TR2/3/3A TR3 Over heating

I have the same issue as many with keeping my 1959 TR3 engine cool while at idle after running at speed. I am looking for feedback from anyone who has actually dealt with this issue or just general running hot issues. Did you add an electric fan? Did you replace the stock fan blade. Which fan did you use? Did the installation require customization? Is the performance what you expected? Any comments are appreciated.
Thank You

I removed the stock fan, and replaced it with a 12" (IIRC) Hayden. Now the _only_ time it heats up is if I turn off the key (disabling the fan) immediately after driving at freeway speeds. Next time around, I'll build or buy a fan controller that allows the fan to run for up to 5 minutes after key-off.

When I originally did this to my 59 TR3A, I used the plastic pins through the radiator to mount the fan. Based on my radiator guy's advice, I tried to route the pins away from the tubes, but I'm not convinced it made any difference.

Second time around, on my current 56 TR3, I had the radiator shop add tabs to the radiator to mount the fan.


As a side comment, when I first added the fan to the TR3 (by moving the entire radiator and fan over from the wreck), it overheated badly. After several go-rounds and much investigation, I finally insisted that the radiator shop rod out the radiator, even though they said it did not need it. Turns out they were wrong! Although none of the tubes were totally blocked, they were all coated inside with some sort of gunk (probably stop-leak mixed with rust), to the extent that they could not get the rods through. When they finally managed to force the rods through, it started leaking in 6 or 8 places, so I just had it recored. All my cooling problems disappeared like magic. The moral of the story is : Always have them rod it out, even if they say it "flows fine"!

The only downside is that the original generator cannot keep up with both headlights and radiator fan. It's only an issue if I get caught in a traffic jam after dusk, and I usually deal with it by flipping the lights off and bumping the idle up with the choke knob. More recently I've installed a pair of LED headlights, which help a lot since they only draw about 3.6 amps on low beam (for both of them), instead of the roughly 10 amps that my old H4 Halogens were sucking. They do look a little odd, the light is very white instead of the yellow of the old headlights, but they do put out a bunch of light without getting in other's eyes.

TR3driver said:

I removed the stock fan, and replaced it with a 12" (IIRC) Hayden. Now the _only_ time it heats up is if I turn off the key (disabling the fan) immediately after driving at freeway speeds. Next time around, I'll build or buy a fan controller that allows the fan to run for up to 5 minutes after key-off.


The only downside is that the original generator cannot keep up with both headlights and radiator fan. It's only an issue if I get caught in a traffic jam after dusk, and I usually deal with it by flipping the lights off and bumping the idle up with the choke knob. More recently I've installed a pair of LED headlights, which help a lot since they only draw about 3.6 amps on low beam (for both of them), instead of the roughly 10 amps that my old H4 Halogens were sucking. They do look a little odd, the light is very white instead of the yellow of the old headlights, but they do put out a bunch of light without getting in other's eyes.

Click to expand...

Hey Scott,

My overheating problem lead me down an extensive modification route.
but first thing I did was to flush my old rad. & engine with Evaporust HD flush stuff 3 times.
Not to clear the rad. As much as to reduce the crude that builds up around the water jackets.
especially behind # 4. (using a laser thermo sensor, I found it was always about 10* hotter there than anywhere else).
It helped, as my dieseling problem went away.
after that I replaced the water pump with a 6 vane, new bellows thermostat, replaced the radiator with an aluminum one, & like Randall, installed a 12" puller fan ( removing the old crank fan & hub, by going with the moss harmonic pulley small belt conversion).
Now she very rarely goes above 190* even without the fan kicking in.

my logic was driven by general laziness. As I do not want to rework the front of the engine compartment again anytime soon, so I did a lot of preventative maintenance stuff.
(apron off-phobia)

Randall, two questions:
If you figure out how to run your fan on a ignition off, five minute delay, pls. Let us know!

Regarding LED headlights: was there any modifications involved( new housing etc.). Also what brand are you using?

thanks!

I had a 2.2 liter kit in a TR3 I drove daily in Miami. I cured the overheating (in a completely rehabilitated cooling system) by completely removing the thermostat. I did the same for the one I drive now in NC. Many posts on this site propose that you can't do that. I have had no adverse effects. I have done the same on all manner of other vehicles. When I was a line mech ay a BMC dealer in Miami, air conditioned MGBs had horrible overheating. The factory provided a device to replace thermostats called a blanking sleeve (an open brass sleeve with holes drilled in the sides). Worked fine. There came a shortage of blanking sleeves and we did a few by simply removing thermostats. No problems ensued and we stopped using the blanking sleeves altogether. If you get a new radiator, get it without the crank hole as this will add three circulation tubes.
Bob

There are many approaches to the cooling issue - with several seeming to lead to successful results. The starting point, of course, is to have the system in good nick - then it is a question of what to do to improve the stock set-up.

I use a 'tropical fan' which moves a lot more air than those flattish butter paddles that the TR3 came with:



Although the apron is off in that photo, I was able to originally install it with everything in place using a Gearwrench and Locktite on the bolts.

I also (mostly) block the bypass hose with a copper plug:



There are a few other things but those are the two that I suspect (can't really prove) are most effective. Even with the hand crank hole in the radiator the engine never overheats in Tucson traffic or climbing mountains.

BTW - I am also using the LED head lamps mentioned by Randall and they seem to work well with a much lower draw than the H4 halogens I was using.

GTP1960 said:

...If you figure out how to run your fan on a ignition off, five minute delay, pls. Let us know!

Click to expand...

My other British car has electric fans controlled by a thermo switch (aka an Otter switch). There is simply moved the power supply from a switched (green wire) circuit to an always hot (brown wire) circuit. That way the fan stays on awhile after engine shutdown. Particularly helpful on short stops like gas stations on a long road-trip.

Yeh you need to have a clean radiator first, either a new one, recorded, or rodded out, but something you are sure about, a flush out is too questionable.

Next you need a different fan. The stock fan will not be adequate in today’s driving, too much stop and go. My first choice is the original tropical fan from the factory, but they are rare. There is a vender who has made a fan just for this; I think it is Macy’s garage. That fan looks top notch, but I have no personal experience with it. I was against the electrical fans for the same reasons as Randall, but it sounds like he has figured out a way to make them work dependably with the headlight modification and some support for the fan.

On the thermostat, I use the expensive sleeved thermostat that blanks out the water pump routing after warm up, but if I lived in a hot place, I might just pull the thermostat out also. The people who schooled me felt the thermostat provided an even temperature in the engine by opening and closing. I would say these engines just run warm/hot in hotter weather. The cooling system on them is just not that good. There are some other body improvements also. The small mouth model runs cooler because the air is forced onto the radiator with built in ducting and if you have a large mouth they make a shroud to put in the grill opening to help force the air onto the radiator. You can cool them off, so keep it on the road.

Scott, after rebuilding my engine which also had the heating problem; I got rid of the stock fan and installed an electric fan like Randall's and also installed an thermo switch which runs after the engine is shut off. In addition I also installed a cutoff switch to cut off the power to the electric fan if I didn't want it running after the engine was turned off to save the battery. I replaced the generator with an alternator, which took care of the electric draw issue. I have not had any heating problems since I made those changes. Even driving in parades in the summer (which gets pretty warm here) the car has not run hot.

GTP1960 said:

Randall, two questions:
If you figure out how to run your fan on a ignition off, five minute delay, pls. Let us know!

Regarding LED headlights: was there any modifications involved( new housing etc.). Also what brand are you using?

Click to expand...

Sorry for hijacking the thread here, but hopefully not too much of a digression.

I enjoy experimenting with simple electronics, so my plan is to use a small microcontroller to implement pulse-width modulation for the fan (which I believe will reduce overall power consumption) as well as the 5 minute delay. Haven't decided which one yet, but there are many tiny micros around that would work fine for such a simple task. For example, the PICAXE-08M2 is attractive because it's cheap ($3 each for the bare chip, $30 for a development system) and comes in a package with old fashioned pins (much easier for me to work with than modern surface mount stuff).

https://www.robotshop.com/en/picaxe-08m-starter-pack-usb.html

Also here's a brief article singing the praises of PWM fan control
https://www.electronicmotionsystems.com/BPS_03-10_EMS_web.pdf

There may be off-the-shelf controllers that do all this, for example I just found the PWM85A which has a 1 minute delay
https://www.hollisterroad.com/proddetail.asp?prod=PWM85A
But I prefer to roll my own.

The headlights were totally plug-n-play, the only modification to the car was to re-aim the headlights after installation. I did buy new Hella H4 conversions as I wasn't all that happy with the Bosch units I had been running and the Hellas were on sale https://www.busdepot.com/0301600118
The LEDs are H4 replacements that I found on eBay https://www.ebay.com/itm/New-60W-60...006-HB2-HB3-/251680369697?hash=item3a9951ac21
They fit directly into the Hella conversions, except I had to bend the mounting spring slightly to get it around the heat sink. The little power supply lays nicely between the side of the lamp and the bucket, although it did take a little maneuvering to get it there. There are a few more photos at https://s258.photobucket.com/user/TR3driver/library/Misc parts/LED H4 replacements

(I really should remember to clean the bench up a bit before taking photos, please ignore the mess. Also, the schematic visible underneath has nothing to do with headlights, it was for some LED turn signal/marker lights that I was working on for the front. I didn't care for the result, so I need to rethink that one.)

PS, forgot to mention before, I deleted the crank hole many years ago and the radiator that came to me in my current TR3 didn't have one either. According to my radiator guy, having the hole reduces cooling capacity by about 10%, because the tubes are cut and blocked above and below the hole. With the crank hole deleted and a stock fan, I was only having trouble with the temperature creeping up during long traffic jams in hot weather. Coming home from TRfest 99 was when I decided to abandon the mechanical fan (again), but the traffic on the 101 was it's usual "parking lot" mess and it never actually boiled over even though it took us over an hour to go 20 miles and the air temps were close to 80F. I just got tired of worrying about it!

I just finished addressing this issue on my '58. I replaced the stock fan with the Macy's Hurricane Fan Blade. Then, just as an extra measure for those hot day red lights, I put an electric fan in front of the radiator that I control with a dashboard switch. I haven't had to use the electric fan yet, and my temp has stayed steady at around 185 when it used to get up to 200 fairly easily. I'm still using the stock generator. I did replace the headlights with modern halogens, and put in a relay system for them. I haven't tried running the electric fan and headlights at the same time, yet. I'll have to give that a try this weekend. By the way, you can install the Macy's fan without removing the radiator or the cowl. It's not easy - you have to disassemble the fan, install the hub, and then reassemble the fan. I highly recommend the Macy's fan.

Bill

bobhustead said:

I had a 2.2 liter kit in a TR3 I drove daily in Miami. I cured the overheating (in a completely rehabilitated cooling system) by completely removing the thermostat.
Bob

Click to expand...

you know, while I never drove mine with the thermostat removed, I had it removed while I flushed it.
i ran it at idle for a total of approx 6-7 hrs. & never overheated. In fact it ran the whole time at about 185 degrees( I had the idle set to about 1400 & I had a external industrial pole stand fan blowing on it at med. Speed). This was with the original crank hole radiator, Not the new aluminum one that holds a 1/3 more coolant and is "new".
P.S. I will also say that the flushes of the original rad. /engine were impressively rusty & progressively clear.

Geo Hahn said:

My other British car has electric fans controlled by a thermo switch (aka an Otter switch). There is simply moved the power supply from a switched (green wire) circuit to an always hot (brown wire) circuit. That way the fan stays on awhile after engine shutdown. Particularly helpful on short stops like gas stations on a long road-trip.

Click to expand...

At my age ( & my memory banks age) I am trying to reduce the # of things I have to remember to shut down.
my fear would be, if I moved the power supply to the unswitched side, and depended solely on the thermostat sender switch, it would "decide" to keep running the fan until the battery gives up. A triumph mechanic I talked to in St. Louis stated he had electric fans continue to run for as long as 15m after ignition off. Therefore a PWM with a timer on it sounds very attractive: Though, of course, it could fail too.

GTP1960 said:

my fear would be, if I moved the power supply to the unswitched side, and depended solely on the thermostat sender switch, it would "decide" to keep running the fan until the battery gives up. A triumph mechanic I talked to in St. Louis stated he had electric fans continue to run for as long as 15m after ignition off.

Click to expand...

That is my concern as well. However, in limited experiments with my current setup and turning the key back on, it always shut off in just a minute or two; even though I have the sensor mounted in the water pump housing. Apparently the water will continue to circulate a little bit just from convection, as long as the thermostat is open.

One of the problems I see with running without a thermostat is that the operating temperature is going to vary widely depending on ambient temperature (and other conditions of course). Running around in freezing weather (as I occasionally do up in the mountains), the engine will never warm up at all. Meaning, among other things, that you have to either drive with the choke always on, or set the mixture way rich. Actually, I see that problem even at 70F ambient, my current setup will just barely lift the needle from the peg cruising down the freeway at 70F with no thermostat.

Geo Hahn said:

There are many approaches to the cooling issue - with several seeming to lead to successful results.

I also (mostly) block the bypass hose with a copper plug:

Click to expand...

sorry to change the subject: George, your wire hose clamps look a heck of a lot better than the ones I just got from TRF. Original?

WOW!! Thank you for all of the great ideas. One of the things I love about old sports cars is the basic simplicity. I have been trying to avoid the addition of an electric fan but had almost convinced myself that was the only cure. I have been communicating with Mark Macy of Macy's garage and have ordered one of their Hurricane fans. I will be making three improvements that will hopefully cure the cooling issue. 1.Adding the Hurricane fan from Macysgarage.com 2. Adding an air shroud to get more natural air flow through the radiator 3. Adjusting the thermostat situation. Since keeping heat in the engine will probably never be an issue for this car I am going to go with Geo Hahn's idea of plugging the bypass. (If this does not perform to my liking next step will be the sleeved thermostat). I will post an update next week with the results. Thanks again for all of the helpful tips.

I pulled the stock fan without removing the radiator or cowl and planned to add the Hurricane the same way but since I am adding an air shroud now the cowl must come off.

ScottWyke said:

...since I am adding an air shroud now the cowl must come off.

Click to expand...

No need to remove the apron to install the fibreboard shroud. In fact, the installation sequence to put an apron back on is to install it before you put the shroud on.

You do have to remove the grille as well as the bumper and the supports for the bumper guards.

As for installing Mark's fan with the radiator in place - dunno, but worth a try.

GTP1960 said:

...your wire hose clamps look a heck of a lot better than the ones I just got from TRF. Original?

Click to expand...

Yes, original. No idea how they compare to repros available -- the most visible difference is that the screw has a round head, not hex.

ScottWyke said:

since I am adding an air shroud now the cowl must come off.

Click to expand...

I'll second Geo's motion. There's no need to remove the apron. It takes some fiddling to get the shroud to fit in place, particularly around the sides of the radiator, but it's not that difficult. There are several threads on the subject with plenty of photos and tips. Here's one...

https://www.britishcarforum.com/bcf/showthread.php?91521-Air-Deflector-Installation-Help-Needed

Run a search and you'll find several more. I installed mine awhile back and posted several photos but I can't seem to put my hand on that thread at the moment. If you can't find them let me know and I'll post them again.

Rick...

RC64 said:

I'll second Geo's motion. There's no need to remove the apron.

Click to expand...

Third. You'll never get it to fit right trying to install before the apron, the apron has to be in place first. Besides, it only fastens to the apron.

Assuming of course that you are talking about the factory shroud in front of the radiator.

Something that I didn't see mentioned : many of the TR3A repro grilles are too flat and don't have enough opening between the slats. The factory actually made a poorly documented change to bend the tabs deeper and open up the holes, but it seems most reproductions are made to the original plans. If you are having trouble with the temp gauge creeping up at higher speeds, you might try opening up the grille openings.

One other point (which perhaps you don't care about), a mechanical fan takes power (and fuel) to turn all the time, which goes up at higher rpm. Kind of a waste, since the fan is only needed when stopped or moving slowly. One of the big advantages of electric is that it only takes power to turn when it is needed.