TR2/3/3A Still Overheating ...

[mgedit]

Have removed original bellows thermostat and tested. Seems to work fine in pot of water. Also readjusted timing. Still getting temperature issues. Runs great for 3-4 miles and then slowly creeps up. Wondering if thermostat is not opening when in car. One possibility is to remove thermostat entirely and see what happens. If I try this does bypass need to be partly blocked? Could also try modern thermostat. Any cross reference as far as part numbers? What is best way to partially block bypass? Any other suggestions or ideas most welcome. Cheers, Mike

 

[CJD]

If the thermostat checks out in hot water, I really doubt that is your problem. What is the history on the radiator? The tubes could be blocked with scale or stop leak from a PO. Also, are the hoses on the suction side firm enough to ensure they are not collapsing at speed? It seems like I remember you saying this is happening at speed, rather than at idle. How does it act for extended idle?

 

[Geo Hahn]

You should be able to tell when the thermostat opens by (carefully) feeling the top radiator hose. I will get somewhat warm as the engine gets hot, but then will quickly become hot once the thermostat opens. But it does not sound like the thermostat is the problem.

If you have an IR thermometer you can check the temperatures at the top and bottom of the radiator -- the difference will give you some idea how effective the radiator is. They can perform poorly without actually leaking. I'm guessing here -- but I think you want to see about a 20° drop top to bottom.

While the thermometer is out is also the time to verify that the gauge is telling you the truth (if you haven't done so already). I painted a patch of flat black paint on the thermostat housing (as that is also where the temps sender is) to give me a reliable target for the IR thermometer. I also put one of those LCD temperature strips on the housing.

If you do block the bypass hose (and there is no need unless you go to a modern thermostat) -- I used a 3/4" copper cap with a 3/16" hole drilled in it:

That by no means exhausts the possible things to check, but it is where I would look next.

 

[LarryK]

How old is the waterpump? Vanes could be worn as the metal does wear pushing water.

 

[mgedit]

Thanks for the suggestions. Will keep investigating and report back. Hoses are new, not certain of the age of waterpump. Rad came with car and was supposed to have been refurbished. Cheers, Mike

 

[Don Elliott]

On the subject of water pumps, I'm still using the brass or bronze 4-vane impeller that came with my 1958 TR3A when I bought it brand new. When I replaced the seals on the pump in 1990, I had my neighbour turn a new shaft out of stainless but recently, the seal leaked after another 110,000 miles. When the seal leaks the coolant level drops and you find water stains down the front of the engine below the pump.

The impeller in the repro pumps with 4 vanes is made of cast iron - that's why I stayed with the brass impeller. Also the impellers on the repro pumps are smaller on the outside diameter so they pump less coolant because the flow goes around the ends of the vanes instead of out the pump.

Do you want a ride Saturday with me ?

 

[TR3driver]

FWIW, I have twice now had overheating problems that turned out to be a defective "refurbished" radiator. The last time around, the radiator shop reported that it was "fine" several times; until I insisted that they "rod it out". Once they tried to rod it out, they discovered that every tube was coated with what they called "mud" (highly technical term there) until they could not force the rods through! This was a radiator that had been recored in the past and was working fine in my previous TR3A before it got wrecked some years earlier.

The one before that was not blocked at all (they did rod it out) but apparently the fins were not in good thermal contact with the tubes. It was the original style where the tubes are just forced through the fins (rather than soldered) and evidently there was corrosion or dirt inside the joints.

There are lots of aftermarket thermostats that will fit. I use a Robertshaw 330-180, which is a "balanced flow" type. Unfortunately, it seems that they quit selling those and I don't know the application information offhand. Measure the outside diameter of the mounting flange and ask your FLAPS to match that.

Personally, I've never been able to tell the difference with the bypass open or partially blocked. Even fully blocked (with a hole drilled in the thermostat so there is always some circulation) did not help with my overheating issues. Then once I had the bad radiators recored I had no problems leaving the bypass fully open. It's worth noting that even the factory eventually dropped the sleeved thermostats (although the bypass passage was a bit smaller on the later thermostat housings).

I also tried three different flavors of water pump, with no discernible effect. Here's a comparison, where you can see the differences Don is talking about. Note that the aftermarket pump on the right had well over 100,000 miles on it when this photo was taken and was still working fine. I ultimately put it back on the engine, simply because it had worked well for so many years and the others didn't seem to make any difference. Unfortunately it started to leak a few years afterwards, so it has since been replaced with a new pump & pulley from TRF.


More comparison at https://s258.photobucket.com/user/TR3driver/library/TR3-4 Water Pumps

 

[mgedit]

Thanks for the extra information re pumps. Just ran up to temperature at idle and it sat at 185 for about 5-6 minutes. Bypass got warm quickly. When idling, top hose (it is one of the ones with fabric covering so some insulation effect maybe) was warm but I would not call it hot. Thermostat housing was hot. The bottom hose took some time to warm up too and near end of idle period it was hot (while top was warm) based on my hand but no fancy IR thermometer. When I shut off engine temperature climbed a little (see pic), which I think is normal.



Don I need to work gate at 8 so have to leave here early. Still hope to drive in the 3 but (fortunately for show) it is supposed to be 28 and sunny Saturday so that won't help any overheating issues I might still be having.

Cheers, Mike

 

[GerryL]

Had encountered an overheating problem wheere a non bypass thermostat would only partially open. Is it possible that your thermostat is not opening completely?

 

[sp53]

If I had a known good radiator and a fan upgrade and water was not coming out the overflow, I would suspect the gauge.

 

[Geo Hahn]

Certainly a good idea to verify the gauge but in my limited experience the cap tube gauges (if they are still working) usually hold their accuracy whereas the electric gauges are prone to a variety of errors.

 

[pdplot]

What about an airlock in the cooling system? I've seen that happen after draining and reflushing the radiator in a couple of different cars through the years. Just a thought. Your gauge may be off too as someone said. You don't want to drive around with water boiling in the system, for sure. Check your timing again. Make sure it advances when you open the throttle. Use a timing light and mark your pulley with a piece of chalk. These things can be maddening, but what the **** - you could be driving a boringly reliable modern car. Besides, if you didn't have an LBC, what would you do for aggravation - play golf?

 

[martx-5]

Certainly a good idea to verify the gauge but in my limited experience the cap tube gauges (if they are still working) usually hold their accuracy whereas the electric gauges are prone to a variety of errors.

I agree that generally either they work or they don't. However I had one capillary gauge on my TR3 that was slowly, over about a one week period, losing it's ether and the reading kept getting lower and lower until it didn't read at all. I really don't think it can fail the other way.

 

[mgedit]

Thanks for the additional suggestions ... I have two Triumphs (both acting up) and I play golf as well. Have more than enough aggrevation in my life just now for sure

Cheers, Mike

 

[TR3driver]

Certainly a good idea to verify the gauge but in my limited experience the cap tube gauges (if they are still working) usually hold their accuracy whereas the electric gauges are prone to a variety of errors.

Oddly enough, I've had the opposite experience. Of the "capillary" tube gauges that I've had, probably half of the ones that worked at all were quite inaccurate. The element that flexes as the pressure changes (they are basically Bourdon tube pressure gauges) is brass and IMO inevitably work hardens and distorts with age. I've seen them read too high across the scale, too low across the scale, or even too high at low temps and too low at high temps. I've also seen more than one ruined by a single bout of overheating, even when there was no other damage.

At least the electric ones can easily be calibrated. But the early TR4 temp gauge I got from Fred Thomas was right on the money (though it's possible that he calibrated it before selling it to me).

 

[TR3driver]

I really don't think it can fail the other way.

There's one in my parts bin somewhere that reads about 1/4 scale even while in the bin ... it will move upwards if you get it hot, so it still "works", but it reads drastically high.

 

[Don Elliott]

Mike - It was great to see you yesterday at Britannia Bay. You TR3 looks super.

Have you considered running it with 100 water to see what happens ?

Have you considered "Water Wetter" ? Just "GOOGLE" it.

Cheers - Don

 

[TFB]

Mike - It was great to see you yesterday at Britannia Bay. You TR3 looks super.

Have you considered running it with 100 water to see what happens ?

Have you considered "Water Wetter" ? Just "GOOGLE" it.

Cheers - Don

I would think most likely the radiator,especially if over ten years old.If I had a sound engine and old radiator I would think its a lot cheaper to replace radiator than do a premature rebuild from overheating problems.
My rebuilt engine with new alum radiator rarely gets hot enough to turn on the elec fan if car is moving,no mechanical fan,original bellows type stat and stock bypass .
Tom

 

[Geo Hahn]

...While the thermometer is out is also the time to verify that the gauge is telling you the truth (if you haven't done so already). I painted a patch of flat black paint on the thermostat housing (as that is also where the temps sender is) to give me a reliable target for the IR thermometer. I also put one of those LCD temperature strips on the housing...

As a follow-up, here is a pic of that flat black dot and the temperature strip:

IR thermometers are so cheap & very handy I would not be without one. The LCD temp strip is possibly overkill but entertaining & quick to check (and quite accurate). The LCD is available on ebay, Amazon, etc.

 

[TR3driver]

As a follow-up, here is a pic of that flat black dot and the temperature strip:

In case it's not clear, the purpose of the black dot is so the IR thermometer can take a reasonably accurate reading. When trying to shoot the bare aluminum, I can get 25 degrees change in the reading, just by moving the dot a little bit!

The problem is that the IR thermometer relies on a property called emissivity (basically how brightly the surface glows in infrared) and the emissivity of aluminum varies all over the place. If you are interested, you can read more here https://www.omega.com/prodinfo/infraredthermometer.html (but most cheap IR thermometers have no adjustment for surface emissivity).