Thermostat Opening

[bigmalcy]

Hi folks

So today I took the old girl for a drive to test the cooling system and overdrive and she went beautifully, but unfortunately she is still overheating when running at steady higher speeds (50mph +).  The needle just creeps up very slowly above the usual spot in the middle of the gauge and shows no signs of stopping, without pulling over of course.  On all other roads, where speeds are variable, the cooling system keeps up just fine.  There are now no signs at all of coolant leaks.  

It seems to me that there isn't enough flow through the system to get rid of the heat generated at higher continuous speeds / engine loads.  

So - tonight I took out the thermostat to see how it looked, and how it opened.  I don't have a thermometer, so wasn't able to measure the temperature at which it opens, but I did at least get to see it opening when placed in boiling water.  

The question in my mind is now whether or not the thermostat is opening 'fully'.  From the photos attached, does this look like it is 'fully' open?

If it is fully open, then I presume the other causes could be partially blocked radiator or water pump not performing... given the blockages I had before in the heater circuit and bypass hose, I suppose some blockages in the radiator would not be much of a surprise. 

I will probably fit a new hi flow thermostat and re-test, anyway, but interested to know if the existing thermostat is doing what it should be doing, and what your thoughts are more broadly.

TIA

Malcolm

[Lebro]

Hi Malcolm.

1st thought is do you have the "cardboard" ducting to direct air from the grill into the rad. without that overheating is common.

Also, when was the radiator last flushed through. they do get clogged up & so have reduced cooling effect.

Bob

[Z320]

Hi Malcom,

THIS is fully open,

on my tests this was at about +10 Kelvin over starting opening temperature 

Ciao, Marco 

[Andy Moltu]

Have you reduced the bi-pass hose.

The shroud on the bellows thermostat covers the opening to the bi-pass hose as it opens forcing flow through the radiator.

The “modern” stats like your picture doesn’t and, unless you put a reducer to limit flow in the bi-pass too much of the flow goes straight round without being cooled. Later cars had a modified housing with a reduced diameter hole where the bi-pass hose attaches.

If the bi-pass has been addressed you either have insufficient cooling from a furred up rad or failing water pump (occasionally impeller slip on the shaft or impellors corroded away but unlikely)

Or you are producing too much heat - lean mixture or retarded ignition. 

If losing water consider head gasket blowing.

[Hamish]

Malc as you are in Oz what temps are you enjoying !

my car fluctuates between the mid 185 and the next mark which is I think about 207f (where my elec fan cuts in) which is 85 to 97c  so still not boiling even without factoring in the pressure (4 to 7 psi) which will raise the boiling point .

But always worth flushing if not done for awhile. 
and don’t forget bobs point about the card or sometimes retrofitted ali duct in the front apron is part of the original design

Edited March 22 by Hamish

[BlueTR3A-5EKT]

As you are in Oz     Go and get one of these and fit it.   https://www.tridon.com.au/products/Tridon/35/479/thermostats-and-gaskets/528046/thermostat-high-flow
 

The 82 degree one I have in my car works just right.

[Z320]

Hi Malcolm,

my advice is not to improve anything that covers your problems - if you indeed have one?

About the opening of any thermostat:

for example a 86°C thermostat starts to open at about 86°C with a only very narrow gap.

This is often enough up to 20-25°C outside temp. because our TRs have a cold engine and a powerfull cooling system.

To open the thermostat more a higher coolant temperature is needed, this is the power for it to work.

My experiments with different thermostats showed they have been fully open at +10 Kelvin more (86° + 10 K = 96°C).

Means: you can't expect a temperature gauge pinned at 86°C with a 86°C thermostat under heavy load and +25°C outside.

This is only on our modern cars the case because they run hotter (more powerfull) and the electronic does this

to protect the producers from owner's worries like "if I do this the temperature gauge does that".

Ciao, Marco

 

 

Edited March 23 by Z320

[bigmalcy]

Hi fellas

Thanks for the input. 

Hamish - I get worried if the needle goes past the 185 mark, simply because under normal circumstances, even in hot weather and traffic, it never really spends any time up there, before the very effective Kenlowe fan kicks in.  It's interesting that yours spends so much time hotter... makes me feel better!  

I don't have the cardboard duct, but I do have the bypass restricted.  The duct didn't really seem to make much of a difference in my case: at least when I removed it, I noticed no appreciable rise in temps.  Timing hasn't changed to the best of my knowledge, so I really do think that the issue I have (car running hotter than ever before) is due to crud in the rad.

Marco - I understand the comment 'don't improve anything which masks another problem' (i.e. increase flow through the 'stat may mask a clogged radiator).  I'll take that advice and try to get the car back to its previous temps with the existing stat.  After I've achieved that (hopefully with a reverse flush of the rad), I will fit the hi flow stat recommended by Richard and others.

As for whether or not I do have an issue - the simple fact is that the car has started running significantly hotter than it did for the previous 9 years.  Something's definitely changed for the worse... I'm hoping that a reverse flush of the rad will do the trick.

So - is reverse flushing the rad as simple as connecting a hose to the bottom of the rad and blowing it out through the filler neck or top connection? The bottom of my rad just has a bolt plug... no valve, but I do have some spare block drain valves in a box.  Will these valves also fit the rad to make it easier to connect a hose securely?

 

Thanks again for the input fellas.

 

[Lebro]

The duct can make a big difference my friend has a 3A, and following an engine rebuild it would always boil after a fairly fast run. we fitted the duct, & no more problems.

Bob

[MilesA]

Like many 3A owners I had overheating problems which I eventually resolved as follows:

- Installed the cardboard duct

- Restricted the bypass

- Installed the high flow thermostat that Peter referenced

- Crimped the bars on the repro grille to increase the airflow to the radiator.

Each of these made an incremental improvement and collectively solved my over heating.

A PO had removed the mechanical fan and installed an electric fan. I also played around with different thermo switches for activating the fan and eventually used a non-standard temperature range switch which better suited my engine conditions. I also installed an override switch for completeness.

I also bought a cheap Chinese electronic thermal measure device which I plumbed into the top hose temporarily to measure more accurately the temperature when the thermostat and fan were kicking in by comparison with the car's temp gauge. Not essential by any means but helped me choose the best thermo switch.

Miles

[bigmalcy]

Hi fellas - trust me... this car's cooling was spot on for years... with standard stat, bypass restrictor and with or without cardboard thingo...  until some clod neglected her for too long and she decided enough was enough.

I found this post interesting... seems to match my initial experience perfectly (water loss but no obvious leaks from anywhere and reduced cooling performance).  Particularly the last comment from Vivdownunder... 

On rare occasions the engine releases rust particles that clog the top of the tubes. The top tank then banks up and forces coolant past the radiator cap. A backflush usually clears the debris.

 

 

[John McCormack]

I'm in Sydney and my cars only get to 185 in heavy traffic. On the road they don't get much above 165 even on 35degC + days.

I have aa TR2 and TR3 so have the ducting from the apron. I also use a Tridon thermostat recommended above with a restrictor in the bypass in the TR3 and a skirted thermostat in the TR2.

The TR2 has an electric fan manually operated and I rarely turn it on, even in the traffic I experience living close to the city in the inner west. The TR3 has a 6 bladed Triumph 2000 metal fan, they are great if you can get one.

It appears there is either a blockage in your cooling system, the bypass isn't restricted with a non-skirted thermostat or there is some other issue.

There are a lot of TR Register Australia members in Melbourne who would be able to give you a hand.

Edited March 25 by John McCormack

[bigmalcy]

On 3/25/2024 at 7:17 PM, John McCormack said:

I'm in Sydney and my cars only get to 185 in heavy traffic. On the road they don't get much above 165 even on 35degC + days.

I have aa TR2 and TR3 so have the ducting from the apron. I also use a Tridon thermostat recommended above with a restrictor in the bypass in the TR3 and a skirted thermostat in the TR2.

The TR2 has an electric fan manually operated and I rarely turn it on, even in the traffic I experience living close to the city in the inner west. The TR3 has a 6 bladed Triumph 2000 metal fan, they are great if you can get one.

It appears there is either a blockage in your cooling system, the bypass isn't restricted with a non-skirted thermostat or there is some other issue.

There are a lot of TR Register Australia members in Melbourne who would be able to give you a hand.

Hi John - agree there is a blockage somewhere, reducing the ability to get rid of heat.

I've just done yet another drain and flush with what I believe to be a stronger flushing agent than the first (big warnings not to leave it in for longer than an hour).  To flush the stuff out, I reverse flushed the rad (garden hose on the heater outlet hose), so hopefully that does the trick.  I won't know until I get her out on the freeway for a longer run at sustained speed.

Wish me luck!

PS - I had coffee with the Register members down here a few days back... a lot of good info from them.

 

[john.r.davies]

Have you an infrared 'gun'? Not pricey.   Scan that across the warmed up radiator ans look for blocked tubes that will be cooler.

John

[bigmalcy]

57 minutes ago, john.r.davies said:

Have you an infrared 'gun'? Not pricey.   Scan that across the warmed up radiator ans look for blocked tubes that will be cooler.

John

Hi John - good idea, and yes I do have one of those guns.  Have you done this yourself?

[john.r.davies]

Yes, some time ago, after using araldite to mend a leak

  I blocked the tube!