Does it actually "touch" the coolant, or is there a thin wall between it and the coolant?

Another way of asking this...if I take it out would I be wise to drain the coolant first?

Having just redone the engine harness, the temp gauge is no longer working (and it was before I did the rewiring). I'd like to pull it out and test it, but not if I have to drain the coolant to do it.

Of course I guess I can just idle it for awhile and watch the resistance change. Anyone know what typical values are?

Thanks,

John
1987 XJ-S V12, 62000 miles

 

Yes, it touches coolant. If you work really fast you can remove the old one and stuff the new one in the hole with minimal loss of coolant. Otherwise, drain off a bit.....and then re-bleed the system.

First though, remove the wire from the sender. Turn the key "on". Touch the sender wire to ground. The needle on the gauge should go all the way to hot. If it does, the gauge and the wiring to the gauge are OK....and you have a faulty sender.

Cheers
DD

 

Thanks Doug! Must have been a coincidence, but from running your test the sender is bad. Now to find a new one...

Regards,

John
1987XJ-S V12, 62,000 miles

 

Got a "new" one (made in Italy no less) from RockAuto. I was too lazy to drain the coolant, so I stuck a rag under it and unscrewed-screwed very fast. It now works.

Thanks!

John