Which way to face thermostat


moliva1568
07-28-2012, 11:43 AM
I've got a 1974 pontiac 455 and I'm trying to change the thermostat. I forgot to take note of which way the old one was facing. The old one has "to radiator" and the new one doesn't. So I'm not sure how to put it in and based on the direction of the housing, I don't know which way to face it. Picture 1 and 2 are of the new thermostat and which way it would go. Picture 3 is the old thermostat which says to radiator but I still don't know which way it should go. Picture 4 is the way the thermostat housing sits. At first glance I would think it went the same way (pic 1). But based on the old thermostat and the "to radiator", it looks like it should go the way of pics 2. Once you clear that up for me, how do I know which side of the new thermostat should be the "to radiator" side and if it goes like pic 1, it doesn't actually face the radiator? Please advise.

Thanks

oldblu65
07-28-2012, 12:06 PM
I've got a 1974 pontiac 455 and I'm trying to change the thermostat. I forgot to take note of which way the old one was facing. The old one has "to radiator" and the new one doesn't. So I'm not sure how to put it in and based on the direction of the housing, I don't know which way to face it. Picture 1 and 2 are of the new thermostat and which way it would go. Picture 3 is the old thermostat which says to radiator but I still don't know which way it should go. Picture 4 is the way the thermostat housing sits. At first glance I would think it went the same way (pic 1). But based on the old thermostat and the "to radiator", it looks like it should go the way of pics 2. Once you clear that up for me, how do I know which side of the new thermostat should be the "to radiator" side and if it goes like pic 1, it doesn't actually face the radiator? Please advise.

Thanks
The side with the exposed spring goes toward the engine block ( as pictured ) and the side with the " tower " goes toward the upper radiator hose .

moliva1568
07-28-2012, 12:13 PM
So "to radiator" actually means to the radiator hose? Which would mean the top of the thermostat would look like north/south?

moliva1568
07-28-2012, 01:41 PM
After rereading your post oldblu I think I've been overthinking this. To radiator just means the top and the spring goes at the bottom toward the engine. I thought it had to sit a certain way too. Thanks

moliva1568
07-28-2012, 04:39 PM
So I changed the thermostat and the temperature sensor. I let it run with the cap off and heat on to get any air out. Now at idle it sits a little above the 210. It's only 70 degrees today and I worry where it would be if it were 95. Anything I should do related to what I changed today which might correct this? Right now I have mostly water in the system until get more bottles of coolant. Could that be causing this? Just trying to get some opinions before I start moving to more expensive replacements like the radiator. The picture is in park at idle. If I give it gas while still in park the gauge actually comes down???????

Thanks

MagicRat
07-28-2012, 11:39 PM
Some thoughts.
1.What temperature rating thermostat did you get?
Thermostats are engineered to open at a predetermined temperature, which is usually stamped on the body of the stat, and should be recorded on the packaging it came in.
Usually the temps are 160 F, or 180 or 195.

160 stats are too cold for automotive use and should not be used for ordinary driving.

180 stats are a great general purpose stat for non-computer controlled cars like yours.

195 stats usually go in computer controlled cars. They will work fine in most carbureted cars, but are not ideal for summer use. Great for winter, though.

If your car is running warmer than usual, it might be the new stat is a 195, and the old one was cooler.

2. Your factory temperature gauge, like most older OEM electric gauges are not at all useful for telling you the actual temperature the car is at. At best, they are okay to tell you relative temperature, that is, if the car is running hotter or cooler than 'normal', but are useless for telling you how much the temp difference is in degrees.

I suggest you install a good quality aftermarket gauge package, with 2-inch gauges in a panel that can attach to the bottom of your dashboard. I find a mechanical coolent temp gauge, mechanical oil pressure gauge and a volt meter is the most useful.
Basic name-brand packages are not that much money and are quite accurate. The fancy race-style gauges are quite expensive and are not necessary.

The alternative is to just drive the car. So long as the gauge doesnt swing too far into the hot zone, you should be fine.

moliva1568
07-29-2012, 03:43 AM
The thermostat I got was 195 which is OEM according to what I found. The old one was also 195. The car seems to be running warmer than it has the last few years which is what prompted me to change the thermostat. The water pump is about 2 years old I believe.

I thought about going to get a new gauge because I know this factory one isn't all that great. I've been considering that for a while as part of my "restoration" anyway. I guess I'll drive it like you suggest and keep an eye on it. I have an exhaust leak at the manifold. Could that be throwing off the reading too? It's on the opposite side of the temperature switch but could it still affect how it reads?

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