Wife's CX-7 kept throwing P0126 code. Same as my car did last winter, so I replaced the thermostat in my car (took about 1.5 hours, not terribly difficult).

Wife picked up a new thermostat for her car ($30) instead of taking it to the dealership where they wanted around $450 to replace it.

The damn belt tensioner on her car is located behind the front right wheel, in the wheel well. Okay, not a big deal. Jack the front end up, remove the wheel and sure enough, I can see the tensioner - sweet! Wait....what the hell? The tensioner says "Lift" on it with an arrow pointing up towards the left. I have to force the tensioner up to the left to release tension on the belt. This is not a one person job anymore.

I talk with my step-dad (used to be a mechanic and he's got a ton of fun tools, he just lacks an in floor car lift. We agree on a day to do the work.

I got to his place two nights ago and we get to work on the car around 5:45pm. The tensioner is almost butted up to part of the frame so we can't get a breaker bar on it and you cannot get any kind of socket wrench on it either. We were left with using a 14mm wrench and then we had to take the 15mm wrench and hook it on the back end of the 14mm to create an arm for leverage to left that tensioner pulley up....huge pain in the ass. Even with pushing the tensioner up we couldn't get it pushed high enough due to lack of room and it took 15 minutes to pull the belt off. After screwing around trying to get the tensioner and then getting the belt off, it was now 6:30.

The engine was still too hot to do work so we had to set up two machine shop fans and let them blow air across the car, under the hood for about 30 minutes. 7pm comes around and now we have to remove the power steering pump - should be simple enough. On the left side of the pump is a pulley for the belt we just took off and behind it on the bottom is bolt #3 that holds the pump in place - this was a bitch to get to. 25 minutes later the pump is off and now I can see the thermostat. It has two hoses on it and just below it is the alternator.

Now that I have access to the thermostat, I drain the radiator (10 minutes later she's done pissing). I take a couple of rags and stuff them under the hoses on the thermostat since it sits directly above the alternator and I don't want any coolant getting on it. I fight with the hose clamps and get them off after about a 15 minute battle.

3 bolts on the alternator, two on top are easily removed. The third one on the bottom right you can't see and it sits back behind another hose that runs up next to the headers. I had to fight for enough space to cram my big mitt, a 1/4" socket wrench with a 4" extension and 8mm socket back there....only took me about 20 minutes to get the thermostat off.

It's now almost 8:15 when everything is finally off! Nice! Time to put it back together with the new thermostat.

The new thermostat goes on very quickly, 5 minutes all bolts are in and she's tightened. Now it's time to fight with the damn hoses and clamps that attach to it. My hand slipped and I got met with a piece of metal that slid under my thumb nail about 1/8" of an inch and hurt like hell and started bleeding, so I took a break. My step dad fought with the hoses and clamps for about 15 minutes and go them on. He came and got me, told me the hoses were back on, but he had to take a call.

I reattach the power steering pump. I put the plug back into the radiator. The time is now almost 9pm. Here comes the really fun part of putting the belt back on.

Using the handy dandy diagram of how the belt runs across all the pulleys, we get it back on to a point. Now it's time to fight with the stupid ass tensioner again. We spent around 30 minutes trying to get the belt on and we were having zero luck. We took a 10 minute break, went back and assessed the situation after finding a couple videos online about replacing the belt. I had to remove the plastic covers in the wheel well so we could get to the bottom right pulley. We reconnected our makeshift lever on the tensioner and we must have got it hooked up at just the right angle because we were able to move that tensioner another 1-2 inches further than we could before and we were able to slip the belt over the pulley! Success!

Time is now 10pm and everything is back on in the wheel well and the tire is on and the car is back on the ground from the floor jacks. In goes the coolant (50/50 mix) and it takes about 20 minutes to fill the radiator, let her run and about 1.5 gallons of coolant to get the radiator and coolant reservoir filled. I reset the ECU and go home. The check engine light doesn't come back on, but the car's fan on the radiator is making a high pitched wail that it didn't make, especially when the AC is running.

The car wasn't over heating so I didn't bother with the new noise and would look into tomorrow. I got home, parked in the garage and turned the car off, removed the key from the ignition and the cooling fan came on and ran for about 10 minutes....all while making the high pitched wail (like the fan was running faster than it should have been). It eventually stopped and I went in, cleaned up more and got to bed around 12:15am.

Wife drives the car, tells me that fan noise is very audible while she's driving down the highway when the AC is on. I started looking online for possible issues that come up with the thermostat change on a CX-7, but nothing.

She gets home after work and I let the car sit for a long while to cool off. I start looking over it all again to see if maybe something was loose that would contribute to the noise and I didn't find anything. I was about to call it quits on my search when I decided to jam my hand/arm down behind the radiator to make sure the thermostat hoses are still on and no leaks when I felt something soft that shouldn't belong there.....

I pulled out a rag that was still stuck in there, in the passenger side's radiator fan. I pulled the rag out and started the car up, turned on the AC - no god awful fan whine! I drove the car around for a bit with the AC cranked and no unwanted sounds.

I don't mind working on cars, but never again will I work on this CX-7 if it requires the removal of the serpentine belt. Holy hell was it a pain in the ass. Nearly 5 hours to change out the thermostat on the car. I guess that beats spending almost $500 at the dealership to get it changed out, but I can see why it would cost so much based on the time I wasted doing it.