Herald Temp gauge fitting

[Tom]

Hello, I have acquired a Smiths  TC4303/08 Temp gauge which I believe might be a temp gauge for a 1200 Herald?

My 1965 Herald doesn’t have a gauge and I’d like to fit it if possible? My main question is what type of sender do I need and do I need a voltage stabiliser?

[Josef]

I think that number might be for a Spitfire gauge. If so you’d need the GTR108 sender, and yes you do need a voltage stabiliser. But I’d guess you should already have one fitted for the fuel gauge?

[Tom]

Thanks for the response, I’ve had the gauge years, can’t remember where I got it? Ive Also got this sender, it doesn’t have any markings on it, the insulation on it is black, I’ve read this might be an identifier?

I’m also in the process of aquiring an water pump housing with a threaded inlet to screw a sender into. I also have a thermostat housing that this screws into but I think it would foul the thermostat hence the need for a new wp housing or maybe I could aquire an adapter to raise the sensor?

[Josef]

My Mk3 Spitfire (7psi rad cap) and 13/60 (13psi rad cap) do have different coloured insulation. Red for the 7psi and black for the 13psi. However my spare for the 13/60 has no colouring there! (And I’m surprised Canley’s only list one sender for the Mk3 as I’m pretty sure two different ones were used when the cooling system pressure was increased?)

Interestingly though the spare one is shorter than your pictured one. Presumably you would need one of these shorter sender to fit in the thermostat housing you have.

[Pete Lewis]

there are only two senders

slow moving needle bi metal stabilised gauges use GTR108

non stabilised , waggy needle non stabilised use 121997

take care that the sender in the top of the thermostat hsg does not reduce the stat opening

and its measuring stat output rather than engine input temperatures 

Pete

[Peter Truman]

I recently replaced the Vitesse's original sender with a locally supplied Tridon unit listed as a GTR108 replacement, absolutely useless as it only just gets off zero rather than the originals 1/2 range. Usual aftermarket rubbish!
 

 

 

 

 

 

 

 

[Colin Lindsay]

The choice is to either fit it in the cap, or the housing; if you have a drilled housing then using the original sender won't (or shouldn't) hit anything inside although this depends on the actual thermostat - there are bound to be modern versions that differ slightly from the originals so check the top profile and fit the flattest you have. There's plenty of room above in the Herald engine bay so it shouldn't hit anything. 

If anyone else has a housing with the two blanking plugs on the side these will unscrew easily enough so you can fit the sensor in the same way as the later 13/60 did.

The sensors are supposed to be marked red or black depending on whether they're non-stabilised or stabilised; part numbers are GTR108 with alternatives of DAC2583, 568055, C40106, C40106A, C34812, FAE31210, or TT4803-00A. Stabilised are black but you'll often find green as well as red non-stabilised, and many suppliers have nothing but black for either fitment, just to confuse things... so best thing is to find original NOS stock and you're sure it's good and not repro. Plenty of them still about!

[johny]

I thought that hole in the thermostat housing was for a brass vent plug. If you put the temperature sensor in there it will not be a good measure of engine temperature before the thermostat opens while the proper hole in the water pump casing will show the temperature more accurately as the engine warms up (useful for choke operation?)....

[DanMi]

1 hour ago, johny said:

I thought that hole in the thermostat housing was for a brass vent plug. If you put the temperature sensor in there it will not be a good measure of engine temperature before the thermostat opens while the proper hole in the water pump casing will show the temperature more accurately as the engine warms up (useful for choke operation?)....

Early cars did have the temperature sensor after the thermostat, which is not ideal

I think the looking at the colour isn't accurate as they have been made over the years by various companies as replacements who will likely have used different colours.

[Colin Lindsay]

1 hour ago, johny said:

I thought that hole in the thermostat housing was for a brass vent plug. If you put the temperature sensor in there it will not be a good measure of engine temperature before the thermostat opens while the proper hole in the water pump casing will show the temperature more accurately as the engine warms up (useful for choke operation?)....

Don't forget, early Heralds never had a gauge, so it was probably more an indication of how the engine was performing as it drove along, fully warm, rather than any notion of fuel saving at the choke end...

[johny]

29 minutes ago, DanMi said:

Early cars did have the temperature sensor after the thermostat, which is not ideal

It seems though, as Tom has a choice, it would be better for him to install the sensor in the water pump housing rather the thermostat cover. Would this have been the set up on a 1965 model fitted with a temperature gauge?

[DanMi]

16 minutes ago, johny said:

It seems though, as Tom has a choice, it would be better for him to install the sensor in the water pump housing rather the thermostat cover. Would this have been the set up on a 1965 model fitted with a temperature gauge?

totally agree, the spitfire moved the sender to the housing somewhere in the MK2 run but earlier than my Aug 66 so probably at some point in 65

[Colin Lindsay]

2 hours ago, johny said:

It seems though, as Tom has a choice, it would be better for him to install the sensor in the water pump housing rather the thermostat cover. Would this have been the set up on a 1965 model fitted with a temperature gauge?

Heralds didn't get them as standard until 1967 when the 13/60 came out, but in previous models where it was added as a special item, eg the Coupe, they were fitted to the cap - I could assume that when requested by a customer they would be fitted by the dealership? It's interesting that the waterpump housing for early Heralds had no capped drillings, but they appeared later in production and I suspect in conjunction with the other cars that used the same housing eg Spitfire. The early Vitesse used a slightly different arrangement on the housing. For a 1965 model it probably depends on the commission number / exact date of manufacture to determine which it would have had.

[Josef]

Interesting that there is only one sender, the Thomason Spitfire originality guide says it was changed when the cooling system pressure was changed ‘in order to retain the same gauge’. But thinking about that it doesn’t actually make any sense. Higher pressure will increase the boiling point of the coolant, but it’s not going to change the normal operation temperature of the engine. 

[Tom]

Yes I potentially do have a choice if I manage ti get this water pump housing withe the threaded area for the sender. I agree the best place for it is before the thermostat.

I had a play with the gauge and sender tonight, I borrowed a power supply from work, set it to 10v and wired it to the sender I have with the black insulation. I popped it in a mug and poured in boiling water, the gauge moved to somewhere between normal and hot which must be roughly correct?

[Peter Truman]

The daughters 66 Mk2 has the temp gauge fitted into the water pump/thermostat housing as standard, but I fitted the electric fan auto switch into the thermostat  cover by using the rare cover with a thicker area and tapping thro that.

My argument was that the fan won't switch on until after the thermostat is fully open anyway, so being above the thermostat wasn't an issue.

[Tom]

Reading your comment Peter it looks like I have a third option as I think I may have thermostat housing with the thick bit? No idea it is rare?

[Colin Lindsay]

If it's the same as this one it can be drilled out:

  

[Peter Truman]

I drilled mine out and tapped it, but can't remember if  3/8 NPT (18TPI), or 3/8 BSP (19TPI), to fit the sender thread, but not metric but be careful as there is NOT a lot of meat there and if out of alignment it'll be easy to cut into the bolt hole!

When ever I have the opportunity to obtain the special thermo cover in reasonable condition I do just in case I want to do a later mod, so I have a couple in case an alternative thread is reqd as there's definately no room to fit a thread changing bush..

[Colin Lindsay]

9 hours ago, Peter Truman said:

When ever I have the opportunity to obtain the special thermo cover in reasonable condition I do just in case I want to do a later mod, so I have a couple in case an alternative thread is reqd as there's definately no room to fit a thread changing bush..

So THAT's where they all are. Last one I fitted, I just cheated and used a later waterpump housing from a 1200, and unscrewed one of the blanks. It's already tapped for the correct thread.

[PeteH]

This is O/E (13/60) as far as I am aware.?

I assume it is Below the Thermostat?.

Pete

[Colin Lindsay]

2 hours ago, PeteH said:

This is O/E (13/60) as far as I am aware.?

I assume it is Below the Thermostat?.

Pete

Yes, it's below. The pipe to the right is the under manifold pipe on the 13/60 so there's a good flow in that general area. 

Early 1200s didn't have any take-offs at all, but later models had two blanked off, yet the gauge sensor was still placed in the thermostat housing.

  

[Peter Truman]

Yes but Colin I needed 3 tappings/outlets one each, for the manifold hose, temp sender and one for the elect fan cut in switch, hence the use of the rarer thermostat cover!

[Jon J 1250]

Just to add to the timeline, my mid 1965 built 12/50 was built with this water pump with one blanked off port (which I intend to use for a capillary type sender) and a thermostat housing with a blanked off port on top.

[Tom]

Yes mine that type but I’ve potentially got the opportunity for a later pump housing with tap off so I’m waiting to here back, this would be my preferred option I think. Strange how there were so many variations in such a short amount of time? I find it unbelievable Triumph sold a car with absolutely no indication it was overheating and about to seize up???