I have a 2005 Buick Century with a 3.1L engine. Here’s my problem: The engine takes too long to warm up in cold winter weather. It runs too hot in the summer. The radiator fans are working at both high and low speeds. Is it possible the thermostat is stuck at a midway position between fully closed and fully open? Also, I found two thermostats on an auto store’s website that can fit my car. One has the “OEM recommended temperature” of 195F, while the other has an “alternate temperatures” application of 180F. Is the 180F thermostat for warmer, tropical climates?
More likely a previous owner took the thermostat out, I recommend running OEM of 195
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Why not just put a new thermostat in and see what happens ?
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Two possibilities (at a minimum): Your thermostat is stuck halfway, or it’s stuck full open and something else is causing the high summer temps, like a partially-plugged radiator. So I’d replace the thermostat, since that would be needed in either case. I’d use the 195F thermostat.
Is the coolant in good shape? Any way to view the inside of the radiator for plugging?
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When was the last time you drained and flushed the system?
If the answer is “I don’t know”, then it’s past time to drain and flush the system.
DIY?
Buy a new, quality, thermostat and test it in a glass of water (see youtube).
Drain the system and remove the thermostat. Use plastic to cover all connectors (A/C and Alternator) that may get wet then flush all hoses/radiator forwards and backwards with a garden hose at low pressure (system is designed for less than 20psi)
Grab a wet vac and suck water out of the hoses. Some water may stay in the system, so buy 100% anti-freeze (not 50/50) to refill the system. You’ll need to know the capacity of your system and do some math, also buy a good tester. Fill it with a 50/50 mix (distilled water) enough that you can run the engine. Run it, then test the mix…add more, test, repeat till full with a 50/50 mix
Sounds complicated, but once you figure it out it’s a piece of cake.
Pay someone to do it?
Tell them you want a complete system flush and new thermostat. Be sure they have pro equipment that can create a vacuum in the system to remove and replace the fluid (see YouTube for examples)
Possible air pocket in the cooling system… But a OE temp t-stat is cheap, labor might be about 2.4 hours, but worth trying…
Me I would check for any codes, check live data for the ect and then hook up my coolant pressure gauge at 0 pressure to start with and start the vehicle cold to watch the pressure to see what it does as the vehicle warms up… also check temps at the t-stat, rad hoses, heater hoses, and across the radiator to see what the readings are… making sure the coolant level is full is a given…
If it still has Dex-cool in it and if it is low on coolant then you may be replacing a whole lot of parts soon…
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Good point about pressure and the cap, cheap to pressure test the system and cap, and check temps elsewhere. Lots of possibilities.
The engineers designed your cars cooling system to run at 195 degrees, the faster it gets there, the sooner the engine is the most fuel efficient.
Generally, people put in a lower thermostat to get heat sooner. I don’t see a benefit in hot climates to opening the stat sooner…the system will still aim to keep the fluid at 195 degrees.
I’d be looking at the thermostat.
You may find it looks something like this.
Tester
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Not the same car but when we had a car slow to warm up in winter it was the thermostat that was the problem. Back to normal with a new thermostat. Had our trusted mechanic do it for a reasonable price.
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The old thermostats tended to stick closed. The new $25 ones seem to stick open, but I haven’t had a bad one in years.
Along with flushing the coolant, new oem thermostat, and checking the water pump, bugs clogging the radiator can reduce performance. Bug screens aren’t used much anymore.
The most common “faulty thermostat” failure for me is warped. The warped valve doesn’t seal completely, so it acts like it is partially open all the time. Asking a shop to removing the existing thermostat for a look-see is the OP’s first step. If the thermostat has never been changed since the car was new, pretty good chance it is now warped. They live in a tough environment.
Pay a shop to look at it ? Just have a new one put in and be done with it.
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Yep, this is one of those jobs that cost 90% for the labor and coolant, 10% max for the thermostat. If it’s out, a new high quality one needs to go in.
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+1
If someone is paying the labor for “inspection” of their 19 year old thermostat, it would seem to me that it just makes a lot more sense to go ahead and replace it–for no additional labor cost, and not a whole lot of money for the new part.
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The new thermostat may be faulty.
And just how often is that going to happen ?
What new T-stat???
From the posts above
OK, you mean the new T-stat might be faulty before it is installed… Check it before install…
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