This is a replica of a thread that Moderator IffyG wrote on NAIOA. I thought it was a great idea and decided to copy him. He is awesome and this is a great guide to check.

What are common problems to check for before buying a Monte Carlo? How about things to keep an eye on after you have already bought one? Here is a handy list of problems, how to fix them and photos of what to look for if applicable. This list was generated from problems I have experienced over 8 years with my 2002 Chevrolet Monte Carlo that have also been experienced by more than a handful of other members over the years. If you feel I have missed something please let me know and I can update this post.

This list isn’t designed to scare people off, rather it is to make you aware of the common issues found in these vehicles. As said by another member of the forum when I went off on one of these lists before “not all cars will see every issue on the list, but … everybody will probably have one or two. Unlucky people might rack them all up.”

Problem: My climate control only works on settings some settings.
Likely cause: Bad blower motor resistor (2000-2003 Impala and Monte Carlo)
Solution: Replace the blower motor resistor. http://www.naioa.com/v2/modules.php?...wtopic&t=40232
Prevention: nothing

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Problem: I have coolant running down the passenger side of my engine (L36)
Likely cause: Broken coolant elbows
Solution: http://www.naioa.com/v2/modules.php?...wtopic&t=17376
Prevention: replace the elbows anytime you take them off, as they frequently break

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Problem: My headlights don’t work or my high beams won’t stay on
Like cause: Bad multifunction switch (MFS)
Temporary solution: Jiggle the MFS and you should be able to get the lights to work again. I stress that this is a temporary solution and should only be used to get the lights back on to drive somewhere to get it fixed.
Permanent solution: Replace the MFS (I advise against junkyard replacements for this repair).
Prevention: nothing

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Problem: Oil looks like a milkshake or mysterious oil or coolant loss

Likely problem: Lower intake manifold gaskets (LIM) leaking allowing oil and coolant to mix in the engine
Solution: Replace the LIM gaskets.
Articles - NAIOA
Prevention: Change the cheap Nylon gasket to the new revised GM aluminum gasket before you experience any problems. This will allow you to avoid scooping coolant/oil mess from the engine.

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Problem: Oil is leaking from under the valve covers
Cause: Bad valve cover gaskets
Solution: Replace valve cover gaskets

Prevention: Change the gaskets before they fail

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Problem: I’m experiencing seemingly unrelated electrical problems in the vehicle. This can manifest and power locks that don’t work, parasitic draws that kill your battery while you are away from the car, a radio and instrument cluster that won’t turn off. Problem may be exacerbated by high temperatures
Cause: Bad BCM
Solution: Replace BCM (need to find a shop that has a Tech 2 to program the new BCM to match the vehicle). Do not purchase a used BCM, these are programmable once and cannot be used in another vehicle easily.
Prevention: Avoid jump starting the vehicle as this might kill the BCM

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Problem: My transmission is acting strangely
Cause: Could be any of the intrinsic flaws with the 4T65e transmission. Read more here: 4T65E Common Problems Select items in the drop down menu of 4T65E problems to learn more about components with high failure rates
Solution: Replace affected components and have the builder install a Sonnax Sure Cure kit.
Prevention: Change transmission fluid more frequently than the recommended interval. I go no more than 30k on the fluid. If the fluid has been neglected, you might be better off leaving it as changing it could result in the transmission failing in short order

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Problem: Transmission fluid seeping out of ends of cooler lines
Cause: Poorly designed transmission cooler lines
Solution: Replace transmission cooler lines as soon as you notice the seepage. I noticed mine and didn't get them replaced quickly enough and they starting shooting trans fluid up towards the hoodliner.

Prevention: nothing

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Problem: my turn signals don’t work
Cause: Bad hazard switch
Temporary Solution: bang on the dashboard near the hazard switch to see if the turn signals work again.
Permanent Solution: Replace the hazard switch
Prevention: nothing

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Problem: Grinding noises while turning, random activation of traction control, service traction system light on etc
Cause: Bad wheel hub
Solution: If the problem is grinding, the wheel bearing is shot and the entire unit must be replaced. For the other issues, visit a shop that can read ABS codes to determine which hub needs to be replaced. Timken hubs are pretty much the only cost effective option. Also check the wiring harnesses running to the hub as they can break/wear away to the point that they can cause this problem. In addition, it could also just be a disconnected / dirty connector. Clean the connector and plug it back together can fix it. There is also a ground near the airbox that gets dirty and can screw up the ABS computer.
http://www.naioa.com/v2/modules.php?...wtopic&t=26477
Tip:To help determine the problem wheel hub, if you turn to the left and the wheel noise starts, it's the right bearing. Could also be stated, if you turn to the right and the noise goes away, it's the right bearing (but most people think about when the noise starts).
Prevention: nothing

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Problem: My gauges aren’t operating properly (inoperative, max out, stay at zero, bounce around)
Cause: Bad stepper motor
Solution: If you are handy with soldering you can buy the stepper motors cheaply on eBay. If not BBEngineering Impala / Monte Carlo Products for cluster repair services.
Prevention: nothing

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Problem: My fuel level doesn’t read accurately (often either full or empty)
Cause: Bad fuel level sender
Solution: Replace fuel level sender. If you have an fuel tank access door in the trunk the job isn’t too bad. If you don’t, you have to drop the tank. 2001 Impala How To
Prevention: nothing

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Problem: Grinding noises while turning coming from the steering column. Possibly feeling vibrations in the
Cause: poorly designed intermediate steering shaft installed from the factory
Solution: lube the intermediate steering shaft. Intermediate Steering Shaft Easy Fix - Forums - NAIOA
Prevention: frequently lube the ISS. I usually do mine at each oil change.

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Problem: Lack of power, MIL light on, might feel like the transmission won't shift out of first
Cause: Plugged catalytic convertor (2001 and 2002 models are especially prone to this problem)
Solution: Replace the catalytic converter. OEM units are pricey, so aftermarket is the way to go, but you will need to find a solution to the P0420 code that most aftermarket cats will throw. One possible solution is a tuned PCM that deletes the codes related to the post cat oxygen sensor.
http://www.naioa.com/v2/modules.php?...wtopic&t=21966
Prevention: nothing

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Problem: Pulsing/shaking under braking
Cause: Warped rotors.
Solution: Replace with a quality aftermarket rotor and this problem should go away. After going through several sets of OEM rotors, I switched to Centric and haven't warped a set since.
Prevention: avoid getting rotors wet while hot, avoid hard braking and then holding the pads on the rotors

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Problem: Security light is on while driving or the car will not start
Likely cause: Something in the passlock system isn’t functioning properly
Solution: Replace the ignition cylinder.
Prevention: nothing

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Problem: Water in passenger cabin under the blower motor
Cause: The cheap weather stripping under the cowl has slipped off.
Solution: http://www.naioa.com/v2/modules.php?...wtopic&t=31094

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Problem: My windows don’t always work when I press the switch
Cause: Dirty contacts in the switch.
Solution: Take apart the switch and clean the contacts. http://www.naioa.com/v2/modules.php?...wtopic&t=14592 Keep in mind this may not work and you might have to buy a new switch to resolve the issue.
Prevention: nothing

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Problem: my low coolant light is on even through there is no air in the system and there is plenty of coolant in the reserve bottle
Cause: Coolant level sensor is shot
Solution: Replace coolant level sensor. 2001 Impala How To
Prevention: nothing

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Problem: Oil leaking under the engine, dripping off oil pan
Cause: Leaking oil pan gasket.
Solution: Unless the oil pan is leaking profusely, you can get away with not replacing it. It is not a cheap fix to do on its own (500+ dollars) as the engine cradle needs to be removed to replace the gasket. If you are getting your transmission rebuilt, ask the shop to replace this gasket while they are in there.
Prevention: nothing

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Problem: I’m getting some popping noises under braking or acceleration
Cause: If your struts mounts are old, this could be the problem. If not, check for loose cradle bolts as if these aren’t torqued to spec, the cradle moves around and makes a lot of noises that I’d rather not hear.
Solution: Torque the cradle bolts to spec. Tightening cradle bolts - 2000-2005 General Impala Discussion - NAIOA
Prevention: be sure cradle bolts are properly torqued any time the cradle is dropped

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Problem: Exhaust randomly got louder
Cause: Rusted out Resonator
Solution: Replace Resonator
Prevention: Remove heat shield from resonator, they trap and hold water causing a premature rust on the top.[/quote]

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Problem: air conditioning blow cold on one side and hot on the the other (only cars with dual zone climate control)
Cause - blend door actuator motor is burned out
Solution: replace the blend door actuator
Prevention: none

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Problem: windshield wipers not going to park position when turned off
solution: remove cowl and look for a small metal tab on the wiper transmission. This usually gets bent outta place and the wipers don't know where to park. straighten that tab out.

 

Wow Chi lot of work on your part! thanks for posting...

 

Chibi did not compose this (as he stated, it was a copy/paste from IffyG on NAIOA). Regardless, a lot of people I am certain had their hands in sourcing the information over the years (IffyG just added it up). All great stuff!!

Just to add my 2 cents:
Problem: Grinding noises while turning, random activation of traction control, service traction system light on etc
Cause: Bad wheel hub
TIP: To help determine the problem wheel hub, if you turn to the left and the wheel noise starts, it's the right bearing.
Could also be stated, if you turn to the right and the noise goes away, it's the right bearing (but most people think about when the noise starts).
If the noise happens regardless of which way you turn, then it might be both bearings.

My Monte had one bad bearing, but a friend of mine has a '97 Grand Prix that both were bad. I just went through all this.

 

Added, thanks!

 

Regardless if the info was from another website or not, I know its good need to know info and I will soley rely on it because half of the list I either went through or going through...
Thanks Chi!!!!! Good lookin out!!!

 

Does any body has a repair manual for a montecarlo 2000, im in mexico and we get to have those here, i got a propble with the a/c is not working and the temperature gauge is´nt either. Saludos...

 

i have been trying to get on naioa and nothing i havent been able to log on so i think it is usless to get any tips form them oh well i tryed

 

what i mean is i am getting water in my cabin from the rain

 

Turn off the car with the wipers up, pop the hood, take off the cowl and see if there are any water proofing problems there.

 

Thanks for the info Chibi !!!!