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Chevrolet TrailBlazer Engine and Performance Problems

03 trailblazer started with loud engine roar after thermostat replacement , no other signs or dash codes.Noise starts at 25 mph and on highway constant .Any ideas ?Similar problems, answers!


  • burdawgburdawg Posts: 1,521
    Sounds like the fan clutch has failed or is not connected right. It's viscous on the TB and needs the control line connected.
  • Mine made a similar noise. Turned out to be the pulley on the A/C compressor. Does it change pitch when you turn the A/C on, then thats it. I changed the fan clutch and the idle pulley before I found the right problem. New compressor is $600 new and $200 used at the junkyard. Good Luck
  • Could this be related to the thermostat replacement that was done?And where is the control line located ?
  • burdawgburdawg Posts: 1,521
    Hard for me to say if it's related or not. Depends on what was removed to get at the thermostat.
    If memory serves, the control cable for the fan clutch runs horizontal along the drivers side of the rear of the radiator, along a plastic boss that supports the whole assembly. If you can see it (I don't recall how much is visible) then maybe you can verify if it's connected.
  • burdawgburdawg Posts: 1,521
    Minor update. The wiring runs at about a 45 angle from the top right of the shroud (assuming your standing in front of the car looking down at the top of the radiator/shroud) between the fan and the radiator. It runs in kind of a conduit. The top connector is on the top right of the shroud from the same view.
  • Thanks for the updated info I checked connection and it is secure,I guess its time to visit the dealer. Thermostat at 55 K $297 ,strange sound at 56 K priceless!!!
  • Second thought,what could happen if I wait for 500 more miles before taking it in ?The fan clutch won't seize or could it. Thanks
  • Hi, I've been reading through your forums looking for a solution to my big problem - our 2002 Trailblazer with 85,000 miles and regular maintenance basically blew up last week with no warning from the gauges. The dealer took apart the engine (I had found the cylinder recall online), but says a blown head gasket caused the problem. We already had the head gasket replaced at 36,000 miles, that time with bells and lights and everything flashing and dinging...this time, NO warning. Any ideas? We already have calls into GMC and are talking with someone who is nice so far...this is going to be over $6000 - Merry Christmas
  • dpratldpratl Posts: 2
    pickup41 -

    Any update on your TB. I'm having the same problem as you. I recently had the thermostat replaced and noticed a roar from the engine as well. I hear and feel the roar when I accelerate hard, like when I'm merging onto the expressway.

    Prior to having the thermostat repalced I had no problems (105k miles).

    Looks like a trip back to the dealer.
  • johnny83johnny83 Posts: 2
    I have an 05 tb with the I6. When I turn on the air or heat it surges almost like it is idled too low. The mechanic said it sounded like the compressor trying to lock up but I was woundering if it could be a idle sensor or something?
  • Can someone tell me if the 2002 trailblazer 6 cylinder clutch fan has one with no electrical connections. I seem to be finding clutch fans on the net with the electrical connections attached. Hubby says the clutch fan runs off the motor with no electrical wires. Does anyone know what the part number would be. I'm confused and looking for this clutch fan.
  • burdawgburdawg Posts: 1,521
    The fan clutch on the I6 engine is electrically controlled, so they will all have a connection. This is done to more tightly control the operation of the large cooling fan and reduce the amount of drag put on the engine by the fan when it's not needed. The end result is better fuel mileage which is of course mandated by the federal government.
  • When the new one arrived, it is stiff when trying to turn it, just like the one one the truck. Is is suppose to be stiff (not turn freely).
  • Got it in within a half hour. Bought one off ebay new for $120.00 with life time warranty.
  • i have a 2003 TB. there is knocking in my engine that gets louder as i press the gas pedal. i still have oil pressure but this noise persist as if i might need a new motor. some other problems that i have been having is my speed meter works when it wants to sometimes i slow down and it does not drop to zero it will drop to about 25 or 30mph. i also can turned the key to crank it and it won't crank it will just start malfunctioning. guages start to jump and my locks start to loc and unlock can anyone tell me any solutions to the problems i have with my 2003 trailblazer. also when i turn my air on the truck dies as if it was not idle up enough.
  • welleswelles Posts: 1
    How do you change spark plugs on a 2005 trailblazer?
  • rpowersrpowers Posts: 24
    I have a 2005 TB with 21000 miles on it. When started in the mornings it seems to have an engine miss for a mile or two - almost like an old carborated engine with a choke sticking. I also don't feel all the power everyone talks about with this in-line six engine. It feels pretty peppy first thing in the morning - but most times it is a slug. Does anyone else have this experience?
  • glo4glo4 Posts: 1
    I have a 2003 TB EXT V8 that is in for a tune up, and changing fluids for 4 wheel drive and transmission. The shop is telling me a couple things I feel the need to check out. I understand that the fluids are pretty expensive. OK But the original quote for everything was around $600. Then the shop called and said that all the wires are breaking as they are taking caps off to get to the plugs. Add another $200 for new wires. Now they are saying that the 8th spark plug is stuck, giving it the weekend to soak and will try again Monday. My vehicle has 122K miles and has been very well taken care of (I thought). Can someone confirm that this sounds right. At least the original $600. I was figuring a tune-up would cost around $200. It's at the dealership that I bought it at and they are the only ones to ever do any work on it. (Oh, and he showed me the broken wires, they were broken about 6-8 inches up from the cap - is that right?) Need some advice anyone!
  • doub05doub05 Posts: 1
    I have a 2002 lt ext v6. The problem I'm having is, when I turn a corner or come to a stop for a while(traffic light), the vehicle acts as if it is going to shut off. It loses a lot of power. I took it in to be serviced and they said it was the fuel pump. Well that has been replaced 3 times already. Anyone have any Idea what the problem could be?
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