Engine Light - Thermostat or Cooling Sensor? - Chevy Colorado & GMC Canyon
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 48 (permalink) Old 11-09-2010, 01:18 PM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Engine Light - Thermostat or Cooling Sensor?

2005 Colorado, 127,000 miles, 4 cylinder engine.
Engine light came on yesterday & I went by Autozone to have them do the free diagnostic check.
The guy told me the code it gave indicated either low coolant level (level was fine), a bad cooling sensor or a bad thermostat.
The truck has never seemed to run hot, but I guess if a sensor was bad it probably wouldn't let me know anyway, huh?
How expensive would this be at a garage vs how difficult would it be to do myself?
The last thermostat I replaced was probably on a 68 El Camino, but I have done the throttle body cleaning & replaced spark plugs on my Colorado from how-to info given here.
Any advice appreciated!
texan767 is offline  
Sponsored Links
Advertisement
 
post #2 of 48 (permalink) Old 11-10-2010, 03:53 AM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

Did he tell you what the code was?

I got the p0128 code and it was the thermostat. It was stuck open and did not let the engine reach proper operating temp.


.
DBNissan is offline  
post #3 of 48 (permalink) Old 11-11-2010, 12:16 AM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Re: Engine Light - Thermostat or Cooling Sensor?

No, he just said that's what the code indicated, one of those three possibilities.
For a $40 part, how difficult is changing the thermostat?
I've heard some crazy things, like there is no drain in the radiator...
texan767 is offline  
post #4 of 48 (permalink) Old 11-11-2010, 03:43 AM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

Correct, there is no drain on the cooling system.

It's relatively simple. Raise the truck, remove the driver's side front wheel and the wheel well rubber splash shield. You will then see the lower radiator hose. Follow it to the block and you will find the t-stat housing/neck. Remove the two 10mm bolts then pull it back so you can remove the hose from the neck. You will lose about a quart to half gallon of coolant. Install the hose onto the new t-stat (be sure to line up the line on the hose with the notch on the t-stat housing to insure proper installation), bolt it back on the block and top off with coolant.


.
DBNissan is offline  
post #5 of 48 (permalink) Old 11-11-2010, 01:28 PM
Senior Member
 
Join Date: Jan 2005
Location: Winter Haven, Florida
Posts: 1,116
Re: Engine Light - Thermostat or Cooling Sensor?

Hey, DBNissan, or anyone, really.
I "think" I saw this code come up before when we got hit by a nice cold blast last week. I didn't think anything of it so I just reset it. but I'm pretty sure it was the same P0128 code. During normal driving, my thermostat never reaches the first 1/4 mark. Matter of fact, this whole week in the 50s that temp needle never exceeded the halfway point between the Cold line and the first 1/4 mark line. If it was truly P0128, how long would it take for the CEL to come back on? I haven't had it on for 5-6 days now, and it's been 50's-60's every morning and evening...

It "seems" to me like I'm getting slightly better fuel economy this way...but what are some of the cons of leaving a stuck-open thermostat on?

ALSO, please be advise, I did a flush 2 years ago and filled up with 2 bottles of Redline Water Wetter, topped off the rest with 50/50 GM Coolant. About once a year the reserve drops under the full-cold line by one-finger or so and I just top off again.

It's funny because when I checked it then it was fine and I put it in the correct way in...or at least I think I did...I "think" the spring-mechanism goes facing away from the engine...but honestly I can't remember, I just know however it came out I put it back in the same exactly way.

any advise would be greatly appreciated.

2004 Colorado RegCab ZQ8
I5, 3.42, 5sp
Dynomax SuperTurbo Muffler
Volant CAI w/ RamAir
HPTuners custom tune
200 RWTQ @ 4,200 RPM
207 RWHP @ 5,800 RPM
VortecI5fan is offline  
post #6 of 48 (permalink) Old 11-11-2010, 07:14 PM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

The P0128 code will come on when the PCM detects that the engine does not reach a minimum operating temp within a certain amount of time based on IAT and ambient temp. I noticed on my scangauge that my temp was about 10-15F below the normal range of 195-205F that my truck used to operate in. I too did notice slightly better fuel economy at the beginning. However, the cooler temps will potentially prevent the PCM from switching to closed-loop. When the programming is in open-loop, the engine runs a little richer. That can lead to carbon deposit build-up and a clogged catalytic over an extended period of time. The carbon deposits alone will lower the fuel economy in the long run.

Which spring mechanism are you referring to?


.
DBNissan is offline  
post #7 of 48 (permalink) Old 11-15-2010, 12:30 PM
Senior Member
 
Join Date: Jan 2005
Location: Winter Haven, Florida
Posts: 1,116
Re: Engine Light - Thermostat or Cooling Sensor?

Quote:
Originally Posted by DBNissan
Which spring mechanism are you referring to?
It's been a while so I don't even remember what our thermostat looks like, the "spring" side, or flat-side of the thermostat. Not he round "hub" side. I "think" it was set with the "spring"/"flat" side facing away from the engine...but honestly it's been so long I can't remember.

Last time I had the P0128 was 11/5/2010. So far today 11/15/2010 nothing yet...but I'm still keeping my eye on it for any CELs.

2004 Colorado RegCab ZQ8
I5, 3.42, 5sp
Dynomax SuperTurbo Muffler
Volant CAI w/ RamAir
HPTuners custom tune
200 RWTQ @ 4,200 RPM
207 RWHP @ 5,800 RPM
VortecI5fan is offline  
post #8 of 48 (permalink) Old 11-15-2010, 01:28 PM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

The t-stat can only go in one way. It's integrated into the housing. The housing and t-stat are sold as one unit.




.
DBNissan is offline  
post #9 of 48 (permalink) Old 11-17-2010, 01:36 PM
Senior Member
 
Join Date: Jan 2005
Location: Winter Haven, Florida
Posts: 1,116
Re: Engine Light - Thermostat or Cooling Sensor?

looks like I had it backwards in my head.

What is the part number to this?

So far no CEL yet. Still waiting...

2004 Colorado RegCab ZQ8
I5, 3.42, 5sp
Dynomax SuperTurbo Muffler
Volant CAI w/ RamAir
HPTuners custom tune
200 RWTQ @ 4,200 RPM
207 RWHP @ 5,800 RPM
VortecI5fan is offline  
post #10 of 48 (permalink) Old 12-21-2010, 03:22 PM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Re: Engine Light - Thermostat or Cooling Sensor?

Sorry I took a while to get back, but I'm getting the P0128 code.
From what I read here, lookes like the thermostat.
Any advice on replacing this?
Thanks!
texan767 is offline  
post #11 of 48 (permalink) Old 12-21-2010, 03:29 PM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

You can access the t-stat through the driver's side front wheel well. Remove the wheel and inner splash guard and you can see it to the left. There are two 10mm bolts holding it in. An extension and swivel will help.


.
DBNissan is offline  
post #12 of 48 (permalink) Old 12-23-2010, 02:46 PM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Re: Engine Light - Thermostat or Cooling Sensor?

Ok, broke down & had a garage diagnose it & they are telling me thermosat & fan clutch need to be replaced for $452!
Parts look to be around $100, if I want to do this myself.
Any specialty tools needed or is this something that shouldn't be too hard to do?
texan767 is offline  
post #13 of 48 (permalink) Old 12-23-2010, 06:30 PM
Senior Member
 
Join Date: Apr 2009
Location: Hebron, Indiana
Posts: 2,465
Re: Engine Light - Thermostat or Cooling Sensor?

I put a thermostat in a Collie once and do not remember it being any big deal. Pull the left front wheel inner liner and it is right there. As I remember it was two bolts and one hose clamp.

From your description on Nov 9th you stated that it was not over heating. From that I would go after the sensor before I replaced the fan clutch. The fan clutch is rarely used in cooler weather so a bad clutch should not show up unless you are doing a lot of time sitting at stop lights or a lot of idling. I've not done a Collie fan clutch before but on most other GM vehicles a fan clutch is a fairly simple 15 or 20 minute job.


Drain the cooling system. (It does not have to be completely drained)
Remove upper radiator hose
Disconnect the A/ C hoses from the cooling shroud. (mounted with a clip).
Remove the clips on the left and right of the upper shroud that hold it to the lower shroud.
Remove the upper shroud
Turn the fan clutch hub CCW to remove it from the water pump
Remove the fan and clutch as one unit.

Reassemble everything in the reverse order.
Fill with coolant
Be sure to recheck the coolant level once you have warmed up the engine.

There is a mechanics trick to remove the clutch hub from the water pump. I use a muffler impact gun with a flat end and hit one of the six the flat sides of the nut like area of the hub. I hit it just slightly off center with a short burst and it will spin right off.

If that procedure bothers you then get a strap wrench to hold the water pump end while turning the fan clutch hub with an open end wrench.

From your description I really doubt that you have a bad clutch.

What is your temperature gauge reading when you have this problem?
Does it fail while driving down the highway are does it fail while sitting at traffic signals?

2005 White 2wd Z71 WT
n9cv is offline  
post #14 of 48 (permalink) Old 12-23-2010, 08:38 PM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Re: Engine Light - Thermostat or Cooling Sensor?

The temp gauge never gets above the 1/4 mark, whether I'm driving, idling, or whatever.
From what I gathered here, I thought it was just the thermostat.
With the timing, money laid out at this time of year, etc., I didn't know if I had time to replace before a 300+ mile trip.
A place I called gave me a price of $165 to replace the thermostat.
Of course, onece I got there & they ran their diagnostics, they tell me I also need the fan clutch, jacking that price from $165 top $452.
I just don't trust garages & a good, trustworthy mechanic is verrrrrrry hard to find!
texan767 is offline  
post #15 of 48 (permalink) Old 12-24-2010, 01:03 AM
Senior Member
 
Join Date: Apr 2009
Location: Hebron, Indiana
Posts: 2,465
Re: Engine Light - Thermostat or Cooling Sensor?

That has always been my problem too. Finding a good, trustworthy, and reasonably priced mechanic is very difficult. That is the reason I have resorted to working on cars all of my life. I do not like doing it but I do it because I do not like getting ripped off by over priced parts swappers.

My suggestion (and I am guessing) is to replace the thermostat because it is cheap ($31.00 on Rock Auto) and then see what happens. You should be able to do this yourself. It should 1/2 hour if you are experienced and 1 hour max if you are a novice. Get a big a big pan like a dish pan and put it under the thermostat. Then just loosen the lower hose hose and catch most of the coolant for reuse. Thermostats fail frequently so you have a good chance that is the problem.

Then try replacing the sensor. I have never bought one of these for a Colorado so I do not know what they cost. Rock Auto lists the sensor of an I5 at $11.00 and $26.00. I did not look at AutoZone or NAPA.

Finally go for the fan clutch but in this season (winter) I can not see how the clutch is causing your problem. $97.00 to 113.00 on Rock Auto.

It still bothers me that you are not getting overheating or high temperature indications on the gauge. This tells me that this probably is a sensor problem or thermostat problem and not a fan clutch. The fan clutch is only engaged when the cooling system temperature is over the normal operating range. The clutch is used to force additional air through the radiator to assist in cooling the engine down.

I guessing on everything here. It is difficult diagnosing a vehicle when you do not have it in front of you.

GOOD LUCK

Please let us know what you find.
Shop around. You probably can find the parts cheaper that what I quoted above.

2005 White 2wd Z71 WT
n9cv is offline  
post #16 of 48 (permalink) Old 01-06-2011, 01:39 PM Thread Starter
Member
 
Join Date: Sep 2009
Posts: 74
Re: Engine Light - Thermostat or Cooling Sensor?

As it turns out, my neighbor is a used car dealer & I asked him if he knew a good mechanic & he came though with flying colors.
The guy replaced the thermostat for $60, using my part.
Now temp gauge gets up to & stays at about the half way mark.
No more check engine light, either.
texan767 is offline  
post #17 of 48 (permalink) Old 01-07-2011, 06:19 AM
Senior Member
 
Join Date: Apr 2009
Location: Hebron, Indiana
Posts: 2,465
Re: Engine Light - Thermostat or Cooling Sensor?

Great!

2005 White 2wd Z71 WT
n9cv is offline  
post #18 of 48 (permalink) Old 01-13-2011, 05:04 PM
Senior Member
 
Join Date: Jun 2005
Location: Angier, NC
Posts: 302
Re: Engine Light - Thermostat or Cooling Sensor?

You know, I've been reading about this very issue in different places. For a while now, and especially since moving to NC, I've noticed that my temp is doing the same thing that others are seeing.... Very low temperatures, and very occasionally, the P0128 code. My ScanGauge is reading an operating temp of about 172 F, and the dash gauge barely gets off Cold.
One article I came across mentioned that the coolant may be losing its composition or breaking down. I've got about 145K on the truck and haven't changed the coolant yet! (I know, I know.. Bad owner! In my defense, things have been HELLA busy around here.. getting married, moving, new job, etc tend to take up a ton of one's time!) Well, this weekend, I'm planning on doing a coolant flush.
Has it been decided that replacing the thermostat fixes this issue? I doubt seriously that it's a fan issue. Most of the time, I'm seeing the CEL while doing 60 down a highway, early morning, heading to work! I'll clear it with ScanGauge and it doesn't come back for quite a while.


-Roger

Black Betty is long gone...

'07 Jeep Grand Cherokee Overland (It's got a HEMI!)

GunTotingAmerican #37
CpnBnanaMn is offline  
post #19 of 48 (permalink) Old 01-14-2011, 02:32 AM
CALI-BOSS
 
DBNissan's Avatar
 
Join Date: Aug 2005
Location: Stockton, CA
Posts: 16,808
Re: Engine Light - Thermostat or Cooling Sensor?

It fixed mine.

I did the coolant service hoping that was the cause. I still got the P0128 code. Swapped the t-stat out and truck magically hits the mid-mark on the temp gauge every time now. Scangauge reads 195F - 205F consistently.

Congrats on getting married, Roger!


.
DBNissan is offline  
post #20 of 48 (permalink) Old 01-14-2011, 02:44 AM
Senior Member
 
Join Date: Apr 2009
Location: Hebron, Indiana
Posts: 2,465
Re: Engine Light - Thermostat or Cooling Sensor?

Low engine temperature in my opinion can not be caused by the fan. The thermostat keeps the coolant from circulating until the engine is up to temperature. I do not care what the fan is doing, with no coolant flow the engine will eventually get warm / hot. My engine comes up to operating temp in about 4 miles of driving even when the temperature outside is 0 degrees F.

I'm very biased against the Dexcool antifreeze that GMC uses. That stuff tends to solidify and clog the engine cooling system if air ever gets into the system. I have cleaned up way too many messes caused by air and "Death Cool". It is not quick or fun. This is NOT your problem at the moment as DeathCool causes over heating not over cooling.

Replace the thermostat and while you are at it flush and replace the antifreeze.

Take a look at some of these pictures of Dexcool damage.

http://www.google.com/images?q=dexcool+ ... 24&bih=574

Also research some of the law suits on Dexcool. Just Google Dexcool for more information.

2005 White 2wd Z71 WT
n9cv is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy Colorado & GMC Canyon forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome