GT6 thermostats

[rotoflex]

Is there supposed to be a little hole in the deck of the GT6 thermostat for bypass?

I cannot recall if the GT6 thermostat is supposed to have a little hole in the deck for bypass or not.  Maybe I'm thinking of something else, like a Jaguar XK engine.

And I can't remember if it's the GT6 that's not supposed to be run without a thermostat because of the coolant circuit design.

[drofgum]

Bill,
I'm not sure about the GT6, but most thermostats have the small hole to allow a pilot flow even when the thermostat hasn't opened.
Most cooling systems will be woefuly inefficient without the thermostat. The restriction to flow causes pressure to be maintained in some spots which otherwise would be subject to cavitation. The cavitation in turn leads to blanketing of parts of the surfaces to be cooled by steam bubbles which don't conduct heat nearly as well as  flowing water. Compounding this is the fact that the water pump impellor is especially prone to cavitation which disrupts the flow through the system.
                                                                       All the best,
                                                                       Paul

[hymodyne]

I've been wrestling with overheating issues  since I first started the car after the rebuild. I took off the thermostat to eliminate its failure from the causes of the high temps; should I get another and put it back in?



I installed the block above the rad in an effort to force air to go through and not past the rad.
Still no test runs with temp below "H"

Suggestions appreciated.

James

[mikeyb]

are you certain the car is truely running hot?  You could have a faulty/mismatched gauge/sender unit

[piman]

Hello James,

yes, it's not a good idea to run without a thermostat.
The first thing is to confirm that your temperature gauge is not reading high, or does it eventually boil? If the block waterways are clean and the water pump is in good condition, the only thing left and, often the most common culprit, is the radiator? Yours look new so I assume it is clear but is it large enough? Having said that, the air intake looks quite small?

Alec

[hymodyne]

I will install a new thermostat and see if it makes a difference. small intake, yes, with the plate required up front, but

would that make such a difference?

James

[Tim Bancroft]

Do check as Mike B states. I had what I thought were hot running issues years ago with my mk2. Changed the temp gauge for a mechanical unit and found that the car was in fact running ok. I had changed the voltage regulator, however in the end reckon that resistance in the wiring loom was causing a problem. All 3 of my Triumph cars now run with Smiths mechanical temp gauges, accurate enough for these old cars.

I still believe that a std GT6 will cope with the std radiator, ensure that the whole cooling system is in good condition and duct the air through the grille and all should be ok.

Its only us poor misguided fools with mod'ed cars that have problems!

[ferny]

timbancroft61 wrote:

Its only us poor misguided fools with mod'ed cars that have problems!

Indeed. One mod normally necessitates another. It's a never ending vicious cycle.  :B

[Mr Elsie]

I've just ran mine without a thermostat for a couple of days as I've some had overheating issues. Ended up swapping the rad cap from a 7 to 13 and all looks ok now. Will be putting a new thermostat in when it arrives plus doing further flushes and removing the sump bolt to check for gunk etc.

[gt6878e]

I've just took the thermostat out of mine to see if it would help the car run cooler. So does everyone rekon i should get a new one in?

Thanks

Darren

[Richard B]

2572 wrote:

I installed the block above the rad in an effort to force air to go through and not past the rad.

Nice radiator, however I would still fit shrouds to the sides and top to stop air going around it instead of through it.

[piman]

Hello James,

if you have a real overheating problem, not a pessimistic gauge, the replacing the thermostat will not cure it. It will ensure better real cooling inside the engine as the water flow is controlled as it should be. Racing cars often fit a restrictor plate instead of a thermostat.
Will a small intake affect things, it can, Jaguar in the fifties streamlined their 'C' type by fitting a longer nose with a smaller intake; all their cars retired with overheating.

Alec

[hymodyne]

Richard_B wrote:

Nice radiator, however I would still fit shrouds to the sides and top to stop air going around it instead of through it.

[smithy]

Yum yum Ram Air filters.

[Paudman]

Strange angle for a rad; I'd be concerned air is flowing up along the front of it rather than through it. As Richard says, get some form of shroud round it to force air through.

[Richard B]

I can see side 'shrouds' attached to the bonnet but do they seal against the sides of the radiator?  :-/

[Richard B]

s

[heraldcoupe]

Is it a quirky angle to the photograph, or is that filler cap on the side of the radiator?

The way the radiator's angled goes against my gut feeling for how the air flows through the engine compartment, but I've not studied the subject in detail - what's the current thinking that leads to this approach?
Is there a fan on the back of that - presumably that's what the fixing lugs on the top face are for? If so, does it suck or blow?

Cheers,
Bill.

EDIT:
Is that radiator actually mounted at at a 90 degree angle to it's intended position?

[hymodyne]

It is canted at a rearward angle. there is a 10" puller behind it, along with the fan on the crank.

Took it out for a drive this morning and still had major heat issues, so I pulled that rad and replaced it with my stock one, although I had to mount it sideways due to the oil cooler in its lower space between the frame rails. Just got back from a drive with this configuration, heated up even hotter and faster than the aluminum rad did.

James

[heraldcoupe]

These radiators aren't designed to work mounted sideways. As a simple finger in the air estimate, I reckon you're only flowing water through about 1/3 of the potential working area by making the water flow sideways, rather than allowing the vertical flow intended by design.

I also feel that your puller fan is counter productive. The angle of the radiator means it's trying to force warm air downwards, against convection currents. Given that the fan is going to be most use when the car is slow moving or stationary, ie air isn't being forced through by the forward motion of the car, all your fan will do is fight against the natural convection current. If the radiator was tilted forwards, your arrangement would be more logical,

Cheers,
Bill.

[ferny]

Won't water syphon when the radiator cap opens as well?

[nang]

With the radiator on that angle and the blanking piece on the top, is the hot air behind the radiator being restricted from escaping ?
Tony.

[rotoflex]

I also think it needs shrouding.  At that angle, air is blowing over & under it.  On the upright radiators without shrouds, they at least stand in the way of some airflow.

[junkuser]

How do you make sure the system is actually full of coolant James?
There does not seem to be a filler or bleed at the highest point in the system.
Are you sure there is no air trapped in the upper part of the system preventing circulation?
The circulation is assisted thermosyphon by design, the pump is to assist but the thermosyphon is still an important part, especially after shut down and trapped air could stop this if down to a sufficient level.

Just a thought.

[hymodyne]

junkuser wrote:

How do you make sure the system is actually full of coolant James?
There does not seem to be a filler or bleed at the highest point in the system.
Are you sure there is no air trapped in the upper part of the system preventing circulation?
The circulation is assisted thermosyphon by design, the pump is to assist but the thermosyphon is still an important part, especially after shut down and trapped air could stop this if down to a sufficient level.

Just a thought.

I'm installing a bleeder in one of the lines coming from the expansion tank (mounted on the firewall shelf) at the highest point on the engine in the next few days.

James