Can a non-mechanic change the thermostat on. 2004 Monte Carlo with a 3.8 engine?
mechanic wants over $500 to do it 😕

 

Yes, it's a very easy thermostat to replace, it's right on top and only 2 screws hold the housing in.

Just follow the upper radiator hose to the engine and you'll see the housing, under the engine cover if you still have one.

Plenty of youtube videos show how to do it as well

 

Thank you, I’ll give it a try.
I looked for YouTube videos but couldn’t find any with that engine type. I’ll try again.

 

Its certainly one of the simplest maintenance tasks on a 3800. I'm hesitant to say 'any' non mechanic can do it because I know people that don't even have enough tools + mechanical aptitude to get the plastic cover off the engine (being sarcastic a bit).

There are a few pitfalls to watch out for:
-Make sure you also replace the seal / gasket.
-Look at the upper radiator hose- if it looks rotten /cracked, now is the easiest time to replace it. If the upper is bad, the lower likely is also.
-Make sure you understand how to bleed it. You need to get the air out (and conveniently there is a bleeder valve right on top of the thermostat housing) when you're done.
-Make sure you use compatible coolant. It came with orange GM dexool, but given its an older car - Id look to see what color the existing coolant is. If its green, you'll need a different coolant as dexcool and traditional green dont mix.
-Make sure the replacement coolant is 50/50 water mixed. They sell straight coolant (for you to mix on your own), but that can't be used as is.
-Its going to make a bit of a mess on the engine / under the car. Its the top of the cooling system so it won't be gallons, but there will be some.
-Be careful tightening the bolts - they go into aluminum. Its possible to over torque them with a big enough ratchet and blow the threads out. Ideally you'd torque them to spec with a torque wrench.


If you really would rather not do it but the price is what's stopping you, find a different mechanic. This is well under an hour's work and well under $50 in parts and materials. Either they're quoting added stuff you didn't ask for or they're intentionally trying to screw you. Either way, its time to find a different mechanic.

 

It is certainly an easy job if you are comfortable using a socket set. It is pretty straight forward and then you need to bleed the air from the cooling system. I would say maybe about an hour to do it all? And you can use any video of a 3800 in a Monte, Grand Prix, Regal or Impala.

I don't spend money with mechanics (I do all my own work). I know you pay a mechanic for their time, but seriously, $500 to change this T-stat? Seems very excessive.

 

Yes, it was totally easy! We are getting g ready to do a full flush cleaning on it now. Hope that is just as easy. 🤷‍♀️🙏😬

 

Just make sure not to mix the green stuff with dexcool. I always buy concentrated ACDelco dex and mix it 50/50 myself.

Flush it well, fill it up, bleed it, fill it back up, bleed it. Not awful, but does take a while because it needs to cool off and heat up and cool off and heat up.