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2003 olds bravada
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48 Posts
Discussion Starter · #1 ·
I am having a heating issue with my 03 Bravada 4.2

It started about 4 weeks ago. I noticed that the temperature gauge showed between the 210 and the next major hash mark. The truck always, always runs at 210 for the last 6 years. I thought it was an isolated episode, however over the past week the temperature is now going above 210 when I come home from work in the evening. The temperature stays at 210 in the morning on the way to work.

I replaced the thermostat on Sunday because its a cheap part. No improvement. I was going on a trip so I took the truck to the dealer on Tuesday to get it fixed. After 3-4 hours they didnt have an answer. Said yeah it was running hot but they couldnt find a reason. They said I should be fine to go on my trip today. I was less them impressed.

So I looked last night on the forums for several hours. I found other folks that were having issues but there wasnt a solution posted for most of the problems. The list of potential culprits was waterpump, bad gauge, bad temperature sensor, clogged coolant or bad fan clutch. I have 93,000 miles on her just FYI.

So today I drove 750 miles. Temperature was perfect at 210 when I am running at highway speeds (40 mph to 80) going up hills, running the AC on high, everything just as how it has been the last 6 years. However when I pull into the rest stops, gas stations or go city speeds the temperature creeps up to the higher ranges like it was doing in my day to day life the last few weeks in the afternoon.

I got to thinking and I also have noted a big puddle of water in the morning under the AC area of the car. I dont recall seeing water in the morning in the past. Nothing like 750 miles to make you ponder stuff. I have also heard the make the air plane noised early in the AM when I pull out of the driveway but it seems to go away after a block. I have heard the engine do the ticking noise for the past 3 years (just thought that was normal).

So now I am thinking that my problem is a crappy fan clutch that isnt moving enough air when I am tooling around town at lower speeds. Am I correct? Also why wasnt the tech able to diagnose this?

Should I get this fixed ASAP at the dealer here or can I wait a week and "try" to do it at home? I know this platform of vehicles has fan clutch issues and to my knowledge mine has never been changed.
 

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8,781 Posts
It does have the symptoms of FC failure.. has the CEL come on at any time??

Did you replace the stat with an OEM one of the same temperature rating?

FC removal and install isn't hard per say.. just time consuming


You could go to an Autozone or the like and see if they can scan for codes (may be one hidden that hasnt tripped the light yet :undecided)
 

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2004 gmc
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26,181 Posts
The tech is a goof. At idle, the engine barely generates enough heat to need the fan running, but out in traffic, stop and go, it needs the fan to be running. He should have taken it for a ride with the scan tool and see if the commanded fan RPM was ever sent up to 1000 RPM or so, or if the actual fan RPM was not equal to the commanded RPM. A mismatch should throw a code after a while, but we've certainly heard of enough fan clutch failures without codes being set.

You can try to catch it in the act of overheating in traffic, then pull over with the temp gauge above 210, and use a rag (carefully) to try to stop the edge of the fan from rotating. If it stops easily, it's the clutch. You might also see that it's not spinning fast at all, and with the gauge at 210-230, it should be locked to the engine RPM. If you can have somebody in the car press lightly on the pedal to get the RPM to 1000-1200, the fan clutch should speed up with the engine and blow hot air like a banshee. If it's wimpy, replace it.

2002-2005 were the bad years for the original design clutch, and they are having a HUGE failure rate as the years go by. Your ticking is normal, as is the early morning start-up loud noise. But I'd certainly buy a replacement, and get prepared to do the swap, and try to not get trapped in traffic jams in the meantime.
 

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2005 chevy trailblazer_lt
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29 Posts
I'm having the same problem. Changed the thermostat no change. Noticed the clutch fan barely moving, changed it for a Dorman model temperature back to normal but it keeps throwing a P0526 fan speed circuit sensor. What do I do now. Sorry about hijacking your thread.:confused:
 

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2003 gmc envoy_slt
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7,190 Posts
Those are the same symptoms I'm experiencing. I have a FC ready to replace my original. I only have 38,xxx miles, but I'm changing the water pump at the same time.:m2:
 

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2007 chevy trailblazer_ss_1ss
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1,852 Posts
Sounds like a fan clutch to me. When you're going at highway speeds, you're getting enough airflow through the radiator that it doesn't much matter what the fan clutch is doing. I would highly recommend getting a GM fan clutch because the cheap auto parts store clutches are made on the old design. You can get them on eBay for cheap, I bought a brand new one sealed in the box for my truck for $130.

I see you've already used the Dorman one. Well, does their's come with the wiring harness from the clutch itself to the edge of the fan shroud? If not, you can buy just the wiring harness (I believe there was a recall or something on those at one point).
 

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2003 olds bravada
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48 Posts
Discussion Starter · #8 ·
TYTYTY for the replies.

I will play with it tomorrow in the act of over heating.

Ill keep you updated if anything wonky happens. Also sending a note to my service advisor asking him if the tech did as you described.
 

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2005 chevy trailblazer_ls
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TYTYTY for the replies.

I will play with it tomorrow in the act of over heating.

Ill keep you updated if anything wonky happens. Also sending a note to my service advisor asking him if the tech did as you described.
Have your coolant chemistry checked for carbon dioxide. If it's present, the problem is a leak from the combustion chamber (head gasket leak most likely). No CO2 in the coolant, most likely the fan clutch. Also check the intake hose to see if it's collapsing. That will cause overheating as well.
 

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2003 olds bravada
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48 Posts
Discussion Starter · #10 ·
Update

So I drove the Bravada home from the trip. It did the same thing as on the way up. Temp at 205 or whatever it is just below the 210 mark on most of the trip. There was one section in Wyoming where the ambient air temp was about 87-89 degrees and the engine temp was going above the 210 mark (maybe 215-220) my speed was 75mph and some rolling hills. Then we hit a rain storm, air temp dropped to 70 degrees and then engine temp went back to the sub 210. I thought that was weird.

I changed the fan clutch with a new Behr clutch and put in a new water pump. I did it myself (ty Trailvoy for the articles) last Wed. I took the Bravada for a drive after I changed it out. Ambient air temp was 95 degrees that day. The engine temp seemed stable at sub 210 for about 15 mins then it went up to about 225 for the rest of my errands.

The next morning I put some more DexCool into the system reserve tank to top off the little bit that was still missing after doing the water pump change. The DexCool level has been fine since then. I also took the cap of the radiator to look for bubbles as the engine was running. I didn't see any bubbles. The radiator cap looks fine no oil on it. I looked at my engine oil dipstick and the oil looks fine not whiteness to it. I changed my oil last month and it looked fine then too.

So I am not sure if my problem is fixed. I have noticed in the afternoon on the way home from work, 25 mile commute 1/2 city and 1/2 65mph highway, my engine temp creeps up to about the 215-220 mark about 15 minutes into the drive if the ambient air temp is over 85 degrees. When the air temp is cooler then that the engine temp seems fine.

I did some thinking and I also changed my Serpentine belt before any of these problems started to happen. I used a gatorback belt, the one indicated for my vehicle not the EXT. I am wondering if the belt is the cause of my problems. I have had the belt on and off several times since due to the thermostat change and waterpump/fanclutch change. The belt goes on fine doesnt seem loose or too tight.

So at this point I am thinking that I might have a head gasket problem maybe a bad sensor or gauge or maybe my serpentine belt is doing something screwy or possible hose collapsing (they looked fine when I did the other work).

What do you guys think? I sent an email to the dealer before I changed my fan clutch and water pump asking what the Tech had ruled out 100% and why he couldnt figure out a possible problem. Of course no response from the dealer.
 

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2005 chevy trailblazer_ls
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Have your coolant chemistry checked for carbon dioxide. If it's present, the problem is a leak from the combustion chamber (head gasket leak most likely). No CO2 in the coolant, most likely the fan clutch. Also check the intake hose to see if it's collapsing. That will cause overheating as well.
Did you have the coolant chemistry checked for carbon dioxide? That's how my dealer found my head gasket leak.
 

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2003 olds bravada
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48 Posts
Discussion Starter · #12 ·
Did you have the coolant chemistry checked for carbon dioxide? That's how my dealer found my head gasket leak.
I haven't gone back to the dealer yet. I was hopeing that the fan clutch/water pump change would do the job. I might have to get the coolant chemistry evaluated but I am less then thrilled with the dealer atm. I think when I looked at my coolant for bubbles I did that incorrectly. I didnt let the engine get warmed up to normal operating temp. Ill do that part on Wednesday this week or maybe tonight if the engine cools down enough before I go to bed.

And just to answer a previous question the thermostat I put in was an OEM same temp nothing special just a GM thermostat.
 

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2005 chevy trailblazer_ls
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I haven't gone back to the dealer yet. I was hopeing that the fan clutch/water pump change would do the job. I might have to get the coolant chemistry evaluated but I am less then thrilled with the dealer atm. I think when I looked at my coolant for bubbles I did that incorrectly. I didnt let the engine get warmed up to normal operating temp. Ill do that part on Wednesday this week or maybe tonight if the engine cools down enough before I go to bed.

And just to answer a previous question the thermostat I put in was an OEM same temp nothing special just a GM thermostat.
I understand your frustration with the dealer. Are there any reputable radiator shops in your area? They should be able to check the coolant chemistry as well. A reputable shop wouldn't want to sell you a radiator and then find out the problem was something other than the radiator. They would do the diagnostic analysis first.
 

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2003 olds bravada
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48 Posts
Discussion Starter · #15 ·
Hi,

I have some info for you to check.

Check posting # 18 in this link:

http://forums.trailvoy.com/showthread.php?t=45203&page=2

Please refer back to us with the news.
Maybe the coolant sensor. Easy enough to change out when I do the hoses. Then if thats not the fix its to the shop to get the coolant analyzed for CO2. I am in no hurry to find out its the Head Gasket as I don't really want to drop $1200 for it but I do want to know whats up with the girl. Maybe some new shiny tires would make her feel better and get rid of her fever. That or some more cowbell.

Thx for the replies.
 

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2003 gmc envoy_slt_xl
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270 Posts
For head gasket leak.... This works great. Bars head gasket block seal. Has fiber glass and copper to seal leaks.
But under stand that if the leak is real bad. The only thing that will fix it will be to pull the head.

http://www.barsproducts.com/1109.htm
You can use such sealants incase there's loss of coolant only. Otherwise, how is it going to reach the crack?
I tried a similar brand on a Nissan in 1998 that used to bubble air out from the rad, and followed the instructions literally. It worked like magic. Bubbles and overheating disappeared. It was a successful cheap remedy for an expensive repair.
 

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2003 olds bravada
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48 Posts
Discussion Starter · #19 ·
Threw a Code Today

I went into the mountains today to go hiking and got a code to throw after an hour into the drive. Engine Temp was normal throughout the whole drive, steep inclines at 70mph.

So the Code was P0495 according to the guys at autozone.
1. Open or Short Circuit Condition
2. Cooling Fan Relay Fault
3. Failed Cooling Fan Clutch

I put in a new clutch and water pump last week. Do you think the relay is bad? Or do I have a bad replacement clutch. The clutch was a Behr of the current item number.

I am going to go take a look at the clutch's interface and make sure it is snug. Otherwise I am not too sure what to fix. I also thought I would just reset the code and see what happens.

To be honest I was hoping the code would say my temp sensor sucks. Would have made my life easy.
 
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