View Full Version : Need some help, I've got a knocking noise coming from the engine
02-19-2011, 10:41 AM
This is my 2003 grand am gt, yesterday I was driving it and while I was accelerating the engine sounded like it revved very high very quickly, then a loud knocking started.
If any of you guys could identify the noise it would be a great help.
02-19-2011, 11:12 AM
Sounds like one of your rocker arms pulled the threads out of the head. The pushrod is banging around in there and likely causing that noise. I had the same sound when I left one of my rocker's loose on the first 3100 intake I did.
Pop both of the valve covers off and see if any of the rockers are loose.
02-19-2011, 11:28 AM
Thank you for your quick reply. I listened to the knocking and it sounds like it is coming from under the front valve covers. Looking at the engine, there is a water hose in the way of the valve cover that is non-flexible metal, will that have to be moved or can you slide the cover off under the hose?
Also, is this knocking damaging the engine or is it just a noise, meaning should i avoid running it as much as possible? Not talking about driving it, just turning the engine on to hear the noise.
02-19-2011, 12:54 PM
You know where the noise is coming from so there's no real reason to keep running it. Its definitely not doing it any good.
That metal pipe you're talking about does have to come off. Its no big deal, though. Remove the 8mm holding it in to the timing cover, unhook the lines from the throttle body and pipe above the valve cover, unbolt it from the stud below the throttle body and it will pop up and out of the way.
02-20-2011, 09:49 AM
Ok I'm giving this thing a shot today. Also if it helps at all, every time it knocks the engine shakes. And when it first happened the service engine soon light started flashing.
Thanks for all the help
02-20-2011, 10:29 AM
Rather worrying update:
Had my uncle come by who knows engines inside and out, he's saying its not in the valve train, but instead deep in the engine. More than likely a connecting rod let go and the piston is just useless in there, which also probably ruined the cylinder.
He's saying the most cost-effective way to do this fix would to be just trying to replace the engine with a lower mileage one, or to just trade it in for a running car and bite the bullet.
02-20-2011, 12:31 PM
That noise is too light to be bottom end.
Pull the valve covers off and see what's going on. That's cheaper than going straight for a replacement motor.
02-20-2011, 04:50 PM
I agree, that does NOT sound like rod knock to me. That sounds like a busted rocker. Take the valve covers off first and check them. It's a lot easier than fixing broken connecting rods.
The engine probably shakes and the SES light is on because if a rocker is broken that means one of your valves isn't opening... so you probably have a cylinder that isn't firing and/or is misfiring. I definitely wouldn't drive it until you get it fixed.
02-21-2011, 01:16 AM
It's off in Storrs getting looked at by a family friend who, thankfully, agrees with you guys that it is not deep in the engine and instead something easily repairable. Hopefully I'll have it back in a few days working again.
Thanks for the replies I'll let you know how it turns out.
02-22-2011, 07:33 PM
So I got word from the mechanic today, Scott it's exactly what you said, good call sir. Hopefully running it those few times didn't do any additional damage but that is to be determined tomorrow or the next day. Thankfully this sounds like a non-catastrophic injury which means I won't have to abandon the grand am for a legacy gt after all :heh:
02-22-2011, 08:49 PM
Your car will be fine. A heli-coil and maybe a new rocker/pushrod and you'll be good to go.
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