• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

running hot

Share this page

gsalt57tr3

gsalt57tr3

Jedi Warrior
Offline
My TR3 seems to be past it's ignition problems, but now I seem to be running too hot. About 230 to be more precise. I've installed an electric fan on the front of my radiator, and I'm about to send it out to be boiled and cleaned.

What do people know about keeping their cool?
 
Is it running hot under what conditions, idle, highway driving, all the time. What engine modifiactions. What is your timing set at & your max advance. What changed from before to cause this.
This sounds good for a start
 
There are so many TR3 issues to think about. The easiest is to make sure that
1)There's enough coolant (remember, there's no catch tank, so coolant is expelled to the ground.)
2)The thermostat hasn't failed
3)The car isn't running way too lean (check the plugs for white residue or burning.)
4)That your radiator cap hasn't failed. I believe the TR3 cap is 4psi.
5)That your electric fan in front is pulling air to the radiator, rather than pushing it away. (or if you installed it behind, that it's pushing hot air away, not pulling it back.)
6) After that, it's possible your water pump is dying...or your temp gauge is off /ubbthreads/images/graemlins/wink.gif . My last TR3 (a '59) was always 15 degrees off.
 
Running hot was my obsession for six months. I solved it by: Installing an auxiliary fan; plugging the bypass; avoiding any "retarding" of the timing; avoiding an excessively lean carb mixture. Quite frankly, I think the trick was the combo of the auxiliary fan and the richer carb mixture. Those were huge. Plugging the bypass was probably a waste. Some folks swear that a lower temp thermostat helps (160 degree), but a good mechanic here tells me that's bunk. Good luck.
 
She overheats with highway driving.

There was plenty of coolent.
There was no thermostat.
She was running rich.
Radiator cap is fine.
Electric fan is pointed in the right direction.
Water pump is a consideration.
Temp gauge is right on. (Checked with IR reader)

What about aluninum radiators?
 
G,
To start with , I would put a summer thermastat in. 160 deg should be fine. The thought that no therm makes a car run cooler is usually not true. The therm also slows the coolant flow so it has time to disapate heat in the radiator. This would be more evident at highway speeds.
Water pumps are usually faulty when they leak, it is unusual for the impeller to corode to the point that the coolant flow cavitates or suffers but not imposible.
Extreme timing advance or retarding can cause higher water temps, double check this. You should notice poor timing in everyday performance, although most motors love lots of advance. Because you said highway speeds bring on the symtom check your total advance.
Certainly your radiator could be the cause. Also check your water temp with a thermometor, the sender or gauge could be inacurate.
 
I agree with trboost about the thermostat. There needs to be some restriction. If you want, you can remove the thermostat internal stuff and just leave the outer ring which will supply the necessary restriction. I believe that's what Kas Kastner did on the racing TR,s. There is also a lot of contoversy about the thermostat itself and the by-pass. The original type thermo opened and closed the by-pass along with opening and closing the flow to the radiator. Original types are very expensive (about $60). Does anyone know exactly what the deal is with this by-pass thing?? I keep reading conflicting opinions.
 
It seems to me several important points have been overlooked here......Is the heater valve at least partialy opened(gotta do it) Have you ever had the sleeves out of the block to clean out the crud that collects around them??
(it will bolck water flow badly over time) Have you verified the temperature as correct???(faulty gage) I recomend putting on a modern plastic fan in place of the old
lump(which get failure prone in their old age)this draws better air flow through the radiator solving most woes....
MD(mad dog)
 
Running hot on the highway is not a good sign. In general, the over heating problem is engineered right into a tr3 and usually the road speed provides enough cool air in which you would not experience the problem. In addition to that, it sounds like you have a small mouth and this provides a natural cooling shroud. I would have to say that the problem is an interior water pathway block in the engine or the radiator, but that should over heat all the time. The block or the head might be cracked. I would flush the block and have the radiator rebuilt at a good shop and have them fill in the crank hole with radiator core. This will provide maybe 15% more cooling. Get a good original thermostat. You can find NOS for maybe 40 to 50.00$. Then put on either a six blade metal or the plastic fan. See what happens. There might be one miracle thing to take a look at: Is there something actually on the front of the radiator like piece of cardboard or maybe the neighborhood cat.

Regards George
 
Hi,

I would bet dollars to donuts that the missing thermostat is the problem.

Without a thermostat, TRs move the coolant through the radiator too fast for proper cooling to take place. These cars should never be run without a thermostat (or similar restriction) installed.

Your statement that the problem is occuring more at highway speeds supports this: higher rpms move coolant even faster and the increased flow of air isn't solving the problem.

Install a thermostat. If you can't get an original-sytle sleeved one, likely at a ridiculous price, get a standard cheapie in the 160 to 180 degree range and restrict flow to the bypass hose. To do that, get a metal spacer or something that reduces the size of the bypass to about 1/4 or 3/8", by inserting it into the hose. Be sure it's a snug fit inside the hose.

Another way to achieve some limited bypass is to drill a small hole in the flange of the thermostat. Some thermostats come with this already done. Some bypass is important until the engine warms up and the thermostat opens to it's warm operating position, so I'd avoid completely blocking the bypass hose completely, although some folks seem to have done so and not yet had a problem.

By the way, if your water pump is turning freely and not leaking or making noise, I doubt that it's a problem. There are upgraded impellors, with 6 blades instead of 4, that racers use. However, this is not likely something you would need unless you regularly run the engine above 5500 or 6000 rpm. The special impellors are as much to prevent cavitation as to increase water flow, and are often matched up with a high volume radiator to be effective.

Also, pusher fans mounted on the front of the radiator are less efficient than puller fans mounted behind the radiator. I've seen some speculation that they might even hinder airflow. Of course, if you are still using the stock fan behind the radiator, for authenticity's sake, you don't have much choice. If you ever opt to move the fan behind the radiator, the original fan needs to be removed, but the hub assembly and heavy extension retained because it also provides dampening to the crankshaft.

Do you have radiator shrouding in place to direct air flow into the radiator? I think missing shrouding is more a cause of overheating in TR4s than TR3s, but it still might help.

I agree with other responses that too lean a mixture or incorrectly set timing might be part of the problem, too. Perhaps the car is running rich at lower speeds, but lean at higher rpms.

I also agree that a faster opening "Summer" thermostat doesn't really solve a cooling problem. It's just open sooner and will have lilttle or no effect on the cooling system, ultimately, once fully warmed up. An open thermostat is the same, no matter what it's initial operating range. The 180 or 190 degree will help the heater come up to temperature more quickly in the Winter, but that's about it.

I happen to have a 160 degree stat in my car, but just because it was the only size of original sleeve-style thermostat I could find when I was looking. I'd be just as happy with a 180 degree thermostat.

The primary reason to install an aluminum radiator is to reduce weight. Sure, some are built with many more channels than the original TR's 20, and might cool better. But, aluminum is less efficient than brass at conducting heat away from the coolant. So a larger radiator with more total cooling area is needed, to achieve the same level of cooling.

Does your radiator have the crank handle hole? If so, that reduces the radaitor's cooling area by a significant amount, 20% or more.

Hope this helps! Let us know.

Alan
 
One additional item to check is the condition of the hoses. Particularly the radiator outlet hose. These can come apart internally and be sucked flat or partially blocked by the water pump. The increased engine rpm at highway speed would correspondingly increase the pump suction. As many have said, the TR3 doesn't usually over heat at road speed because of ram air cooling makeup for the pitiful fan performance.

If you are considering partially blocking the by pass between the thermostat housing and the water pump, I've found a pretty good item to use. A tire valve stem for a tubeless tire wheel works well with slight modifications. Remove the valve assembly and cut the screw cap end of with a hack saw and discard. You want the remaining piece to be about an inch or so long. There is a brass tube in the center that needs to be punched out, don't want that coming free and running around in your engine. The tapered end should fit and wedge nicely in the water pump connection with the fat end being larger than the bore and smaller than the I.D. of the hose. The hose should fit right over it and attach normally.

Good luck in resolving the problem.

Safety Fast,
Dave
 
1 MINOR detail that I overlooked due to being a novice TR3 owner.

My car is a TR3, BUT, at some point in its history it has had a front end accident, too late in history to get a TR3 nose. She has a TR3a nose, WITHOUT any kind of shrouding to direct airflow to the radiator. Air was free to flow around the radiator at will. This, and the thermostat problem, will be corrected by tomorrow.

I do have a crank hole in my radiator. We will see what effect the current corrections have before filling the hole with core.

Thanks all!
Glenn
 
Hi again Glenn,

Just a thought....

Radiators aren't too hard to find used. For example, they show up on eBay with some regularity.

Rather than plugging the hole in the one you've got, I'd suggest tracking down a "no-hole", long neck version, have it rebuilt at a good radiator shop and swap it in. Then you could keep the original as is, with the hole, in case originality ever becomes an issue and you want to swap it back. The radiators with the hole seem to sell for more than those without, and I would imagine it pretty hard/expensive to install a crank hole in one that lacks it.

Over the 25+ years I've owned the car I've done a lot of modifications on my TR4, for fun, performanace and reliability. Most would be easily reversed and I have the original parts squirreled away, just in case.

Cheers!

Alan
 
In the summer I live at 7,000' about 10 miles north of Tucson, so my drives often end up in 100+ heat followed by a 5,000' climb up a mountain road. Pretty good work-out for a cooling system. Here are things 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 even 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 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 ( piece of broomstick jammed in the hose) for 20 years w/o such problems.

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).

There are 2 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) Other thing is an up-graded water pump I have heard about but not pursued.

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

I suspect you've got some rusty gunky build-up somewhere as even a TR w/o all these mods should be able to maintain a normal temp at road speed... most of the changes I have made are for uphill, slow traffic and/or 100+ degree days.
 
When we first started working on my little beastie, my mechanic noted how nice and clean the motor was on the inside. The rocker arms had no gunk built up on them and the cylinder heads were clean of carbon.

Here is my theory: When the front end collision happened, the owner figured that it might be a good time to rebuild the engine. When it all got back together, with the TR3a nose, no one figured to set up air baffles for the radiator. There was an overheating problem, so the thermostat was removed and the car wasn't driven much.

I have a neighbor who knew the original owner. The original owner had been a pilot who had eventually gotten into touring motorcycles and died in a motorcycle accident, leaving the car to his son who didn't drive a stickshift (idiot! learn a new skill!). The son sold it to a club member who really wanted an Austin Healey, who sold it to me.

I am going to talk to my neighbor to see if he can confirm any of my theory.

Thanks again to everyone.
Glenn
 
And keep in mind that the fibreboard shroud was painted the same color as the body (not left natural tan like the TR3A on the cover of the new Moss catalog).

I know you're not necessarily concerned with having an original car but this is an easy thing to do right and it really does look better in body color.
 
To check a tr3/4 for a clogged up block, open the draincock under the manifolds. Nothing comes out??? now unscrew the petcock completely. Still nothing?? clogged block syndrome, not pretty but it happens.If you have this problem you will be dogged by heating problems forever.
MD(mad dog)
 
Back
Top