Squealing sound during acceleration [Archive] - GrandAmGT.com Forum


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04-06-2009, 12:35 PM
For about a week now I've noticed that my engine has a loud squealing sound only when I'm accelerating and usually only over 2500 RPMs. Normally I'd suspect the belt but since I just replaced the stock one with a gatorback belt less than 10K miles ago I'm hesitant to say that's the problem. When the car is making this sound, I've noticed my torque seems a bit less than normal and I can't accelerate nearly as fast as before. It's like the engine is bogging down. I tried opening the hood and using my hand to rev the engine but I can't duplicate the sound that way. It only seems to make the sound when the engine is under load.

On top of that, I've noticed a ticking sound when the engine is still cold that seems to go away when it warms up. The ticking frequency increases as I apply gas and decreases when I let off the gas. I'm not sure if this is connected to the squealing though since this normally goes away when the car heats up to normal temps.

I'm almost at 70K miles so I'm considering a transmission fluid change to see if that helps. I know I tend to drive a bit more aggressively so this may be a wise choice anyway. I figure an oil change can't hurt at the same time so that's in the plans for this week or next as well. I did find a small oil leak over the last year or so that causes me to bleed out oil over the course of 4-6 months. Not a fast leak but enough that I need to add more oil before the next oil change light comes on. About 3 weeks ago, I added a little "stop leak" to the oil (I've used synthetic oil since about 50K if that makes a difference) and I'm seriously thinking that stuff may be gumming up my engine. I wish I hadn't added that now but I was too focused on stopping a minor oil leak at the time.

So, I'm not really sure what the problem is although I'm leaning towards the "stop leak" oil additive. Hopefully an oil and transmission fluid change will restore my power but if it doesn't, where should I start looking next? I'm not sure why this would cause the squealing sound either so if someone can enlighten me I'd be much appreciative. Thanks.

04-06-2009, 02:46 PM
something with the transmission? like clutches slipping or something?

the ticking sound sounds just like normal GM piston slap, which goes away when the car warms up. this is nothing to worry about though. my parents had a 2006 3400 powered vehicle that did it from early on and they were gentle with it even. so thats normal.

04-06-2009, 03:25 PM
lifters not piston slap.

The belt can go bad after 10k. How long do you think that gatorback was on the rack before you got it? Put some motor oil or tranny fuild on the belt, to see if the squealing stops. I know our 3100 likes to slip at high RPMs.

04-07-2009, 09:50 AM
Maybe I'm naive but wouldn't putting oil on the belt cause it to slip more? Obviously I wouldn't soak the thing but it seems like oil would be counterproductive to preventing slippage if that's what's causing the squeal. I'm willing to try it but I'd like some 2nd opinions on this one just in case.

Right now I plan on adding an engine degreaser and then changing the oil to hopefully get that sludge out that I was stupid enough to use in the first place. I also bought enough transmission fluid and a filter to change that out too. I know the book recommends this at 100K miles but my car's going to get it at 70K since I bought it in D.C. and I drive it around 110 MPH here. I figure that's enough abuse to warrant an earlier change just to be safe.

Hopefully this will restore my lost torque and if I'm lucky get rid of the squealing too. I'm not holding my breath on the squeal but since it only started up about a week ago at the same time I noticed the torque loss I'm hoping they are directly related.

Any more input or ideas on this will still be welcomed.

04-07-2009, 11:04 AM
Could be the belt tensioner going out.

04-07-2009, 02:16 PM
Maybe I'm naive but wouldn't putting oil on the belt cause it to slip more?

Yes but hear me out. If you put a little oil on the belt and it stops squealing, the problem is somwhere in the belt system. Also look under your hood above the belt, do you see alot rubber caked up on it?

04-07-2009, 09:36 PM
The belt looked fine when I inspected it the other day but I'll take another look. it's not that I don't believe you on the oil thing, I just want to make sure I'm not going to cause more problems if the squealing isn't actually being caused by the belt. If it was the belt, I can't figure out why it never squeals when I'm under the hood and revving the engine. It only squeals when the car is accelerating. Wouldn't a belt squeal whether the car was moving or not?

04-15-2009, 01:24 PM
The mechanic got a good look at it today and I'm pretty sure he found the problem. Looks like my catalytic converter is clogged up which is stealing all my power. The ticking and squealing noises were then located when he found that one of my bolts on the front exhaust manifold (right above the AC compressor) broke and the back pressure was causing the metal there to vibrate. Higher backpressure changed the ticking into a whistle sound that was very similar to a belt squeal. He even showed me all of this to prove that's what caused the noises and he also showed me the outside of the EGR valve that was starting to change color due to all the extra exhaust heat flowing through it. He said that if that bolt head hadn't blown off, I would likely be looking at a melted EGR and the car wouldn't run at all.

So, now I need a new cat, downstream O2 sensor and exhaust manifold gasket since they will have to drill the old bolt out to replace it. I'm seriously considering getting headers and a high flow cat since this is probably the only time I might get the chance but the prices are nearly triple what the repair parts will be.

04-16-2009, 06:14 PM
Go for headers, you won't be dissapointed. High flow cat is good but don't expect too much if anything.

04-16-2009, 10:23 PM
The headers are going to cost me too much so I'm stuck with just the OEM cat. I ordered it all last night except for the exhaust manifold bolts. Does anyone know of a website where I can find those? I've looked at every auto parts store online that I can think of with no luck. I need those bolts to replace the broken one and any others that may break during the manifold gasket swap.