have spent the last week working on my sister's 2002 TB with the 4.2...sunday nite- replaced fan clutch. clutch had failed and caused engine to run hot. when putting everything back together, the neck broke off the radiator when i put the hose back on. the plastic was extremely brittle when i checked why it had broke. so monday nite- new radiator. when i finished putting it all back together and cranked it up, there was a loud squeal or screeching noise coming from passenger side engine area. no noise at idle, but as rpms go up, noise starts and gets louder as engine speed goes up. already late, so didn't take time to do in depth investigation, just narrowed sound down to area it seemed to be coming from. most likely culprit seemed to be belt tensioner. next nite, replaced that part. noise still there. so i checked ps pump. had fair amount of wiggle, so i figured maybe bearrings in the pump might be problem. took next nite off. that leads me to thurs. nite. installed new ps pump. grrrrrr!!!! noise still there!! this time did more in depth searching. took serpentine belt back off and started engine again. noise still there. noticed an exhaust leak also. took exhaust shield off and inspected shield and manifold. obvious scorching on inside of exhaust shield in area that corrulates to area where manifold is leaking. my question is, could the exhaust leaking be making the squealing noise? i am inclined to believe at this point that either the exhaust leak is making the noise, or there is an internal problem in the engine itself making it. cant be any of the belt driven parts because noise is still there and loud as ever with the engine running without the belt on...i would really appreciate some help diagnosing this one...it has me stumped. pretty mad at the whole ordeal also...told my sis, between what i have spent on parts and wages lost due to taking off work to attempt to fix her (piece of junk, my opinion), i could have put a nice down payment on a real sweet explorer for her....i will try to get video of the noise tomorrow if it will help with any ideas...
high pitched squeal coming from engine when revved
- Thread starter texreb22271
- Start date
Mooseman
Moderator
Could very well be the exhaust manifold. They have been known to develop cracks. Check with an inspection mirror or camera before taking anything off except the heat shield. Basically, don't replace anything until you CONFIRM a part has failed.
Here's a tip:
Here's a tip:
You don't walk into a biker bar and say "My Harley has a problem but it's a piece of junk so I'll buy a Honda instead" and expect to survive.
Tiggerr
Member
We know, for a fact, there is a major exhaust leak at the manifold. So at very least, gasket has failed, or manifold is cracked.
Wondering if exhaust leak could cause noise described in original post.
(this is the sister posting....my brother is a died in the wool Ford person...I love my Trailblazer....but this mess is driving me nuts...not to mention leaving me stranded. Ideas, inspiration, experience, all welcomed. TIA)
Wondering if exhaust leak could cause noise described in original post.
(this is the sister posting....my brother is a died in the wool Ford person...I love my Trailblazer....but this mess is driving me nuts...not to mention leaving me stranded. Ideas, inspiration, experience, all welcomed. TIA)
Mounce
Member
Start the engine and narrow it down. Not much else it can be since you have eliminated the serpentine system. I doubt its anything internal but if it is, expect catastrophic failure to come soon because I've never heard an engine make a squealing noise internally.
Sounds like you've got it pretty narrowed down to the exhaust manifold, just make sure that's the issue before replacing it.
Sounds like you've got it pretty narrowed down to the exhaust manifold, just make sure that's the issue before replacing it.
Mooseman
Moderator
I have. It was a spun bearing and it also had a knock. It was a horrendous noise, not just a trivial squeal. Heard it also in a 4.3L V6 that spun bearing #1. It would be OK at idle but made the horrendous screeching above idle.
Would it be possible to record a video of the noise and upload it to Youtube?
Would it be possible to record a video of the noise and upload it to Youtube?
Tiggerr
Member
Was thinking that too #1 bearing. I've seen cam bearings do that too. Horrid sound. Can't recall the setup on these I've never had mine apart... Timing chain guide/tensioner maybe?Mooseman said:
Can't see a manifold making that kinda noise tho. Whistle maybe but not a screeching sound
the exhaust leak is VERY obvious to hear... and the horrid noise is too once engine starts gaining rpm. have a sinking feeling that it is coming from first or second bearing on exhaust camshaft... did a little online searching, none of the standard parts houses have cams or bearings for this engine. couldn't even find them on rockauto.com. did find several salvage yards with complete heads listed on ebay and even a couple that already been refurbed...
https://www.youtube.com/watch?v=094YppFlBtI
https://www.youtube.com/watch?v=094YppFlBtI
Mooseman
Moderator
I'm sorry to say mine sounded exactly the same, exhaust leak and all. I've never heard of a camshaft bearing going bad ever on any engine. Not enough speed or stress. They spin at just half the speed of the crank. If you drain the oil, you might find metal shavings. Whatever it is, it's not healthy. Easy enough to take off the valve cover to investigate.
I wonder if it's possibly the timing chain. Knowing this part of the engine intimately, maybe the plastic on one of the shoes fell off and the chain is rubbing on the metal backing. Maybe the oil pump? Haven't heard of one of those failing before and if it did, the engine would be starved for oil. Something is rubbing badly to make this noise.
My bet would be a main bearing.
How many miles on the engine?
I wonder if it's possibly the timing chain. Knowing this part of the engine intimately, maybe the plastic on one of the shoes fell off and the chain is rubbing on the metal backing. Maybe the oil pump? Haven't heard of one of those failing before and if it did, the engine would be starved for oil. Something is rubbing badly to make this noise.
My bet would be a main bearing.
How many miles on the engine?
Tiggerr
Member
+1Mooseman said:
Sounds nasty for sure. Was wondering about timing chain guides, but that sounds like a rod or main bearing. I have seen a balancer squawk like that once too. It had separated and would turn inside itself as rpm went up but fine at idle.
Manifold definitely leaking, but. That's not the source of that particular noise.
first: mooseman
i have seen the results of cam bearings spinning and blocking oil passage on older engines. that was what i was wondering might have happened here...timing chain issue? maybe...have never dealt with a double overhead cam set up before...only timing chains i have ever dealt with were on 1970's and 80's ford and chevy v8s. kinda felt oil pump fine. although i know gauge on dash isnt exactly accurate, it never fluctuates and maintains a reading of right at 40 lbs all the time. the truck has 270,000 miles on it...was wondering if possible to run engine with valve cover removed to be able to visually confirm/ deny cam problem?
tiggerr
it is kinda hard to tell from the video, but the noise is definitely coming from the upper half of the engine...it is the loudest right in the area of the front of the valve cover on passenger side of the engine. i honestly have never heard a car engine make a sound like that before, only industrial electric motors when a flywheel or pulley was rubbing another metal part badly.
triz
i had already replaced water pump and thermostat last fall due to pump leaking around pulley shaft. i am not sure how much it overheated, i wasnt with her when that happened. knowing her, it didnt get that hot. she tends to freak out at the slightest hiccup. she had a towtruck bring it home.the fan clutch had actually been going out for a while. it started throwing codes and lighting the cel month or so ago. just hadnt fixed it yet because money was a bit of an issue. that one has the most expensive clutch i ever seen...
Here's a tip:
Spoiler
mooseman....
not really much of a fan of harleys either....already had that issue more than once...lol
i have seen the results of cam bearings spinning and blocking oil passage on older engines. that was what i was wondering might have happened here...timing chain issue? maybe...have never dealt with a double overhead cam set up before...only timing chains i have ever dealt with were on 1970's and 80's ford and chevy v8s. kinda felt oil pump fine. although i know gauge on dash isnt exactly accurate, it never fluctuates and maintains a reading of right at 40 lbs all the time. the truck has 270,000 miles on it...was wondering if possible to run engine with valve cover removed to be able to visually confirm/ deny cam problem?
tiggerr
it is kinda hard to tell from the video, but the noise is definitely coming from the upper half of the engine...it is the loudest right in the area of the front of the valve cover on passenger side of the engine. i honestly have never heard a car engine make a sound like that before, only industrial electric motors when a flywheel or pulley was rubbing another metal part badly.
triz
i had already replaced water pump and thermostat last fall due to pump leaking around pulley shaft. i am not sure how much it overheated, i wasnt with her when that happened. knowing her, it didnt get that hot. she tends to freak out at the slightest hiccup. she had a towtruck bring it home.the fan clutch had actually been going out for a while. it started throwing codes and lighting the cel month or so ago. just hadnt fixed it yet because money was a bit of an issue. that one has the most expensive clutch i ever seen...
Here's a tip:
Spoiler
mooseman....
not really much of a fan of harleys either....already had that issue more than once...lol
Mooseman
Moderator
Oil pressure gauge on the dash is fake. Readings are fabricated by the PCM to simulate them. It's just a pressure switch, just like good old fashion idiot lights. If there is low/no pressure, gauge drops to 0 and you get a message in the DIC. Since it never dropped, we'll assume you have pressure.
It would be difficult to run it with the cover off as you have to remove the intake manifold but suppose you could reinstall it, the coils are normally held on the cover but bolted into the head. A lot of trouble if you ask me. And you would have a lot of oil slinging from the chain and gears.
Start with just visually checking the valvetrain. In any case, at 270k miles, I think it has had a good run and time to retire it rather than pour money and time into it. If the body is really good, then maybe a good used engine is a possibility.
It would be difficult to run it with the cover off as you have to remove the intake manifold but suppose you could reinstall it, the coils are normally held on the cover but bolted into the head. A lot of trouble if you ask me. And you would have a lot of oil slinging from the chain and gears.
Start with just visually checking the valvetrain. In any case, at 270k miles, I think it has had a good run and time to retire it rather than pour money and time into it. If the body is really good, then maybe a good used engine is a possibility.
mooseman
unfortunately, even with the high miles, retiring it really isnt an option. she just bought it last summer from used dealer, and is still making payments on it. the body is actually pretty cherry. only very slight hail damage on hood that you have to look real hard to see and a couple rock chips on windshield. paint is perfect and interior is way above average for vehicle half its age. we havent talked to the dealer yet, perhaps when we do, we can simply trade it back to him for something else. other than that, i simply have to do whatever i can to get it right. i went ahead and fixed rocker arms on my little buick for her to drive for now because her TB is gonna have to be put aside for now. run out of time and funds for it for now...thank you for your advice and assistance. when i have time to pull valve cover and check things out, i will post what i find and let yall know...
unfortunately, even with the high miles, retiring it really isnt an option. she just bought it last summer from used dealer, and is still making payments on it. the body is actually pretty cherry. only very slight hail damage on hood that you have to look real hard to see and a couple rock chips on windshield. paint is perfect and interior is way above average for vehicle half its age. we havent talked to the dealer yet, perhaps when we do, we can simply trade it back to him for something else. other than that, i simply have to do whatever i can to get it right. i went ahead and fixed rocker arms on my little buick for her to drive for now because her TB is gonna have to be put aside for now. run out of time and funds for it for now...thank you for your advice and assistance. when i have time to pull valve cover and check things out, i will post what i find and let yall know...