New thermostat for Caprice

[kevm14]

The old one seemed to be taking too long to warm up and generally seemed to be keeping the engine cooler than it should be. So I replaced it with a Napa Premium one. Their most expensive! So it was $9.

This job took...at most, 10 minutes.

I do think I may have a little air bubble in the hose so next cold start I'll pop the radiator cap and let it warm up and hopefully bubble the remaining air through the upper hose. No leaks, and I was able to reuse the gasket.

Side note for funsies: look at my awesome giant alternator cable. See the 4 zip ties? Well, it was rubbing on that metal line there at the bend. Know what that is? Fuel line. I fixed that a month or so ago...but goddamn if that isn't the perfect recipe for an engine fire. Let me paint a quick picture: alternator cable rubs on fuel line, rubbing through insulation. It arcs to the fuel line which is probably a fine ground path, which then melts the metal open, exposing fuel to the electrical arc. Hilarity ensues. So, I put some zip ties on there. Plus one on the left to keep it off the accessory bracket. Yikes.

[kevm14]

Well I did the thing I said I would do and I'm still not happy with the performance of this thermostat. It just doesn't control engine temps very tightly when there's any kind of transient load. And by that I mean, temps could go up to 200°F just climbing the bridge (at 65 mph) and down to 190 or slightly below after a long coast. In steady state, it does find an exact 194°F but temps fluctuate too much for my taste. I will either put the old AC Delco back or order a new one from Rockauto to try. I love thermostat roulette. It's easy to change at least. The first replacement thermostat I put in the Maxima also had issues and I had to get an OEM one to make it work right.

[kevm14]

I checked my order history.

When I got a new radiator, I also got a new thermostat. It was an

AC Delco 12TP1E 19114386 Professional, Temperature: 195F; OEM Recommended Temp; high flow.

$4.50. August of 2013. It seemed to take too long to warm up so I guess I'll just put it back since we are heading into warmer weather. It sure did a better job regulating temps once warmed up.

There is also the

ACDELCO 13173 {#10207373} Professional; OE Temperature 195 Degree

for $7.51.

Oddly the cheaper one was in the Premium section of thermostats and the more expensive one was in the Standard Replacement section.

The cheaper one says "high flow." So maybe there is something to that (more than just marketing speak).

[kevm14]

Watching the performance of this new thermostat got me thinking...

Maybe the old thermostat really was "high flow." What my temp gauge does now is what I remember it used to do, and it's not even hot out yet. I think it really liked the high flow thermostat. So I'll either put the old one back or buy a new one. I can also confirm that it does seem to warm up a bit faster with this one. I know this cooling system is a very old design but I would have thought someone could make a thermostat that makes everything work properly...

I think this helps dispel another annoying car myth: higher coolant flow rates can lead to overheating because "the coolant doesn't stay in the radiator long enough." That is utter bullshit. Back in the day there were old wives tales of folks pulling their thermostats entirely and having engine overheat issues. That never happened. Some restriction at the water pump, in addition to the ~13 psi working pressure of the system, aids in avoiding impeller cavitation but the water pump will have restriction regardless of what you do with the thermostat.

[kevm14]

So a few weeks have passed. The new thermostat is performing better. Perhaps there was an air pocket that worked its way through. So I'll stick with it. Curious to see how it does when it gets really warm. That will really be the determining factor if I think I need the high flow one or not. Maybe I don't?