one inch cap for the necked TR4 radiator. Any reason not to use that on a TR3A with 86mm pistons?

Finally, in a non-freezing climate, would a water/anti-freeze mix of 2/1 or even 3/1 help heat transfer while still providing sufficient corrosion protection?

Regards, Walter

Geo Hahn
07-25-2015, 03:59 PM
I use 3:1 in a climate that does not freeze.

I do not know if that cap will draw coolant back in to the neck. I use a recovery bottle on my TR4 because its radiator has no neck and so any 'air' is at the top of the core. The usual (later) TR bottle & bracket are available form the usuals.

RC64
10-25-2015, 08:17 PM
I run a standard thermostat (no bellows), a partially blocked bypass hose, a tropical fan and a radiator is good condition (recored about 3 years ago) but retain the crank hole. I think the thermostat is 170. That combination has been sufficient for good cooling in 100+ weather.

Geo...

I can't seem to find it now, but I thought a saw a comment by you in a different thread where you mentioned the Tridon TT2000-170 high flow thermostat. If you've used that one were you able to find a source in the USA?

Rick...

Geo Hahn
10-25-2015, 09:17 PM
...thought a saw a comment by you in a different thread where you mentioned the Tridon TT2000-170 high flow thermostat...

Not me.

GTP1960
10-26-2015, 09:06 AM
The fan is set to come on when the water coming back from the radiator hits 190F, and only comes on when stopped or moving slowly (under 25 mph), then runs for less than a minute before shutting off again (about 185F at the water pump inlet)

Randall,

Do you have a special switch that is programmed for this function :

"and only comes on when stopped or moving slowly (under 25 mph), then runs for less than a minute before shutting off again" :

(or is it just the way your setup happens to works ?)


Guy