Thermostat replacement

cntinuum

Original poster
Member
Dec 4, 2011
30
If the How To for replacing the thermostat is on here, I didn't find it. Got the pictures off another site. Those that replace the thermostat by only going thru the inner fender, more power to you! I removed the battery, battery tray(removed the horns so I could get to front side bolts), alternator and bracket above it. I also loosened the fan clutch and backed it off a few threads to get more room for my big hands. I am seriously considering leaving the top bar holding the battery in place off next time I remove it. Started at 2pm and finished at 8:30pm. Only one trip to the parts store. Bought a 18mm deep well socket and slotted the side to make a tool to R&R the coolant temperature sensor. Found the thermostat with a common problem of the rubber gasket up into the spring. Dropped one of the 10mm bolts behind the A/C compressor. Took about an hour to get it. Easy job, just a lot of crap to remove to get enough room and access to the parts to replace.

New thermostat was running just shy of 210. Will see how it does in the next few days. No puddle on the floor this morning so I am calling it good.
 

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Ed H

Member
Oct 18, 2012
167
I will be replacing mine soon. I am happy to hear it went well, and no leaks! Think of the money saved! :wootwoot:

Dropped one of the 10mm bolts behind the A/C compressor. Took about an hour to get it.
Glad to know I'm not the only one who drops stuff. Seems to happen to me all the time. At least you got it back! :crazy:

If I may ask, how much coolant did you drain from the radiator before removing the thermostat? I am really good at spilling stuff all over myself too, LOL. :rotfl:
 

Voymom

Member
Feb 3, 2012
2,523
cntinuum said:
If the How To for replacing the thermostat is on here, I didn't find it. Got the pictures off another site. Those that replace the thermostat by only going thru the inner fender, more power to you! I removed the battery, battery tray(removed the horns so I could get to front side bolts), alternator and bracket above it. I also loosened the fan clutch and backed it off a few threads to get more room for my big hands. I am seriously considering leaving the top bar holding the battery in place off next time I remove it. Started at 2pm and finished at 8:30pm. Only one trip to the parts store. Bought a 18mm deep well socket and slotted the side to make a tool to R&R the coolant temperature sensor. Found the thermostat with a common problem of the rubber gasket up into the spring. Dropped one of the 10mm bolts behind the A/C compressor. Took about an hour to get it. Easy job, just a lot of crap to remove to get enough room and access to the parts to replace.

New thermostat was running just shy of 210. Will see how it does in the next few days. No puddle on the floor this morning so I am calling it good.

Glad the repair went good for you! When we changed Phantom's t-stat my husband ended up shearing some wires that I believe went to the alternator. The replacement harness was a bit more expensive than replacing the thermostat itself :crazy:
 

mrphoenix80

Member
Jan 1, 2013
251
I have a friend who goes though the wheel well to get them. Not for me. I take off the engine lift bracket and remove the alternator. Thank God for my 15mm Gearwrench. Then the tstat is right there. As for draining the coolant I don't until I remove the lower hose and then the rest with the tstat. The lower bolt is a bit of a blind stab but I still get it.
I noticed the temp gauge is a bit low during this last cold snap. I decided to check it with my scan tool because I replaced cluster bulbs with LEDs and had the cluster apart. So did I get the needle on right or is the temp low? The scan tool showed 170F after a 45 mile trip. So it looks like its time. OH JOY!
 

bluenvoyerob

Member
Jan 7, 2013
7
I just finished this job up on Sunday. A PITA but now it actually reaches 210 on the gauge...and no more CEL. I only removed the alternator (and lift bracket). Having the battery out would have made it a bit easier. Something to note, make sure you orient the hose clamp (at the thermostat end) the same way it was originally. Rotating it to make it easier to install with pliers sounds logical, but the clamp "ears" get in the way of the back of the alternator. You'll find that out once you spend the extra time trying to install the alternator, only to realize you have to step back again! :hissyfit:

I thought someone asked here how much coolant drained from the system... I filled mine back up with about 2 gallon and a pint. Original fluid looked nice and clean for 85,000 miles but is replaced it with a new mix (50/50 with tap water).

20130126_171818_800_zps6490408c.jpg
 

jake 03

Member
Jan 3, 2013
28
Glad that worked out for you!
I always remove the front tire and go though the fender well, cuts the replacement time down to 10-15 minutes
 

Tmn8tr

Member
Jan 22, 2013
12
What the heck! did they all go at the same time? I got into mine from the front, pulling the Alt, engine lift bracket, dumped the coolant (just under 2 gal) out the hose on the bottom of the rad. I tried to get into it from the D-side wheel well, but my inner fender is steel and there is only about two inches between it and the frame rail. Not feeling like slitting my wrists at this point, I opted to try to pull it from the front. The problem I ran into was that the hose clamp ears were at the 5'Oclock position from the driver's side of the block. No room for hose clamp pliers. Two choices, 1-feel around and blindly unbolt the flange from the block and remove the whole mess, pull and replace the hose outside the vehicle. Or 2- break out the sawzall and cut the t-stat housing in half, pull the hose and poss. have an easier time removing the rest of the t-stat housing with out the hose. Well I did both, first trying the first option, fiddling around dropping the wrenches and sockets who knows how many times, then after 45 min. went to #2, not too concerned about shavings in the water jacket since the lower end of the hose was disconnected, and the thermostat was on the other side, and coolant was still running out. Zip, and it's off. I reassembled it and noticed the wires to the CTS (I was replacing)were cut, no doubt an attempt to turn off CEL by ignorant so and so somewhere. (probably the stealership that sold me the truck)>http://gmtnation.com/images/smilies/hissyfit.gif
Reassembly went without any issues until I got to the lower end of the rad. hose when the fine piece of GM hose clamp shattered, breaking the ears off and biting a hole in my hose.http://gmtnation.com/images/smilies/hissyfit.gif Back off it came, and off to O'shucks for a new hose and a pair of SS worm drive hose clamps. I thought the spring clamps were nifty the way they stayed open, but I could have lost an eye if I hadn't had my safety glasses on! Not to mention cost me an extra $30 for a new hose. I do think it would have been easier if I could have pulled the fan off.
Well, sorry to be so long winded on my first post. I had to vent!http://gmtnation.com/images/smilies/biggrin.gif
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
seanpooh said:
Tap water as in well water or city water? I thought it was best to use distilled water...

That's what I thought,too.
However, the owners manual just calls for "Clean drinkable water".
 

mrphoenix80

Member
Jan 1, 2013
251
Dex cool bottle asks for "tap" water. I don't remember the reason. I think it came up in class once but it went in one ear and out the other.
 

bluenvoyerob

Member
Jan 7, 2013
7
seanpooh said:
Tap water as in well water or city water? I thought it was best to use distilled water...

I went with city tap water. The owner's manual and GM repair manual just called for clean drinkable tap water. Another source said deionized water. Apparently the chlorine in city water must not affect aluminum like it did when mixing with the green stuff...that's what I'm thinking.
 

navigator

Member
Dec 3, 2011
504
bluenvoyerob said:
I went with city tap water. The owner's manual and GM repair manual just called for clean drinkable tap water. Another source said deionized water. Apparently the chlorine in city water must not affect aluminum like it did when mixing with the green stuff...that's what I'm thinking.
I used distilled water in mine. Our well water has too many minerals(mainly iron) that I don't want floating around in my engine. Floating around in our body is ok :smile:
 

sawicksted

Member
Dec 7, 2011
366
jake 03 said:
Glad that worked out for you!
I always remove the front tire and go though the fender well, cuts the replacement time down to 10-15 minutes

So if you remove the tire and the inner fender it only takes 15 minutes to replace the thermostat? Some other person took 6.5 hours in this thread...I have the 4.2 I6
Just wondering how much time I need realistically to do the swap.
 

jbacklund

Member
Dec 16, 2012
118
sawicksted said:
So if you remove the tire and the inner fender it only takes 15 minutes to replace the thermostat? Some other person took 6.5 hours in this thread...I have the 4.2 I6
Just wondering how much time I need realistically to do the swap.

I'd say 4 hours would be realistic if you havn't done the procedure before.
 

Sparky

Member
Dec 4, 2011
12,927
Distilled is cheap so I prefer to play it safe and use that. Odds may be slim of issues using tap, but I figure it is worth the extra couple bucks to not have to worry about it at all. Especially since my city water is all kinds of gross.
 

Voymom

Member
Feb 3, 2012
2,523
You can also get dexcool and another brand that is premixed 50/50...that's what we did when we switched ours out.
 

sawicksted

Member
Dec 7, 2011
366
I have been putting off this repair for a while now. I don't get any CEL SES lights at this point. I have cleared the p0128 code a few times over the past few months. I will attempt this repair soon but I am concerned about disconnecting the battery as there have been issues with blown actuators (HVAC system) indicated by other members.
So....the question is what should I be doing to make sure there is no damage done to the electrical system / whatever seems to get blown? I plan on cleaning the throttle body first and then driving for a while so the pcm resets??? (not sure about this) Then I will do the thermo swap.
Is there something I can do to garuntee there will not be any electrical issue.

Thanks for any help guys.
 

CaptainXL

Member
Dec 4, 2011
2,445
bluenvoyerob said:
I filled mine back up with about 2 gallon and a pint. Original fluid looked nice and clean for 85,000 miles but is replaced it with a new mix (50/50 with tap water).

Please tell me you didn't mean to say "tap water". Anyone who has ever replaced coolant knows to use distilled water. Its like what? .50¢ a gallon at the super market.

I also recommend not using the (Made in Mexico) ACDelco thermostats. Two of them I tested were faulty out of the box. They only open 1/4 of an inch in boiling water. One I received looked used and had coolant and corrosion on it.
 

sawicksted

Member
Dec 7, 2011
366
jbacklund said:
I'd say 4 hours would be realistic if you havn't done the procedure before.

Ok, Thanks for the heads up. Any thoughts on the pcm reset issue that some people report when doing this repair?
 

Mark20

Member
Dec 6, 2011
1,630
CaptainXL said:
Please tell me you didn't mean to say "tap water". Anyone who has ever replaced coolant knows to use distilled water. Its like what? .50¢ a gallon at the super market.

I also recommend not using the (Made in Mexico) ACDelco thermostats. Two of them I tested were faulty out of the box. They only open 1/4 of an inch in boiling water. One I received looked used and had coolant and corrosion on it.

You can use tap water but I choose to use distilled as we have very hard water from the tap.
 

CaptainXL

Member
Dec 4, 2011
2,445
Mark20 said:
You can use tap water but I choose to use distilled as we have very hard water from the tap.

Sure you can use tap water and it will work but it's not the best thing to put in your radiator with all the chlorine and minerals. It will actually reduce the performance of the mixture.
 

jbacklund

Member
Dec 16, 2012
118
sawicksted said:
Ok, Thanks for the heads up. Any thoughts on the pcm reset issue that some people report when doing this repair?

No sorry, I didn't unplug the battery. Didn't find it necessary, just made sure not to short circuit the cables to the alternator.
 

97blazer

Member
Nov 23, 2012
39
Frankly I'm amazed that people are going to all this trouble to replace the t-stat. Through the fender works. What you will need is a long extension or two together and a so-called wobble socket or adapter. One bolt is easy the other a bit more of a challenge. It's not a slam dunk but, to me, way easier than removing all that other stuff including the fan. Seems to me what I did do is leave the hose attached, reinstalling it on the new t-stat before installation.

HTH
 

amweaver47

Member
May 15, 2012
122
I went from the top when I replaced mine. Was a huge PITA but the job got done. I was able to get one arm from the back by the brake booster and one from the front to work on it. Carved the hell out of my arms and took forever. Probably about 4 hours counting the time I spent bolt fishing. Try not to take a coolant bath working on it too. I was pretty careful and got most of it in a pan but things could get ugly if you aren't paying attention. Going through the wheel well might be easier but it just seemed backwards to me, maybe I'm just stubborn. :undecided:
 

tbags4ever

Member
Jan 13, 2013
10
sawicksted said:
I have been putting off this repair for a while now. I don't get any CEL SES lights at this point. I have cleared the p0128 code a few times over the past few months. I will attempt this repair soon but I am concerned about disconnecting the battery as there have been issues with blown actuators (HVAC system) indicated by other members.
So....the question is what should I be doing to make sure there is no damage done to the electrical system / whatever seems to get blown? I plan on cleaning the throttle body first and then driving for a while so the pcm resets??? (not sure about this) Then I will do the thermo swap.
Is there something I can do to garuntee there will not be any electrical issue.

Thanks for any help guys.

Just replaced mine today. Can't fathom how some can go through the wheel well. I had the piece of the body along the frame that left only a couple of inches of room to play with, so I didn't even try. Here's some pointers to possibly make it go quicker:
- pick up some ratcheting wrenches if you don't have any. The lower alternator mounting bolt has ZERO clearance to use a socket on (A/C line is in the way)
- Also, I would try loosening the lower bolt before the uppers. You know how the first bolt can be loosened by hand a bit easier when a few others are still in place? The Haynes manual had me removing the top 2 first, which made the lower one a BEAST to remove with a simple wrench.
- I had the hose clamp on the rear side of the thermostat housing as others have mentioned, so I just removed the thermostat housing bolts first. Then I could fanagle the housing and hose around to get to the clamp more easily.
- I would remove at least the battery cover as well. It's really tough to get the alternator out unless that and the engine hoisting bracket are removed.

I hope that helps you. I probably took about 3.5 hours, but only because I had such a hard time with the lower alternator bolt and the hose clamp (I also replaced my driver's side bearing/hub assembly, which had me in the garage all afternoon).
 

tbags4ever

Member
Jan 13, 2013
10
sawicksted said:
I have been putting off this repair for a while now. I don't get any CEL SES lights at this point. I have cleared the p0128 code a few times over the past few months. I will attempt this repair soon but I am concerned about disconnecting the battery as there have been issues with blown actuators (HVAC system) indicated by other members.
So....the question is what should I be doing to make sure there is no damage done to the electrical system / whatever seems to get blown? I plan on cleaning the throttle body first and then driving for a while so the pcm resets??? (not sure about this) Then I will do the thermo swap.
Is there something I can do to garuntee there will not be any electrical issue.

Thanks for any help guys.

I realized I didn't address the electrical issue. I didn't have any issues with mine. I can't fathom that removing a battery connection would create issues with other electrical components. Don't we have to remove the battery to replace it periodically? I would just disconnect the battery, because clearances are so small and I wouldn't want to risk arcing with the alternator contact.
 

mrphoenix80

Member
Jan 1, 2013
251
tbags4ever said:
pick up some ratcheting wrenches if you don't have any.

Gearwrench to the rescue!!! I would recomend them to all. After you use them you won't be caught dead without em.

Any body here remember the OLD style ratchet wrenches? The ones that only had like 6 teeth in them.They might have been worse the a 12 point box end.:biggrin:

As for the a/c line I give it a LITTLE "adjustment" for a bit more clearance. I personally don't remove the battery cover, but the lift bracket has to go. I do unhook the battery. That kind of arc welding always makes me jump.:redface: The last one I did was 45min start to finish, and I only used air on 1 bolt (the burried one on the lift bracket). I tried the 1/4 inch by 3 foot extension in the wheel well and found my big claws won't fit in that opening. So I don't put em there. Also I have found the same method works on the 4's and 5's also. So after doing about 50 of them it easy to do.
 

MAY03LT

Member
Nov 18, 2011
3,420
Delmarva
tbags4ever said:
Can't fathom how some can go through the wheel well.

For real. I've seen it done through the wheel well but no thanks not for me:no:

mrphoenix80 said:
Any body here remember the OLD style ratchet wrenches? The ones that only had like 6 teeth in them.They might have been worse the a 12 point box end.:biggrin:

I've got some back in the day craftsmans like that, they have like a 45 degree swing lol. I can't really knock them since they saved my biscuits a few times.
 

WarGawd

Member
Sep 2, 2012
468
sawicksted said:
I have been putting off this repair for a while now. I don't get any CEL SES lights at this point. I have cleared the p0128 code a few times over the past few months. I will attempt this repair soon but I am concerned about disconnecting the battery as there have been issues with blown actuators (HVAC system) indicated by other members.
So....the question is what should I be doing to make sure there is no damage done to the electrical system / whatever seems to get blown? I plan on cleaning the throttle body first and then driving for a while so the pcm resets??? (not sure about this) Then I will do the thermo swap.
Is there something I can do to garuntee there will not be any electrical issue.

Thanks for any help guys.

My local Canadian Tire sells a $10 memory saver that I plan on using when I get the weather to cooperate to change my battery and install my PCM4 pcm - May03LT has advocated their use in some of his videos, you may want to track those down.
 

Tmn8tr

Member
Jan 22, 2013
12
My rear actuators did go with that repair, but I just assumed it was a coincidence. The guys at the FLAPS said they just "do that". It was an easy enough repair, even though I would have rather not have had to spend the cash, or the time. Another reason I don't think it had anything to do with the batty being disconnected is I had to replace my T-stat a total of 3 times over the course of a two-week span. The OE seemed to be fine but I replaced it anyway since I was doing the CTS. The one I put in from O'Reilley wouldn't close. Got one from NAPA (looked the same BTW), same problem, then #3 came from an Ebay Discount parts seller, and it works fine. (upon disassembly I noted the OE spring was a good inch longer than the O'Really one...HMM!)
ANYWAY! I replaced the rear HVAC actuators between T/S #1 and #2. and for #1 I didn't D/C the battery (shame, shame):wink:
so that's my 2 cents.
>T
 

CaptainXL

Member
Dec 4, 2011
2,445
97blazer said:
Frankly I'm amazed that people are going to all this trouble to replace the t-stat. Through the fender works.HTH

It's impossible to torque the bolts using a swivel and 24 inches of extensions going through the wheel well. Its not a straight shot. Once the alternator is removed (which is not difficult at all) the thermostat is right there and much easier to tackle.

When working on anything electrical always remove the black negative battery cable. This ensures not only your safety but it ensures sensitive electronics don't go up in smoke. If the red alternator cable is removed and accidentally touches any metal ground the battery can get damaged.
 

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