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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
I have a 2004 trailblazer with I-6 engine. Truck started to make a jet turbine type noise for about 30 seconds during a cold start (hasn't been driven for a couple of hours). If the truck is started after that no noise is present. I also noticed a bit of a performance hit as the truck seemed to be bogged down. Also it would have a hard time shifting into second during cold start conditions. I changed out the fan clutch assy and the water pump. I started the truck and its still making that noise. I noticed that the truck drives much better now and that the 2nd gear shifting issue looks to be gone. The start-up noise is killing me. Replacement clutch is a BEHR.
 

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i had the same problem..r u getting a code? i just did away with the fan and put an electric one in there. but my check engine light is always on. i was thinking it could have been the harness between the fan clutch and the main harness..i'm checking mine out to see.
 

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Discussion Starter · #3 ·
No I am not getting a code. The original problem also did not produce a code. Does anyone know if its possible to disengage the fan-clutch harness and start the truck in order to isolate the issue?
 

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2003 chevy trailblazer_lt_ext
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For clarification, was your fan making the "jet turbine" sound all the time before replacement? Was the fan obviously hard to turn by hand with the engine off? If your answer is no to either/both of time, Im not sure if you really needed to change out the FC.

You should be able to disconnect the harness and see if it still happens. You will most likely throw a code in the process of the test.

What you describe after the swap sounds pretty much like normal operation compared to mine which also had the FC replaced.
 

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Discussion Starter · #5 ·
GusMan - My original problem was that I get a high pitched noise during start up which lasts for 30-60 seconds. Its not a loud blower type noise it is more like a whirling noise from a turbo. I know this is not normal for the truck as it never did this when I first bought it. I will try to record the sound today when I leave work and post it online.

Just an fyi I only get this noise at a start up when the truck has been sitting for about 3+ hours or so. Also after the initial 30-60 second whirl I never hear it again while driving.
 

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2004 gmc
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I'd guess your current noise after the fan clutch replacement is coming from the idler pulley, which fail often, but they're cheap, cheap to replace since you can get them in the aftermarket parts stores.

But here's some more reading on the fan clutch:

http://forums.trailvoy.com/showthread.php?t=19604

To disable the fan, you can disconnect the harness, or (much easier) pull relay #45 in the front fuse block.
 

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2004 chevy trailblazer_ltz
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Help Mr. Roadie

I'd guess your current noise after the fan clutch replacement is coming from the idler pulley, which fail often, but they're cheap, cheap to replace since you can get them in the aftermarket parts stores.

But here's some more reading on the fan clutch:

http://forums.trailvoy.com/showthread.php?t=19604

To disable the fan, you can disconnect the harness, or (much easier) pull relay #45 in the front fuse block.
Hello
This is Carlos Martinez from Venezuela
In several times I 've wroten about my big problem
I Have not received any lucky comment that really help me

I have the FC repalaced, Complete Cluster Replaced
Iddle speed RPM are crazy as Mother-in-law .Some days 650 some others 950Overheating and FC desengaging happens in Heavy Traffic when crazy (950)
When Normal (650) temperature is just fine no matter Traffic, Drive gear & A/C cooling as a frezzer.
Once you or Mr. Super88 said something about " A bad temperature sensor may PCM confuse and FC will not engage" or something like that:confused:

I would like you to help me with a list of sensors that I just have to check (in Normal & Crazy RPM'S) in order to find out wichone is guilty of this abnormality

I will really appreciate your and any other member help...I'm really worried cause rain season started in my country and heavy traffic with A/C on will be necessary in everyday driving..

Sincerely Carlos Martinez .....:thx

Saludos desde Venezuela.........:tiphat
 

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Discussion Starter · #8 ·
last night I started the truck with the fan clutch disconnected noise is still present. Replaced both idler pulley and tensioner assy. Started it up and noise is still present. Noticed that noise seems to be coming from lower drivers side. Wondering if issue could be with A/C compressor or even starter assy. I have seen threads regarding the A/C compressor bearing going bad. Could that be the issue? How easy is it to replace this part?
 

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Mr. Roadie !!!!I found the connector!!!!!!

:):):):):):)
:crackup::crackup::crackup:
:woot::woot::woot::woot:
:woohoo::eek::woohoo:
:laugh::laugh::laugh:
Mr. Roadie please help me to identify where does the 2 wire connector (just left hand side of the PCM go to?
This is the one I have not test in normal iddle speed RPM (650), Yesterday iddle speed was just fine, and I unplug the connector I just said , and 3 seconds later iddle speed rise to 950 RPM, temperature start to rise up , Fan Clutch desengage (As I described in previous posts) after 15 minutes I plug it back 3 seconds later RPM down to 650 , fan start running tremendous and , of course, temperature also went down !!!!!! So this is it !!! but What does this connector go to? I think goes down the engine between the alternator and the left side of the block engine, I couldn't see more... Do you have any Idea ??? AMIGO ???

I really appreciate your help, I've been trougth this for 6 months...

Hope to hear from you soon !!!

Saludos desde Venezuela

P.S. Sorry about my english grammar i...:no:
 

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2004 gmc
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Very interesting. That's the coolant temp sensor. Just above the thermostat. Explains all your problems, since if the PCM thinks the engine's too cool, it will raise the idle RPM. This is a chart from the PCM programming tables.



Your excitement is very obvious!!!! Congratulations!
 

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Thank you very much Mr.Roadiefor this information

Very interesting. That's the coolant temp sensor. Just above the thermostat. Explains all your problems, since if the PCM thinks the engine's too cool, it will raise the idle RPM. This is a chart from the PCM programming tables.



Your excitement is very obvious!!!! Congratulations!
It is too difficult to replace that?
I wiil get the part, so I need some tips (If you have) to replace the damn coolant temp sensor by myself
I know some mechanics since I was a boy ( 12 years old) starting with my Dad '67 Ford Mustang
Now I'm 44 and I have replaced the complete cluster and the Fan clutch by myself with no special tools , I like to perform my own special tools...

Thanks again for your time and explanations,

You really are a good fellow....:thx

Saludos nuevamente desde Venezuela amigo Rodie !!:tiphat
 

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i've been on here checking stuff out and it's awesome what you all have done..being said that i have jinked myself i think..lol looking at everyone else's problems and thinking thank god i dont. well now i do! lol

i have a 2002 tb lt 4x4, live in south ga and is hot as balls (heat index of 118)
running my truck in town w/ac on and noticed my temp got up almost to the 3/4 mark then goes down.

i did my electric fan(bought at auto zone universal one) some time ago and has been fine.

could it just be the weather or is something wrong? i changed it out cause i got a code saying it was bad but when removing it noticed the harness between the clutch and main harness looked bad,broke clip and worn wires(like something rubbed them) but went ahead and changed it to electric for better response and mileage.

any help would be great and thanks ahead of time and for having this sight..i'm frigging addicted!!
 

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Bad News Mr. Roadie

Very interesting. That's the coolant temp sensor. Just above the thermostat. Explains all your problems, since if the PCM thinks the engine's too cool, it will raise the idle RPM. This is a chart from the PCM programming tables.



Your excitement is very obvious!!!! Congratulations!
Good Morning Sir.
I have to tell you How dissapointed am I.:duh:
Yesterday Crazy RPM (950) begun as I was driving home (about 50 MPH)
Temperature started to rise up, well, I got home, opened the hood, (engine running in Park gear) unplugged the coolant temp sensor and nothing happened with RPM, but temp gauge drops to Zero, Do this mean that the damn sensor is working Ok? Because I plugged back (same 950RPM was in tachometer) and temp gauge worked perfect?
I try different impedances between the two wires in the male connector of the coolant temp sensor (when was unplugged) and nothing varies in iddle speed revolutions...
Is there any other sensor that may be bad and makes PCM to rise up the RPM at iddle speed (no matter gear position or A/C on or off)

I'm really desperate with this issue, Don't know what else can I do:(

Hope to hear from tyu or other member who can give me a hand with this:confused:


I will appreciate so much somebody help:sadcry:

Saludos

Carlos Martinez desde Venezuela
 

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2004 chevy trailblazer_ls_ext
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All of you guys might need to get your PCM re-calibrated with the latest firmware... when installing the most recent fan clutch, if you haven't already had the revised firmware installed for better FC control, then I would recommend that road, why? Because it's the cheapest route, and will most likely prevent future headaches.... now on the overheating issue, there is an updated firmware that's available, which I don't have installed currently, my truck temp gauge as well creeps up in 90+ weather with the A/C on ... I installed an electric fan for this particular scenario, cuz the dealer was clueless as to what could be the problem... well the updated firmware that is suppose to take care of this problem was released many months after that last visit to the dealer to address the overheating issue... they concluded that it was within specs... now I am going to have to cough up 100 bucks to get the latest firmware...
 

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Knblazer

You mention that your temp goes up when you have 90 degrees + with the AC on. I have recently noticed that my temp gage goes up midway between 210 and max when climbing a long hill here in southern CA with the outside temp. near 100. Is that normal?? I never noticed it going up at all during the winter months. I just bought our 2004 Trailblazer 4.2L this winter so I have no way of knowing what it did with the prior owner. Once I reach the top of the hill the temp goes back down.

This is my first post here on this forum. I did a search but did not find an answer to my problem (?)
 

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You mention that your temp goes up when you have 90 degrees + with the AC on. I have recently noticed that my temp gage goes up midway between 210 and max when climbing a long hill here in southern CA with the outside temp. near 100. Is that normal?? I never noticed it going up at all during the winter months. I just bought our 2004 Trailblazer 4.2L this winter so I have no way of knowing what it did with the prior owner. Once I reach the top of the hill the temp goes back down.

This is my first post here on this forum. I did a search but did not find an answer to my problem (?)
No this is not normal. I bought my 05 EXT new. I often drive from Southern Ca. to various places in Arizona. Going up the long hills (70-75 MPH) on I-8 even in 110 degree heat with both a/cs running - I never seen my temp gauge go more than one "notch" above the 210.

I would start with the cheap stuff first - thermostat and maybe hoses
 

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To disable the fan, you can disconnect the harness, or (much easier) pull relay #45 in the front fuse block.
I'm pretty sure my AC clutch bearings are going, but to rule out the fan clutch, I pulled relay 45 and the fan still spun (and no change in the noise). Shouldn't the fan not spin at all if relay 45 is pulled?
 

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2003 gmc envoy_slt
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The fan will spin from parasitic friction from the water pump. But, you should be able to CAREFULLY stop it from spinning to see if the noise stops when the fan stops.
 
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