MG TD TF 1500 Temperature Gauge Sensor Relocation BBS discussion at MG-Cars.info

MG TD TF 1500 - Temperature Gauge Sensor Relocation

Hi, I recently modified a MG TD water outlet to install a gauge sensor port for the mechanical temperature gauge. After searching the BBS Archive, I found temperature sensor relocation information in several posts that contained accurate information for our TD (David DuBois for example); and several posts with information that was helpful, but less accurate. The conflicting information can be confusing at best when you are learning. So I am posting this only as an update for anyone doing a similar search of the archives in the hope they might find the information useful. Most of you probably know this information. Newbies like myself might not. In the spirit of helping, please let me know if my information also needs updating/correction. Mechanical temperature gauge ports are traditionally 5/8-18 threads and the temperature sensor seats/seals against a machined shoulder and not the threads. The 5/8-18 male threads are 0.625-inches outside diameter. Our TD has a 5/8-18 adapter port installed in the radiator tank at the factory. Picture 1 and 2 A 3200-06-06 3/8 NPT male fitting also has 18 threads per inch with an outside diameter of 0.675-inches. NPT fittings are designed to seal against the threads. A 9522-06 3/8 BSPP male fitting has 19 threads per inch with an outside diameter of 0.652-inches The male connector has straight threads and an o-ring that seals against a flat external surface on BSPP female ports. Picture 3 Unfortunately (depending on your viewpoint), a 5/8-18 temperature sensor will thread into 3/8 NPT and BSPP female adapter fittings, although both will have a definite looseness until seated. Both can be made to seal in a low pressure cooling system like the TD. However, neither are correct IMO and 3/8 NPT or BSPP plugs will not fit into the TD radiator sensor port to seal the radiator after you relocate the sensor. Auto Meter and other companies make a number of 5/8-18 mechanical gauge temperature port fittings and adapters that work with a TD temperature sensor. And, they can be purchased at a fair price with whatever male threading you want. One example with the correct length for a TD sensor is shown below. Picture 4

WHTroyer

3/8 female BSPP fittings are a close match to the sensor port.

WHTroyer

Example of an Auto Meter mechanical temperature gauge sensor port with the correct 5/8-18 threads and offset.

WHTroyer

Sorry, grabbed the wrong picture and it was too late to delete.

WHTroyer

I think there are two different type fittings at the end of the capillary tube, male and female. Mine looks like this and I was able to attach it to a pipe nipple fitted to the thermo housing elbow.

John Quilter

Hi John, that's a good point. It is my understanding the two different fittings are for the TD and TC. The TC fitting has a cap as you show and I believe it was also used from the factory on early TDs. More knowledgeable people will know the years and hopefully comment. Regards, Bill

WHTroyer

This thread was discussed on 20/12/2016

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