View Full Version : TR2/3/3A Running Temperature of TR3

04-02-2006, 09:42 PM
I have had two weekends in a row where I actually just drove the TR3. I got in, turned the key, pushed the starter, and drove around! No work of any kind (OK, I tinkered a little). Of course, I am knocking on my wood desk as a type!

I do have a question, however, about the correct running temperature. As you all probably know, it gets pretty hot here in Austin, and the temperatures are starting to climb. Today was in the mid 80's while I took a 30+ mile drive. The temperature reading was a little above the 185 mark, which is dead center in the gauge (I assume this is a standard gauge). For a period of time, I was going 65-70mph (with Overdrive engaged) and the temp climbed a bit (although it never reached the next line on the gauge). After that, I spent a few miles on a side road going 40-45 miles per hour and the temp dropped a bit, but was still a bit above the 185.

I think this sounds pretty good, but I have read on this forum and others that the car should not run above 185. I am wondering if everyone thinks this sounds OK. I am about to enter into a hot part of the year and my eye will probably spend as much time on the temp gauge as it does on the road.

For your information, I do not have an electric fan. When my father had the car, it was removed when he upgraded to one of the better water pumps, and it actually ran cooler without it.

Thanks for your input.

04-02-2006, 10:06 PM
I will use a 160 thermostat in my 3 in the warmer time of the year. The temp will be around 185 when moving at speed. I installed a electric fan to keep the slow speed temps down.


04-02-2006, 10:57 PM
Hello, Spine, just today I took my '59 3A for a spin; spent the afternoon doing errands around W. Los Angeles, in some fairly slow stop and go traffic (like always, around here).

Like your car, I don't run an electric fan; in the past year, I've boiled out the radiator, back-flushed the engine and heater core, and installed a 6-blade yellow fan. I run a 50/50 mix, with Waterwetter. Just last week, I installed my rebuilt water temp gauge.

After it warmed up, it hung just a tick above the 185 mark; I have the 180 thermostat. It was fairly steady at that mark, with an ambient temperature of 68-70 degrees. I also picked up a Sears digital laser temp indicator this afternoon.

While reading just above that 185 mark at the gauge, the digital indicator read 177.6 at the thermostat housing, so I was happy reading that. Like you, I'll keep an eye on that temp gauge, as it warms up outside... Hope I've been of some help!

Best, Kevin Browne
'59 TR3A #58370

Geo Hahn
04-03-2006, 11:27 AM
Mine runs at the 185 mark pretty much all the time unless I get caught in slow traffic on a hot day. This is driving in Tucson and up a 9,000' mountain so it can get warmish. Here is what I have done:

Air Dam -- added to scoop air against the lower third of the radiator. Ever notice that a big hunk of the radiator isn't in the air flow? I think this helps a lot at speed.

Electric Fan -- installed as a 'pusher' in addition to the stock fan. I control it with a manual switch, mainly used at long stoplights and slow traffic. It is the cheapo from the FLAPS and installed using a set of clamping bolts so it can be easily removed. Wired into the horn circuit w/o a relay -- never been a problem.

Water Wetter -- added to the coolant. Added bonus(?) is that it will find any little leaks you have.

25% Coolant -- as I am not concerned about freezing I can reduce the % of coolant to what is supposedly a more efficient mix for cooling.

Blocked Bypass Hose -- controversy here as some think this can cause problems with the head. I have used this for 20 years w/o such problems. Blocked with a 3/4" copper pipe cap with a 3/16" hole drilled in it to allow some flow.

Ductwork in place -- the stock cardboard air deflector is in place in the front apron.

Overflow bottle -- on the TR4 it was easy to add. Haven't done this on the TR3A yet though some say the radiator cap can be modified (adding a sealing gasket under the lip to maintain vacuum) to draw coolant back in as the engine cools.

Fan Blade -- I'm using a TR4 (square ended) fan blade on the TR3A (stock is rounded ends).

Things I haven't done: 1) Change the TR3A radiator to one w/o a crank hole. I still use the crank and prefer to keep the original set-up. 2) An up-graded water pump I have heard about but not pursued. 3) Changed to a cooler tstat.

All this assumes that the radiator and block are clean and engine tuning, esp timing, are correct.

I've got some pictures of the air dam and electric fan mounting if you need them. I can also explain the blocking of the bypass hose if you are not familiar with that.

04-03-2006, 09:55 PM
I'd suggest acquiring a laser thermometer and shoot the top radiator hose for a comparison as the gauges are not known for their accuracy.

Don Elliott
04-04-2006, 09:10 AM
Running a bit above 185 won't hurt. Water needs to stay below 212 deg. F where the heat transfer coefficient changes when the water changes to steam. But a 25% antifreeze mix probably moves this up to 220 deg.F. And a 4 psi pressure rad cap will move the boiling point up to about 130 deg.F. So don't worry unless you are caught in traffic for more than 5 minutes when it may get to this temperature. That's when you need to have the electric fan. My fan is a 12" ducted Kenlowe fan from England pushing air through the rad.

I believe that when they needed to add the cross pipe for rigidity after the prototype TS-2000 (the first car shown with the rounded tail), they had to feather the pitch on the fan blades for it all to fit. This fan doesn't do much to pull air through the rad when you are idleing at 600 RPM.

04-05-2006, 06:57 AM
I changed mine to R&P steering a few years back so I had to go with an electric fan at the time. The fan that I put on at the time was OK except in traffic on hot Florida days. Last year I put a second fan on it (one push one pull) wired them to a 190 switch and a 165 thermostat and that took care of the problem. Be sure to check the gauge, mine reads about 20 degrees high which prompted a new core that I didn't need. A laser thermometer is cheap compared to a core. I also run water wetter and about a 90% mix of water. Freezing is not a problem here. I do not have the bypass blocked but will do that next time I have the hose off.