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MG MG Y Type - Y Type water temperature gauge

The april 2021 SF came today and I notice that Gerry Birkbeck has included a piece on fitting a temperature gauge to the interior of the car. I feel that this tells only half the story though Gerry as it leaves out the half under the bonnet. As someone who is contemolating this same job I would ask what people's opinions are as to where to put the sender unit and whether a mechanucal or electrical unit is favourwd. I am considering fitting an electrically operated unit as the wiring is easier to run than capilliary tubung. Is it feasable to fit the sender to thermostat housing or to an extra block fitted between the thermostat and either the block or elbow. I feel that there would be problems with either the top hose alignment or length with such solutions. Also can any sender be used with any gauge. Are these things standardised or is it possible to match them, perhaps with a resistor? How have others tackled this?
Thanks. Ian Thomson
ian thomson

Hi Ian,
I went for an electrical water temp gauge in both my YT and YA. As you can see I fitted the sender in the side of the elbow at the front of the head. There is enough material here as it is a non-pressurised system and fine thread on the senders, but you will need a suitable Taper Thread tap to fit the sender.

This is the ideal location to measure engine water temp - where the water exits the engine, just below the thermostat.

I run the wire through a piece of bundy tube on the side of the rocker cover, fixed to the "spare" boths on the cover. The bundy tube straps are made from metal pallet strapping.

From the back end of the bundy tube, I zip tied the sender wire to the oil pressure pipe through the firewall & to the gauge.

In the YT, the gauge sits below the dash to the right of the steering column, and on the saloon I mounted it inside the glovebox, so it's hidden when not in use.

Safety Fast

Tony Slattery
The Classic Workshop
Black Mountain Qld
Australia





A L SLATTERY

Hello Tony,
you probably had to convert your cars to negative earth, as these "modern" senders expect minus to the senders housing?

regards
Walter
Walter Prechsl

Surely not Walter. There can't be any active components in such old and simple technology which would make the sensor er, sensitive, to which way round it is connected. As far as I am aware they just contain a temperature sensitive resistor. The gauge may need reversing but this is easy enough surely with a wooden dashboard.
I like where you have put the sensor Tony and may copy it but am loath to drill holes un such parts. Do you really think that it will have taper threads?
Ian
ian thomson

Ian, here are 2 photos of my water temp guage in same position as Tony's.




Stuart Duncan

All my MG's are negative earth - from 1930 M-Type to 2004 ZR160 and 6 more in between. That way I don't need to remember which are NOT negative earth.

As far a drilling holes - it's just an elbow, plenty of spare ones around. All the senders I have are tapered thread, but with a little sealant a paralel tap should be fine.

Safety Fast

Tony
A L SLATTERY

Hi All,
We fitted this one more than forty years ago, still working ok. Th/housing is off for new top hose,( the rubber wall is approx 2mm thicker
on the old hose than the new one) Goodness knows how long its been on but now rather hard with no give.
John YB0362


JC Jebb

Thanks John. Did you install the sensor on the opposite side to the bypass hose take off? If so did you braze a boss to take the thread? I have been wondering if I could just tap out the existing boss but wondered if it would interfere with the thermostat. I don't really consider the bypass to be necessary nowadays unless an original type thermostat is in use (are any?) as it can be replaced by a hole drilled in the modern thermostat flange.
Ian
ian thomson

Dear all,
did anybody experienced the solution to install the sender unit in the upper hose going to the radiator ? I have a spare part which could fit ( image 1 ) and I would like to dismount the improvised plumbery solution ( image 2 ).
The black hose goes to the heater inside, so in summer either you drive in a sauna, or when you close the heater you don't have a correct temperature information as there is no water flow trough the hose.
Thanks for any feedback.
Maximilian & Y5671




Maximilian Burger

Hi,
pictures of sender unit fitment to thermostat housing, as you can see it's pretty robust as is
the sender unit not like the skinny ones of today.
, aah modern technowledge ?? but i have changed far more skinny ones than these big beasts. Not sure i would like to rely on just threadjng the castings without reinforcement. If you look at how far the modern cars sender units are screwed in to blocks etc and how much thread is on modern senders.Manufactures would not thread to the extent they do if they thought it was screwed into a few mm of casting.
John YB0362





JC Jebb

Just a picture of inside the th/housing with sender fitted.
John YB0362

JC Jebb

The elbows I have drilled for a modern sender have all been 3-4mm thick which usually means 3 or 4 full threads engaged - a little "Stag" on the threads and I have never had one move or leak water after 15 years and around 25,000 Miles. I've lost count of how many cars I've done like this over the years. Four of my own cars and probably even more for other owners.

I have the proper bypass thermostats in my cars, so putting the sender in the thermostat housing is simply not an option.

Safety Fast

Tony
The Classic Workshop


A L SLATTERY

Tony S. - reactivating, as I very much like your chosen modus, position of sender, etc. Being in Aus like you, can you recommend a particular brand, specs etc. of electrical sender/gauge that you have used? I'm thinking of tucking the gauge away in the glovebox. Thanks as usual. John.
J P Hall

Hi John,
I now prefer an Engine Guard to a temperature gauge in our old cars. We don't need an extra gauge to watch - need both eyes on the road.

Cheers

Tony
A L SLATTERY

Doesn't look bad, Tony - did you use the bolt-on option? Still at the elbow? I'm still positive earth, so will need to check polarity sensitivity. I'd consider also putting in the voltage indicator bit.
Thanks for your input.
John.
J P Hall

Yes, bolt at the head to elbow joint. That is the hottest part of the head and the first to heat up when you have a coolant failure.

Cheers

Tony
A L SLATTERY

I am pleased this thread has been resurrected as it was very remiss of me not to supply an update on what I had actually done to answer my own question. The attached photo illustrates my attempt based on the replies I got here. As you can see I fabricated an insert for the electrical sender unit which I may also use as a heater take off later. I pinched the conduit idea for the wiring from here also. Thanks. I was going to cut the top hose down to fit but so far it has fitted without modification. I have stayed with negative earth, simply connecting the gauge as it expects which is not a problem as the wood dash makes an admirable insulator from earth and it works fine. Tony, I don't know what an engine guard is, presumably it is a proprietary unit available in Aus. I am with you on not distracting the driver though so I prefer older technology without the myriad cockpit displays to amuse the driver.
Ian Thomson





ian thomson

Hi Ian
I like your idea for mounting the sensor .
I used a capilliary gauge purely because I had one .
I fitted the sensor in the same place as Tony fitted his and pinched his idea ( thanks Tony) for routing the tube back to the dash. I made a slotted tube because the sensor was too big to thread through the tube .
For the sensor I had a fitting for use when putting a sensor into a hose . I drilled the casting in the same place as Tony and made it a tight fit . Then i bonded it in using an epoxy metal recommended for marine use.
Just have to remember to feed everything through from inside the car . Added a bit of sealant around the collar of the bulb and so far so good .
Cheers John B YA 4424





J K Bowman

I agree with TS and the method of electrical connection.
However I wouldn’t put in the glove box, ( that’s for kid gloves , it needs to be seen.and to keep the eyes on the road..
I also installed a thermo fan so I won’t heat up on the Pentland hills to Ballarat .
Temp watch as important as oil watch., Ever seemed right to place the sensor on the bypass pipe as some do.


CR Dickinson

I have just returned from a 4 week tour of Southern England in a borrowed YA Saloon.

The car was fitted with a temperature gauge that never moved above 70 deg F.

I have taken with me an Engine Guard as a precaution. This took about 10 minutes to fit - attached to a bolt on the front of the head, and the display unit mounted in the drivers side ashtray.

As I suspected, the Engine Guard was able to give a real time reading on the cooling system operation. The poor car never got to proper operating temperature (except after a long highway run and after the engine was switched off) - I suspected the thermostat had been removed to cure another issue (likely a blocked rada=iator core).

I did manage to source a bypass thermostat to fit, but available time/workshop and the worry of the radiator condition, led me to "leave as I found", and we avoided motorway driving to keep a bit more heat in the engine.

Cheers

Tony
A L SLATTERY

This thread was discussed between 01/04/2021 and 15/06/2023

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