-
Hi Guest!
If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
There are some perks with a member upgrade!**Upgrade Now**
(PS: Subscribers don't see this gawd-aweful banner
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
Temp gauge stopped working....any common cause?
- Thread starter Healey_Z
- Start date
Share this page
Randy Forbes
Yoda
Offline
Pull the sending unit out of the head (or radiator on earlier models) and put it into a pan of boiling water. Should read 212*F.
Lotuswins
Jedi Trainee
Offline
Healey Z:
If its the original guage, its the mechanical gas type utilizing a bordon tube behind the face plate. Most common failure is a leak in the tube or bulb, allowing the gas to escape. You can remove it and send out to a repair shop, or buy a new one which is close to original.
If its an aftermarket, electrical type then its a different animal. Start by checking for power at the guage, then the resistance of the sending unit to ground at temperature. That will tell if its the guage or the sending unit.
Let us know how you fare?
Jerry Rude
BJ8
Lotus Europa TCS 'Guenhwyvar'
If its the original guage, its the mechanical gas type utilizing a bordon tube behind the face plate. Most common failure is a leak in the tube or bulb, allowing the gas to escape. You can remove it and send out to a repair shop, or buy a new one which is close to original.
If its an aftermarket, electrical type then its a different animal. Start by checking for power at the guage, then the resistance of the sending unit to ground at temperature. That will tell if its the guage or the sending unit.
Let us know how you fare?
Jerry Rude
BJ8
Lotus Europa TCS 'Guenhwyvar'
Healeysince59
Jedi Warrior
Offline
You have lots of options for repair. Nisonger in the East, Moma in Albuquerque, Palo Alto Speedometer in Palo Alto, West Valley Instruments in So Cal all have been recommended on this and other forums. I sent mine to Foreign Speed in San Diego because I have dealt with them in the past.
Marv J
Marv J
Bob_Spidell
Yoda
Offline
FWIW, I believe they are charged with ether, which is a liquid (just barely) at room temperature (same stuff used in the old-fashioned toy bird that rocks back and forth into a glass of water).
My otherwise mechanically savvy father refilled one and tried to re-solder the bulb. Fired the bulb across the garage like a 50-cal bullet. Fortunately, we wasn't hit.
My otherwise mechanically savvy father refilled one and tried to re-solder the bulb. Fired the bulb across the garage like a 50-cal bullet. Fortunately, we wasn't hit.
Offline
Bob_Spidell said:
I think that's correct. I've seen one burst a leak right in front of me (hissing away). Once it's out, you're out of luck. The small tube that communicates with the bulb in contact with the coolant is somewhat fragile and if it's been wiggled a fair bit, can break or leak where it comes into the gauge. I'd seek a new one (as I've not seen how to repair it with ease).
Healeysince59
Jedi Warrior
Offline
This is a common repair, cheaper than a new one, and you keep the correct gauge. Mine (for a XK120 but essentially the same) will be about $130 but only because it needs a new capillary tube and the spring-like wire armor. To recharge and fix a leak would have been less than $100. They also clean and check out the oil pressure gauge.
If you want to try a DIY repair, go here:
https://www.ply33.com/Repair/tempgauge
Marv J
If you want to try a DIY repair, go here:
https://www.ply33.com/Repair/tempgauge
Marv J
Bob_Spidell
Yoda
Offline
Not sure about the safety gauge, but the tach and speedo indicator needles on my BJ8 are a press fit. If that's true for the safety gauge you can 'calibrate' without bending anything (at least intentionally).