TR2/3/3A Water Temp

What water temperature is common among TR3 owners with the original radiator and fan? Book says you shouldn't exceed 185 degrees but I can't keep mine under that. Is an electric fan the only solution?

I don't have solid proof, but it's my belief that you should be able to keep it down to at least roughly that range. However, the original radiator seems to be subject to a strange kind of failure; so you may have to install a reproduction or have yours recored.

With modern radiators, the fins are soldered to the tubes to ensure good heat conduction. Obviously, the hot coolant is in the tubes but most of the available surface area is on the fins, so those joints are critical to cooling. But with the original radiators, the tubes are just pressed into holes in the fins. On TS39781LO, the joints had become loose or got dirt/corrosion/paint in them, or something; such that the tubes weren't in good contact with the fins any more. It flowed just fine, only leaked a bit (at the extension), and I even had it rodded out. The car tended to run hot at freeway speeds when I got it; but even after dealing with the missing air duct, leaking head gasket and so on, the problem kept getting worse. When I finally had the radiator recored, all my cooling problems vanished like magic.

Of course, by then I already had several other modifications, electric fan, wax pellet thermostat and so on. So I can't swear that a bone stock configuration would work as well. But "back when", I never had cooling problems at speed. And as I recall, none at idle as long as the mechanical fan was in good condition and I didn't let it sit idling for long periods.

Much the same scenario played out again with my current TS13571L. It wanted to overheat in heavy stop-n-go traffic when I first got it together, so I put the recored radiator & electric fan from the previous car on it. Overheated even worse! And again at freeway speeds, not idling. It turned out that the inside of the radiator tubes was coated with some sort of "mud" that was blocking heat transfer. Probably from the stop leak I used to counteract the crack around the extension. The shop couldn't even get the rods through it! When they finally forced the rods through, it leaked in multiple places, so I had it recored again. And once again, all my cooling woes disappeared. It doesn't creep up at all, even in 115F ambient (tho the driver definitely boils over at that temp!)

Last I heard, Modine no longer makes the core that fits our radiators. But there is a shop in my area that can custom-make them to any size, for only a bit more money. Likely they can in your area too; having a radiator recored is a common operation on big trucks. Last time I asked, the cost was comparable to a Wizard aluminum radiator (but I like brass because they can often be repaired where aluminum can't).

I also discovered a secret for keeping the extension from cracking. My radiator guy laid a length of 1/8" soft copper tubing into the corner, so it touched both tanks all around the extension, and soldered it to both of them. Once it's painted, it's almost unnoticeable (looks kind of like a sloppy solder joint).

I decided to flush the radiator with clean water however in order to drain the old mix I had to remove the entire tap since the ball valve was frozen. I didn't want to force it open. In removing the tap, I must have disturbed the fitting it screwed into and it developed a small leak. With just water in the radiator the car ran cooler than it did with the old mix. It idled below the 185 degree mark for several minutes. I couldn't drain the mix at the fitting on the block because that ball valve was also frozen. After draining the radiator for the second time I added the coolant and distilled water. However in order to stop the leak I knew of no other way than to add Stop Leak. The car then ran hotter than usual probably due to the Stop Leak inhibiting circulation. I'm hoping that by driving the car the circulation will get better but I think I'm being optimistic. I don't want to pull the radiator until winter.

Nothing wrong with being optimistic but in case the problem persists you might flush it once again and try to fix the leak at the fitting with Teflon tape or Teflon pipe dope rather than add something to the coolant.

On an old cooling system I usually avoid stop-leak products except in emergencies when I just need to get home.

Those petcocks can be replaced or may respnd to a soaking in PBlaster and being exercised a bit. My old arthritic hands have a hard time opening them even when the valve is fine, so I slip a long 1/4" drive socket over the handle to make an extension (I think the socket for a 3/8" nut is about right).

I used teflon tape on the tap threads. The leak is around the fitting that the tap threads into. The radiator would need to be pulled to fix that. It's probably brazed into the radiator. The car is running half way between 185 degrees and the next slash mark (whatever that represents). It seems steady at that point. I know a lot of owners go to the electric fan as a supplement or by itself. Can the car be expected to run below 185 degrees without replacing the core, an aftermarket radiator or an electric fan if the original radiator is in good shape?

If you had a heating issue before, then the stop leak will not help it. These are 2 cores, one clean, and the brown one is coated with stop leak. You can see it builds a rubbery insulating coating over all the wetted areas. A better way to stop a single leak if you don't have time to do it right is to rough the hole area and smear JB weld on it. It'll last until you have time to pull the radiator and fix it right, without coating the entire soloing system.

The TR2/3 cooling system is normally air limited. In other words, increase the airflow over the radiator and you make the biggest gain in cooling. Of course all the other items contribute, so they all need to be up to speed. But even if the entire stock system is working great, these cars still overheat when you sit a light for long times in summer. In cooler weather it will hold it's own.

Also remember the gage is rarely accurate...

According to the gauge my car is operating around 195 - 200 degrees. It is all original and I don't want to go to an after market radiator or electric fan. Do you think replacing the core might help or is it okay to run at that temp?

To touch again on the fins to tube connection.
I had a customer....worked at Boeing...had a Barracuda (early 70's) which I maintained. He got transferred to Florida for several years, they shipped his car, and when done, they shipped it back. He could not keep it cool. At all. Called me in.
Car had a flex fan installed in Florida to try to correct the issue....can had factory air, with condensor in front of radiator, and a full fan shroud.

I decided to pull the radiator for a boil out.

Drain, shroud back, hoses and trans lines off, pulled the radiator......and apparently the salt air (I know, never happens, right?) in Florida on the coast ate the fins off. As in, when I got the radiator out, there were tanks, headers, side straps and tubes...and no fins. They were gone. Remnants in the corners.

New core fixed all of his cooling issues immediately.

Funny how that works.

Another one.... Vega. Overheated on the freeway (well, anything above 30 MPH), and nobody could figure it out. Brought it to the shop, my guy had it idling...monitored the temp, never got about the thermostat value.

He was going to check something, someone had backed a car in close to the front of the Vega, so he had to turn sideways and shuffle between bumpers......and looked down, realized the shop rag hanging out of his pocket was blowing away from the Vega grille.

Vegas run the water pump and fan off the back of the timing belt. Someone had installed a flex fan for normal rotation...but on a Vega, it was backwards. The faster you went, the more the fan neutralized the air flow, so over about 30 there was NO air flow.

Proper fan from a junkyard fixed it.

You just never know.

IF that is all it does, you should be fine. As long as the coolant doesn't boil and the exhaust isn't glowing red, running at 200F won't be an issue.

But a lot of things affect both how much heat the radiator has to move, and how much airflow it gets to move the heat away. One example is when you've been running fairly hard (eg cruising the freeway) and pull over for a break. There is still a lot of heat in the engine and coolant, but no airflow at all. If the system is already near boiling, it will probably boil over and loose coolant.

Heavy stop n go traffic is another particular problem, and you never know when it might strike. We were stuck on I44 for some 20 minutes yesterday, in a section that normally just slows way down.

I can't say for sure whether having it recored will help, but it seems very likely to me.

You might also want to double check the gauge. They often read high, especially if the engine has been overheated in the past.

frankfast said:

According to the gauge my car is operating around 195 - 200 degrees. It is all original and I don't want to go to an after market radiator or electric fan. Do you think replacing the core might help or is it okay to run at that temp?

Click to expand...

Steve pointed out that some radiators have 5 rows of tubes and others (likely previous repops, only have 3. After removing the crank hole, adding 2 more rows of tubes should be a decent increase in radiator cooling.

Still, I have 5 rows, super clean 83mm engine, new water pump, with timing and mixture up and rich...and my TR2 will still run hot at stop lights. Of course, it is over 100 degrees ambient, but my point is these cars lack airflow. As soon as I start moving the temp comes right back down. Since I would rather keep the car original, I counter the heating by shutting the motor off if I will be sitting 2 minutes or more.

Thanks for your advice. I've decided to have the radiator recored. It's just north of $500 plus the labor to take the nose off. Without a lift, I've decided to let someone else do the work. I hope that there's an improvement.