Engine Temp Needle Position Should Be Where...

[DrAnonymous]

I've been driving my resurrected 83 1.6 for a few months and am concerned about the way the engine temp acts. All the cars I've driven, when you warm up the engine, the temp gauge remains pretty constant. With this car, I get a lot of needle movement depending on driving, idling at a light, etc.

When I say a lot, I mean last month in warmer southern az temps it would be at about a third at first. Then if I'd end up at a light or two, needle would be just past half. If I drove for a good ten minutes, it would go back down. During the summer, I could see a swing from a quarter to three quarters. Now that its cooler, 55-60 in the mornings, needle hits only the second line, which seems too cool for running temp.

Short version then, how much should needle position change normally? Do I need to get a new t-stat?

[bscutt]

Normally the thermostat should keep it around mid-scale and under load it can rise to 5/8 or 3/4 scale but anything over 3/4 is too hot in my opinion. I don't like to see over 5/8 scale. The gauges aren't always super accurate but should be relatively consistent. If you are running at 1/4 scale I would find a way to measure coolant temp independently like thermometer in the overflow tank. If it's running much below 160-190 when fully up to temp, depending on thermostat, you probably need a new thermostat.

[TylerDurden]

I'd say stuck or sticky thermostat.

If stuck midway, it would allow cold water into the pump before the engine is warmed-up; and when the engine is warm, it would allow hot water from the bypass hose to enter the pump, making the engine hotter than it should.

A missing t-stat will do something similar, imo.

[DrAnonymous]

What temp t-stat should I buy?

[82vdub]

I've seen new Tstats cause fluctuations in gauges like this, but they typically settle out after a week or so (have no clue why this happens either). I would also suspect a Tstat issue. Simple to change on these, so that would be the first recommendation. You can probably run a 180 to 195 stat.

[CarlosA]

I wasn`t sure about this for a long time either, my fan kicks on at nearly 3/4 on both cars, but when coasting down a long grade at speed limit it can drop all the way down to the warm-up-bar. I don`t worry about it at all now because even in high temps the fan quickly cools and turns off even at idle.