Thermostat and sending unit

[jbgroby]

Hey,

Did some testing driving around the block to knock off the dust and all the gages seem to work except the water temp. The dolphin gauges are new, but the thermostat and sending unit are about 5-6 years old and sitting on a motor that starts about 3 months or so. Because of the cost, I'll grab a new water temp sending unit (Catalog #TS6469, off GMC site).

However, no listing for a Thermostat part number, anyone have a good number?

Thx,
Jake

[AZKen]

160 deg Stant 13006
180 deg Stant 13008
195 deg Stant 13009 (OE temp)

[jbgroby]

Thank Ken, I wonder why the OE temp was set so high at 195 deg? , what do you recommend?

[AZKen]

The list I found said OE was 195. I don't know if that is accurate. The 160 and the 180 are listed as "alternate". This is a designation used for older vehicles like ours and is safe to use. Thermostats do not fully open until about 15 deg above rated. I would use the 180 and see what the temp gauge reads and if the cap works properly.

[jbgroby]

I never though about the rad cap. Do they need to 'match' the temp of the thermostat?

[AZKen]

I was just saying, if the motor overheats, the cap will start expelling as a possible sign of wrong thermostat. A small point.
The 1960 stock 305 V6 truck takes a 7 LB cap. If you go with a overflow tank, some systems need a zero lb cap, I believe, in order to expel and suck back in. Some of the overflow kits include a radiator cap. Don't quote me on this, just a possible warning about cap pressure.
I would inquire as to other opinions but using a 180 Tstat and 7 lb cap will work and is very close to original. That could be called matching, using the correct parts will make them "match" what was intended by GMC. If there was an overflow/recovery tank offered in 1960, maybe we can find what lb cap was used if you want to go that route. But if radiator level is kept down a little, it should never spill out the normal tube. If you fill to the brim, it will expel......and then seek it's own level probably. Just so the coils are covered. My too sense. If you have a radiator correction lasting more than 4 hours, call your mechanic.

Looks like starting in 1963 the cap was 13LB (12lb-16lb rating/closed or open system). That must be when they started using factory coolant recovery.

[jbgroby]

Great, I grounded the wire and the gauge pegged to hot, so that proves she works. I was able to pick up a new sending unit, but NAPA did not show the 180 degree thermostat, which by the way must be frozen as the rad is cool. I will do an online search to find the thermostat.

[AZKen]

What did NAPA show?.............. Rockauto has the Tstats. 160/180/195. If temp gauge says OK and Rad is still cool.........that's the fabulous GMC V6 design!!

[TJ's GMC]

Originally Posted by jbgroby

Hey,

Did some testing driving around the block to knock off the dust and all the gages seem to work except the water temp. The dolphin gauges are new, but the thermostat and sending unit are about 5-6 years old and sitting on a motor that starts about 3 months or so. Because of the cost, I'll grab a new water temp sending unit (Catalog #TS6469, off GMC site).

However, no listing for a Thermostat part number, anyone have a good number?

Thx,
Jake

I'm currently running a 180 t stat and a 14 pound rad cap. No problems here. I leave the fluid 1 inch from the brim. Engine runs cool as normal.

[65barnfind]

If you live in a warm climate you don't need a 195, and it also depends if its a fare weather driver or a year round. I would stay away from the 160. I put a 160 in my 71 gmc and it has a long warm up time before it will run good because the water starts getting circulated too soon. In. My opinion a 180 would be perfect