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TR2/3/3A TR3 Water Temp Sensor Installation Problem

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Not sure how someone could claim to have restored a temp gauge w/o having included a functioning capillary tube. Unlike the oil gauge, the line for the temp gauge is an integral part of the gauge as it is sealed and contains ether.

Some have grafted a replacement capillary tube using a donor from a auto parts store gauge. There is a web page describing this (I will look for it).

But really, if you paid money to N Hollywood for restoration then perhaps you should chat with them about what they did (and did not) do.

Here is the web page I was thinking of. I have not done this but it looks intriguing:

https://www.ply33.com/Repair/tempgauge
 
I have used the temp gauge repair method shown in Geo's link above to fix a half dozen gauges. It works well. However, the last time I did this repair I used dry ice for the cold bath instead of the salt/ice bath mentioned in the link. (Dry ice is both colder and cleaner).

However, as Geo said, if they charged you for repairing the gauge then you shouldn't need to add the capillary tube and expansion bulb.
 
I can't imagine them restoring a gage without soldering the bulb and tube to it. I'd give them a call!
 
CJD said:
I can't imagine them restoring a gage without soldering the bulb and tube to it...
Click to expand...

Me too but... I see that Jim has a TR3B. As I recall a few of the very last 3s got an electronic temp gauge (like a TR4). I suppose we might talking at cross-purposes here.
 
JimTR3B,
Geo. Hahn may be right...You may very well have an very early TR4 temp gauge. Take a look at your gauge face. If the high temperature figure is 250Âş F and he model number (above the needle hole) is BT2300/00 you have the TR4 unit.
That unit doesn't need a capillary line and an ether filled sending bulb, since it is electrical.
The TR4 sending bulb looks a little like the TR3 one and fits in the same hole, but it's an electrical part (sort of).
The connector to the gauge is simply a length of wire.
FRank
 
Geo Hahn said:
Me too but... I see that Jim has a TR3B. As I recall a few of the very last 3s got an electronic temp gauge (like a TR4). I suppose we might talking at cross-purposes here.
Click to expand...

My TR3B was 130 from the last one and it had the regular TR3 temperature set up. So I would disagree with your assumption. The TR4 items included the transmission and front brakes.
Charley
p.s. On the TR4 gauge you would also need a voltage stabilizer, which the TR3 never had.
 
charleyf said:
My TR3B was 130 from the last one and it had the regular TR3 temperature set up. So I would disagree with your assumption. The TR4 items included the transmission and front brakes.
Charley
p.s. On the TR4 gauge you would also need a voltage stabilizer, which the TR3 never had.
Click to expand...
Many of the change points were not "clean", meaning some earlier cars got built the later way, and some later cars got built the earlier way. I have no knowledge about temp gauges, but there were a lot of other things that were fitted to some cars and not others for months or even years.

Or the OP may have been deceived by an ad on eBay. I see a lot of mislabeled Triumph parts, and a neophyte might not recognize the difference.

At any rate, N. Hollywood Speedometer has an excellent reputation around here; I am quite confident they would never deliver a mechanical gauge without the capillary tube & bulb.

Also FWIW, although the TR4 gauge does need it, Smiths/Jaeger did make some temp gauges at that time that did not require the voltage stabilizer. Hard to tell for sure unless you check the part number.
 
luke44 said:
Has anyone run into a problem installing the sensor into the thermostat housing on the TR3? The threads just don't want to catch. Yet the threads are from a brand new/rebuilt gauge and seem fine. I’ve at least figured out it is 5/8 x 18 thread and not pipe thread, so, do I try a 5/8” x 18 bottoming tap which will cost me $26.00 to buy for a once in a lifetime use, or do I try a grade 8 bolt and may be cut a couple of slots in it with my die grinder and try to make a pseudo home made tap? Or a $49.00 new housing...Or, does anyone else have another other ideas? Frustrating. What should have been a 2 minute job to button it up has blown my whole afternoon :confuse: ... All comments welcome.

7290773824_c6d76f9d37_c.jpg


7290804198_38f6e4ddfd_c.jpg
Click to expand...
Moss motors send me this info on the size...

On May 13, 2022, at 10:16 AM, Moss Sales <moss.sales@mossmotors.com> wrote:


Hi Donwaldorf33,

Thank you for your email. The sensor thread will be 5/8" pipe thread (5/8" x 18 TPI)

Mark Evans


Sales Account Manager & Technical Support
 
Aside from this being a six-year-old thread, a tapered pipe fitting would NOT allow seating the shoulder on the ether bulb correctly before it became snug in the head. Just had one apart on an MGB a few days ago, the securing "nut" is not tapered, nor is the thread in the head. Mark may have been given wrong info.
 
The info i got from Moss Mtrs. about the size and thread for the sensor is below...
I bought a $25 mechanical gauge iEquus brand that came with adapters that did not fit for the TR 3.
I think i will take one of the adapters and have the correct thread cut.


From Moss...
Thank you for your email. The sensor thread will be 5/8" pipe thread (5/8" x 18 TPI)

Mark Evans Sales Account Manager & Technical Support
Direct: 805-679-7213 | Fax: 805-692-2525
Toll Free in US/Canada: 888-813-4693
 

Attachments

  • fitting.jpg
    fitting.jpg
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My sources don't even list a 5/8 NPT size. I think the guy at Moss misread his source, which said 3/8-18. 1/2 NPT is huge; 5/8 would be enormous.

There is a 5/8-18 SAE thread and a 3/8-18 NPT. There is also a BSP 3/8-19, which you might have. BSP pipe threads are not tapered, and they are still in common use. Smaller diameter NPT threads don't have much taper, so they might not look like a pipe thread.

You might want to try sticking a thread gauge into the hole and see if the pitch is what you expect.
 
I will try and find a gauge to do that... here is a short video of a similar product...


thanks for your input....
 
Don W said:
I will try and find a gauge to do that... here is a short video of a similar product...


thanks for your input....
Click to expand...
Hi Don, Is your housing an original , or a later replacement? If its a replacement, maybe the threads weren't cut as true as they should have been. The threads for the capillary fitting are the same as later electric senders, if you have one to compare to and possibly chase the threads.

I had a capillary fitting that was cross-threaded and wouldn't start. I got a matching nut from NAPA and was able to fix it - I'll try to figure out the size for you.

Jeff
 
TRopic6 said:
Hi Don, Is your housing an original , or a later replacement? If its a replacement, maybe the threads weren't cut as true as they should have been. The threads for the capillary fitting are the same as later electric senders, if you have one to compare to and possibly chase the threads.

I had a capillary fitting that was cross-threaded and wouldn't start. I got a matching nut from NAPA and was able to fix it - I'll try to figure out the size for you.

Jeff
Click to expand...
Jeff... it is the original thread ... for the past 15 or so years i have been without a temp. gauge. (i broke the original sender when reinstalling the motor) and just filled the hole with a TR4 electric sender. if you could find out the size it would be helpful...
(i haven't had any overheating problems) Thanks... Don
 
Don W said:
Would like to know the size of that adapter.....
Click to expand...
I am afraid I don’t know the threads on it its been on for decades.
but I guess it’ll be similar to that shown in the video above.
But Revington makes an interesting comment on the adapter
www.revingtontr.com

ADAPTOR MALE/FEMALE BRASS

This adaptor is primarily intended for use on TR2-3B with an aluminium thermostat housing where the water temperature gauge bulb screws straight into the aluminium casting. Due to dissimilar metal corrosion between the brass gland nut of the bulb and the aluminium casting the bulb and nut can...
www.revingtontr.com
 
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