Temperature Sending Unit

[sbailey05]

I can't seem to find a parts guy who can identify this sending unit and the 2 I got from rock auto are too large(thread size) to fit. Anyone know which sending unit this is? I believe my motor is a 87-88 305 off of a TBI truck that was swapped to my 79 carb truck. The temperature sending unit is the only gauge I can't get working after fixing all the others because I can't find the right sending unit.

[gunrac]

Not knowing exactly what you have could create an issue when ordering parts on-line or local. Go to a real parts store, where you may actually find a fella that knows something and hand him the unit. NAPA comes to mind. I'm sure it's common. May be older heads on a later model block. W/o ID # who knows. When you do find the right unit, ask him what yrs. that unit was used in.

[zieg85]

I agree.  You will probably find that you will had to change the end of the connector on your 79 wiring to accept the one that fits your engine.

this is for a 1987 and comes with a pigtail  http://www.autozone.com/engine-management/coolant-temperature-sensor/chevrolet/r10-1-2-ton-p-u-2wd/1987/8-cylinders-h-5-0l-tbi?filterByKeyWord=engine+temperature+sensor&fromString=search

or this may be the exact one you need  http://www.autozone.com/electrical-and-lighting/temperature-sensor/holley-temperature-sensor/chevrolet/c10-1-2-ton-p-u-2wd/1982/8-cylinders-l-5-7l-4bl-ohv/114273_0_0/?checkfit=true

[hatzie]

I agree.  You will probably find that you will had to change the end of the connector on your 79 wiring to accept the one that fits your engine.

this is for a 1987 and comes with a pigtail  http://www.autozone.com/engine-management/coolant-temperature-sensor/chevrolet/r10-1-2-ton-p-u-2wd/1987/8-cylinders-h-5-0l-tbi?filterByKeyWord=engine+temperature+sensor&fromString=search

or this may be the exact one you need  http://www.autozone.com/electrical-and-lighting/temperature-sensor/holley-temperature-sensor/chevrolet/c10-1-2-ton-p-u-2wd/1982/8-cylinders-l-5-7l-4bl-ohv/114273_0_0/?checkfit=true

The Packard 56 connector for the Obsolete GM Nailhead sender and the Tang sender are the exact same part.

The short answer...
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You have a 3/8 NPT sender hole.  1979 and 1980 are odd ducks.  They could have either 3/8" or 1/2" Tang senders depending on what engine was installed.  Hopefully the gauges are the same...  They probably are.
AC Delco Part # 8993164 3/8"-18 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1008, STANDARD MOTOR PRODUCTS Part # TS76 Looks like the sender on the end in the below picture.
 
The Long answer...
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There are several different temp gauge senders for the 73-91 squarebodies.  The earlier and later temp senders have a different Ohm range for the sender. 
This is a graphic from Letric Limited that shows several open terminal senders that GM used on cars and light trucks in the 1970's...  Ignore the part #s in the picture. I have the right ones listed further down.
 

 GM PN from the 79-84 parts books...
 AC Delco Part # 8993106 1/2"-14 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1049, STANDARD MOTOR PRODUCTS Part # TS71
 AC Delco Part # 8993164 3/8"-18 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1008, STANDARD MOTOR PRODUCTS Part # TS76
 
 For those with earlier trucks...
 Delco PN from the 73-78 Parts Books
 AC Delco Part # 1513321 Obsolete 1/2"-14 Thread; All W Gauges (Nail Head Connector)
 
 The Standard Motor Products TS6, Wells 1T1053, and even AC Delco G1852 "Drop In Replacements" don't have quite the same Ohm range as the original AC Delco 1513321 sender.  The gauge will read slightly high or slightly low depending on who made your sender.  This may be good enough for you.  You decide.   Edit: for 1973-1978 model trucks, see the thread Correct temperature sender and connector for 1973-1978 C/K trucks.

I was installing a 6.5L Diesel with a 3/8" sender hole like the OP in a 1976 chassis.  My solution was to use the 1981+ temp gauge guts with the 76 face, a painted needle, and a later model 8993164 sender.

 Here's a thread on another board about the obsolete Nailhead sender. 
 http://67-72chevytrucks.com/vboard/s...d.php?t=587190
 Letric Limited has a replacement sender that's pretty accurate above 140F.
 http://www.lectriclimited.com/electrical_devices.htm
 The C1 & C2 Corvette guys have hashed the obsolete 1513321 sender over pretty good with graphs of the Ohms Vs Temp on OEM and aftermarket senders...
 http://www.lbfun.com/warehouse/tech_...eCF-Thread.pdf

[VileZambonie]

Let me know when you have this resolved and I can move this thread to the tech section. Good info here. Thanks Hatzie

[sbailey05]

The connector to the sending unit was cut off/broken off so it was just a wire. However, it appeared to be the same blade end but I didn't measure them or really look to make sure they were the same size since the threading didn't fit and the wiring end/connector wasn't present.


Vile, Will do. Gonna get back on it tomorrow. Thank you!

[sbailey05]

Well finally got around to finding a place that had one of these. Turns out Autozone had a Duralast TU66 for an 87 that turned out to put the needle slightly before the middle of the gauge at 200-205 degrees(infrared thermometer). The old sending unit has a part number but I forgot to measure the new one and check the resistance before putting it in. The one that came out of the truck was part # AC127CM or I believe ACDelco Part 25037176. Seems to be working just fine and finally solved my problem.