Are all temp sensors created equal?

[Tony]

Related to my "project" post, is a temperature sending unit a temperature sending unit? The guy helping me says OMC part # 171960 is what I need, but after I buy it it turns out to have 1/2" threads when I need 3/8". Probably didn't figure that the Edelbrock manifold is not OEM.

So my auto parts guy and I browse his books and find a single post, 3/8" sending unit for early model Ford 302's. It is CarQuest part # TS58.

Are ohms involved with these things sending an accurate temperature? My guage is labeled a Kysor/Medallion, but there are no other specs written on it. I know the temp range I am operating at because we used a gun on it...should I go with this sending unit and see what it reads? This can't do any harm, right? Thanks!

[Air 22]

Tony...

Went thru a similar case w/ my 454MAG and used a 1/8 sender vs. the stock 1/2 inch . My new t-stat didn't have the OEM holes for the factory t-stats so I had to drill and tap a new one. You can screw in the sender hook it up and turn on ign to see if it will work b4 running. The guage will read 0 or just above if it has power. Run eng for 5-10 min to see if temp registers. If the sender is of the same temp range ie 0-280 and is the same brand as temp gauge should be ok. If you mix sender and gauge or diff temp sender your temp gauge will have mixed readings...ie..too hot = alarm or cold readings like 80-120 when its really at normal operating temp. Trouble shooting is a pain but if you mix brands thats all u can do. OHMs is not a big deal..if its off the gauge won't work . Keeping the parts the same saves many headaches.. :D good luck..let us know how it turns out. D wink

[RickR]

A 3/8" to 1/2" brass reducer might work. You can modify if so water circulates around the bottom of sensor.

Temp senders are NOT alike (different resistance)

[Murphy]

Also... and I'm a broken record on this cause I made the mistake... don't use teflon tape or any type of sealent on the sensor threads. A weak ground will give you a false reading.

Murph

[MOP]

Good point Murphy anything that needs ground must be installed with liquid sealer. Someting we ran into several times was our suppilers sending a dual station sender, that will drive you crazy. We even had a few marked with the correct OHMs readings. A slip of the finger in thier book can do you in!

[MOP]

Second post, the reason I always use liquid sealer is I have had my guys crack the Boss trying to tighten a leak. Another big point aluminum and brass don't like each other, disimilar corrosion can set in and make the contact go away.

[Cuda]

I used an adapter to reduce down to a 3/8's once, it worked out well. There is a sealant you can use that will conduct electricity, but I forget the name of it. My buddy has some. I'll find out later today what it is. I do know it's over $20 for a little tube of it, that's why I borrow his! :D

I have also used #2 permatex and it didn't insulate the sender. After installing it, I checked the resistance between the sender and the manifold.

[Tony]

Great advice regarding the ground, I guess I'll pull it out and wire brush off the teflon I used! About selecting the proper sending unit, I suppose I'll use a strategy I teach my 6th grade math students...guess and check!