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I have an 05 trailblazer that started knocking thought it…

Customer Question
I have an 05...

I have an 05 trailblazer that started knocking thought it was the alternator changed that stopped for a day but now it dies when i start it am not on the throttle which i assume is the fuel pump

Mechanic's Assistant: Where exactly do you think the noise is coming from? And how long has this been going on?

Sounds like my valve cover but not sure if its my fan clutch front of the motor

Mechanic's Assistant: Are you fixing your Trailblazer yourself? What have you tried so far?

Just did an oil change myself and yes i do all my car work been working on cars for 13 years when they need work

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Nonot that i can think of

Submitted: 7 months ago.Category: Chevy
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Answered in 2 minutes by:
12/21/2017
Chevy Mechanic: Dan, Technician replied 7 months ago
Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 26,017
Experience: Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Chevy Mechanic: Dan, Technician replied 7 months ago

Does it run good other then stalling with foot off the gas? Is check engine light on? Thanks.

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Customer reply replied 7 months ago
it did run really well until on my way home from work last friday the light was on but no longer is after i changed the oil
Chevy Mechanic: Dan, Technician replied 7 months ago

It sounds like you may just have a dirty throttle body. As the throttle body gets dirty the computer slowly learns to adjust to compensate, when battery is disconnected the computer is reset so is not longer adapted to the dirty throttle body. You can get throttle body cleaner from parts store, spray onto a rag, then wipe out throttle bore and throttle plate. Let me know if you have more questions or if there is anything else I can do to help. Thanks.

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Customer reply replied 7 months ago
im curious as to if its my fan clutch or water pump but it never overheated
Chevy Mechanic: Dan, Technician replied 7 months ago

Neither of those would cause it to stall but may cause noise, is it still making the knocking noise?

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Customer reply replied 7 months ago
but that doesnt explain the knocking im hearing around the front of my motor im not second guessing you im just saying that it is knocking on the front of my motor and thats really what i needed answered i was going to clean the tb after i installed the fuel pump
Chevy Mechanic: Dan, Technician replied 7 months ago

I do think the knocking most likely means the fan is the problem. Start by removing the drive belt to see if problem stops if so I'd suspect tensioner but you can then see if each pulley turns like it should or has any play. If it still makes the noise with belt removed next step would be to remove fan to see if noise stops or if there is play in fan assembly if so replace. If noise happens without fan connected or drive belt on then this would point toward internal engine problem such as timing chain. Let me know if you have questions, thanks.

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Customer reply replied 7 months ago
well i toook the belt off the day before yesterday and replaced my alternator because it was rattling when i spun it with just my hand just a bit but i know that im not spinning near as fast as the belt would so i took it off and started the vehicle no noise put the new alternator in reassembled everything then started it with no noise started it today because was going to remove fuel relay to get the pressure out of the lines and replace the pump then comes this noise again
Chevy Mechanic: Dan, Technician replied 7 months ago

I'd try to pull belt again while noise is happening, if noise seems to stop every time belt is removed then problem is something that is being turned by the belt. A stethoscope might help figure out where the noise is coming from too. Let me know if you have questions, thanks

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Customer reply replied 7 months ago
could it be the water pump? i mean this sounds like its coming from motor or from somewhere under the valve cover i mean my a/c did lose number 4 power about 6 months ago so maybe fan clutch, water pump, maybe a valve, or just the tensioner
Customer reply replied 7 months ago
i kinda wanted to get this done before it freezes tonight so im not out in the freezing cold busting my hands up
Customer reply replied 7 months ago
https://www.youtube.com/watch?v=QDTyTuIxaIE this is what it sounds like
Chevy Mechanic: Dan, Technician replied 7 months ago

It could be the water pump but most common thing to cause the noise is the tensioner. That noise sounds like a internal engine problem so I'd check again to see if problem happens with belt off, if not then next step is checking each pulley for play or using a stethoscope. Let me know if you have questions, thanks.

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Customer reply replied 7 months ago
did you watch the video that i sent?
Chevy Mechanic: Dan, Technician replied 7 months ago

I did, sounded like a internal engine problem such as a worn bearing but if noise isn't happening with belt removed then that would mean engine is fine and something that belt is turning is making the noise.

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Customer reply replied 7 months ago
ok well ill go take the belt off real quick and start it and be right back if it is a worn bearing should i just take it to a shop to have them do it?
Chevy Mechanic: Dan, Technician replied 7 months ago

There shouldn't be any play in any of the pulleys, if water pump or tensioner was loose enough to make that noise then I'd think there would be a little play in it. If bearing is problem you are looking at engine replacement so lets hope noise stops when belt is removed. Keep me updated, thanks.

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Customer reply replied 7 months ago
well looks like i need a new motor but it was weird when i started it it didnt have any trouble staying idled
Customer reply replied 7 months ago
without me pushing on the throttle
Chevy Mechanic: Dan, Technician replied 7 months ago

The worn bearings usually won't effect how it runs until it completely blows up which would probably happen within another 100 miles of driving. Sorry about the bad news, you can look at www.car-parts.com for used engines in your area and I'd call at least 3 different places for quotes. It is about a 19 hour job to replace engine so you are probably looking at around $3000 total depending on where you go. Since it costs so much your better option may be selling vehicle as is and buying something else. Let me know if you have questions, thanks.

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Customer reply replied 7 months ago
how much of a difference in part would it be to switch it to the v8 ss motor like what all will need to be changed
Customer reply replied 7 months ago
also 3000 is with the motor or just labor?
Chevy Mechanic: Dan, Technician replied 7 months ago

$3000 should be with the motor and switching to the V8 would be a big job as the computer, wiring, and transmission are all different. Let me know if you have questions, thanks.

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Customer reply replied 7 months ago
like 5 grand or closer to 10 cause isnt my motor inline 6?
Chevy Mechanic: Dan, Technician replied 7 months ago

Yes yours is the inline6 and about $3000 total. Around $2000 labor and $1000 for a used engine, price might go up to $4000 depending on cost of engine and what type of quotes you get. Most shops charge around $100 a hour and it is a 19 hour job. So then cost of oil, coolant, and replacement engine.

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Customer reply replied 7 months ago
well thanks for all your help and merry christmas
Chevy Mechanic: Dan, Technician replied 7 months ago

No problem, I'm happy to help. Thanks again and have a Merry Christmas.

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