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2009 replace thermostat on 4-cyl?

27K views 10 replies 4 participants last post by  bw77 
#1 · (Edited)
Out of town family member has asked me to replace the coolant thermostat on his 2009 Malibu 4-cyl.

I can't find a writeup on doing it, and since I don't have the car in front of me - is this straight forward or any tricks involved?

I have seen a flat rate time of 1.8 hrs, which seems like a lot based on other thermostats I have replaced.

Thanks.
 
#3 ·
It's in a very crappy place...kind of tough to get to the inside bolt. I had to move unbolt some brackets and what not to get clearance. Take your time...1.8 hours seems right to me if it's your first time. I have done it twice on our Malibu and I could probably get it done in about an hour now.

Do not overtighten the bolts to thermostat-housing...Good luck and let us know if you have any trouble.
 
#4 ·
I got to look at the car yesterday. P0128 which indicates thermostat needs to be replaced.
Looks like I need to move the metal coolant pipe which sits just above the inside bolt blocking
access. Planning to remove the engine cover to get a better look today.
 
#5 · (Edited)
I think that is an AC or heater hose line (not sure which one). I also unbolted some brackets and def took the engine cover off. Like I said, it's not too bad it's just the inside bolt on the housing sucks to get to. Be sure to drain all the coolant out. The thermostat is pretty low so it takes a lot of coolant in order to not have any spill out when you take the housing out. Let us know how it goes.
 
#6 ·
I replaced the t-stat this morning.

After removing the engine cover I saw that the metal pipe blocking access
to the inside t-stat bolt was the air injection pipe that goes up to the air
injection control valve. I released the black plastic nut and then I could
move the pipe around to access the inner bolt.

Some notes:

Did not have to lift the front end of the car.
Could not loosen the radiator drain valve by hand, had to use pliers.
Used a long 1/4" drive extension to get onto the t-stat bolts.
Quite a bit of coolant poured out when I pulled off the t-stat,
I had not drained the block, just the rad.

Engine cover was hard to get back on, never did it before.
Put it on the 2 ball studs first, then the throttle body.
I also removed the air hose between the air cleaner and throttle body and put it back on last.
Also disconnected the pcv hose from the engine cover.

I followed the instructions for warming the engine at 3000 rpms for 30 sec
at a time, but could not get the fans to come on. Temp needle is between
3 and 4 o'clock, but it always ran like that according to the owner.
Maybe the ect sensor reads a little low?
 
#7 ·
The 3 and 4 o clock reading is normal. All is good there my friend. Glad it went well. I personally would have replaced the temp sensor while you were down there (only because I've had 2 go out on me...which is why I replaced the thermostat twice). Figured coolant would go everywhere. Glad you got it fixed!
 
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#8 · (Edited)
Update 10 months later. P0128 returned. I replaced the ECT sensor and so far no more codes.

Not hard to replace, I moved the coolant reservoir. No coolant leaked out when I removed the sensor,
I was expecting quite a bit. I used an AC Delco sensor, it has sealant on the threads and a washer.

I tested the resistance of the old and new sensors.

Old: 2300 ohms @ 80F
New: 2000 ohms @ same temp

Lower resistance = higher temp. So the old sensor was reading 15% colder
than the new one.
 
#11 · (Edited)
Update, Feb, 2018

P0128 returned, but I was not able to drive out to BIL
and fix it myself. He took the car to a local shop.

Mechanic first said thermostat was bad, ect sensor was good.
He replaced thermostat with aftermarket part and no more cel.
A few weeks later, said thermostat was bad again, and ect sensor
was bad. Replaced both with gm parts.

Cost several hundred$ to repair.

I used AC Delco parts, about 3 years ago, and both went bad.

Told my BIL, next time the check engine light comes on, call me,
I'll drive out to fix it.

Mechanic said Malibu and Cruze are known for bad thermostats
and ect sensors.

Very disappointed in poor quality AC Delco parts.
 
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