Temp gauge never goes above 100 degrees. I did the test found in several other threads regarding grounding out the leads on the temp sending unit to determine whether it is the gauge or the sending unit. It is the sending unit. This might seem a stupid question but do I have to drain the cooling system to change this sending unit? My Haynes manual is mute on the subject but it does note that you must place teflon tape on the new sending unit before installing. I would appreciate any ideas.
Thanks,
Shawn

I would drain it out to do it (especially if its been a while since youve flushed it too.) If not then just drain a little out as this should lower the level of the fluid enough to replace the sensor without getting coolant everywhere. Hope that helps

Usually, the new temp. sender is supplied with sealant on the threads. If you have the new sender on hand, and screw it into the hole immediately after removing the old unit, not much coolant will be lost.

On the other hand, as posted earlier, if you haven't changed coolant recently, you could use this as an opportunity to drain, flush and replace the old coolant.

I don't like the idea of using Teflon tape on the threads. That sensor has to be grounded via those same threads, in order to work properly.

I recently changed my temp sensor. I didnt drain my system and i say about a tablespoon of coolant came out. Just used a ratchet and a socket to pull it out and put the new one in right away. Unfortunately this didnt solve my temp guage problem, 20 bucks for nothing , sould have checked for trouble code before then, could have saved 20 bucks

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--Adam--
1987 Blue GT 5-speed
IM AOL: GTFiero

No fear on it not grounding properly... The tape gets pretty much mutilated on the high pressure spots and grounds out A-OK. Put it in, then pull it right back out if you like, and you'll see lots of nice bright shiny bits where's it's been contacting. Of course, put new tape on again...

As for loosing coolant, dont' worry about it. just do it when the engine is dead cold (first thing in the morning). Then there's no pressure in the system, and if all the caps are left on you'll barely get a trickle out of it. Done it several times with rad fan switches.

No. It is self draining.

Any offending fluid will exit the hole without any assistance from you when the sensor is removed. JK

please do not use teflon tape on the threads. any certified mechanic will tell you the same thing. screw the new sender in nice and tight , it won't leak I promiss you unless theards in the block are bad or there is a crack in the block.
Don