After a run a couple of days ago, I smell the sweet after burn of anti-freeze. A smoke trail led me too under the expansion tank on top of the engine. The drip was coming from the coolant sensor area. No big deal just takes some effort to get it out.
Before I go to all the trouble, does it have a O ring? If so, easy enough, if not, I'll just order a new one and wait until it comes in to change out the leaking one. Doesn't leak when the pressure is off.
I did look at a bunch of pictures, and it showed a ridge just couldn't tell if it was a O ring.
Thanks.

 

The sensor fits in a 'tube' inside the tank so no coolant touches it.
I have seen several old coolant reservoirs with small cracks that drip/spray coolant onto the left exhaust area.
I thought it was the octopus heater hose but turns out the reservoir gets brittle and leaks often.

 

I think the coolant sensor is a hall effect type, so it doesn't actually have a liquid interface. It's more likely a tank leak.

 

The sensor doesn't actually interact directly with the coolant - it sits in a recess and can be removed without any coolant loss. So your problem is a crack in the tank, not the sensor o-ring.

Edit to acknowledge other replies typed while I was replying!

 

Thaks Bob, for the quick response, kind of a good news bad news but now I know to take it off and find the crack, or get a new one.
I did get pretty good at plastic welding working on all the old Triumphs' light switches. The trick for me was adding the extra plastic for filling.
Cold weather gives you time to do crazy stuff.

 

Just get a new one. These cars have such small coolant capacities that you don't want to risk a major leak that leads to rapid overheating.

 

New are CHEAP!!!!!!!!!!!!!!!

 

Be sure to keep your old cap, may need a spare since poor quality cars are plentiful.

 

^^ Agreed. I always keep the caps that still function properly. I believe I have two on my garage shelf. Both are aftermarket....

 

FWIW department;

the caps often fail early because they are over tightened, and warp easily.

The two o-rings do all the sealing, so the cap does not need much tightening at all, just snug plus a little. ( I learned that on this forum, of course).

Also, I find I can get the cap cross threaded if I don’t keep a little pressure on the center of the cap with my thumb while turning it.

Z

 

I hope this helps. The same thing happened to me; I thought it was the sensor. No, it's a crack in the reservoir. Replace it with a new one; they usually come with the cap and sensor included. You can buy them from an authorized dealer, on eBay, Amazon, and also on AliExpress. If the cap is in good condition, it's best to keep it; I kept the old one.

 

No brainer, on the way be here in two days.
Thanks all and will keep the cap and sensor on the part shelf.