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Old 04-18-2006, 01:43 PM
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Make: 2000 Pontiac
Model: Sunfire GT
Engine: 2.4L Twin Cam
Question Knocking / Rapping noise 2.4L Twin Cam

Hey guys, New to this site. Found it while doing a search on my sons 2.4 Twin Cam.
Here's the scoop.
My sons car, a 2000 Pontiac Sunfire GT, 2.4L Twin Cam (LD9) developed what sounded like a rod bearing knock about a month ago. We couldn't pinpoint the exact location of the noise, but, it sounded like a typical? rod nock.
After going nuts just figuring to getting the pan off, the rod bearings looked fine, no visible signs of wear. So, we replaced them and the rod bolts anyway seeing as we had them out. We still had the noise, car ran fine for awhile, just knocking. It didn't get really much louder, but now the engine was starting to idle rough, and would only clean up at about 3000 rpms, idle down and run like crap again...noise and all. Now we thought....lifter?, valve?, possibly, what else would make a knocking / rapping kinda noise?. So, after spending half a day trying to figure out how to get the cam covers off, (yes, we had a Chilton, but it didn't tell about the 2 bolts behind the timing gears), everything looked OK. lifters appeared to be good,(how would they look if bad?) valves springs looked OK.
So we figured at this point, pull the head. WTF......cant get the timing housing off. All the bolts that are visible are out, but it wont move????
I don't want to try to pry it like I read in another post by Lowrider. The Chilton doesn't address this, it just says remove timing housing.
My question is, could it be a bad piston?, wrist pin, valve or something we're overlooking. This friggin car is driving me nuts. It would have been easier to pull the engine.
Someone mentioned timing chain slap. Wouldn't that sound more like "scrapeing" than a knocking?
At this point I thinking about just getting a junkyard engine or I'm thinking of just putting it all back together and selling....knocking noise and all.....as is.
All we want to do is get it running so he can sell it. Car is in good shape, but he's at school in Boston and wants to buy a new car when he graduates in June. He has my car while his is apart in my garage...................and I want my car and garage back.
Any help would be appreciated.
  #2  
Old 04-18-2006, 08:28 PM
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Location: Warren Mi
Posts: 119
Make: Chevrolet
Model: Cavalier
Engine: 2.4L LD9
The origional engine in my 02 cav. developed a knock noise that was the result of very loose piston to wrist pin fitment. Once the head was off the piston could be rocked back and forth while it was in the block still. It would knock untill about 2500 RPM or whenever i put a higher load on the engine.
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Old 04-19-2006, 05:51 AM
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Quote:
Originally Posted by gverb1219
.cant get the timing housing off. All the bolts that are visible are out, but it wont move???? I don't want to try to pry it like I read in another post by Lowrider. The Chilton doesn't address this, it just says remove timing housing.
If you have the "front" engine mount off (passenger side) and the harmonic balancer off and you are sure you've got all the 10mm bolts out then the steel cover should fall off of the 2 or 3 studs it hangs on... no prying necessary...
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Old 04-22-2006, 02:26 PM
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Make: 2000 Pontiac
Model: Sunfire GT
Engine: 2.4L Twin Cam
Question

OK, got the timing housing off. I wasn't talking about the cover itself, but the entire housing bolted to the block. I found that the 2 8mm bolts that hold the tensioner to the housing, also held it to the block. Once I took that off and the 3 water pump bolts off it came right out.
Now, with the head off, I was kinda hoping to see a bad valve or something, but nothing looks bad. In fact, everything looks pretty good.

So, back to my original post.
What was causing the knock. Someone told me it could be timing Chain / gears?? I dont know, I never heard a timing chain / gear sound like a knock.
I think the only thing it could be now is a wrist pin. But no real way of checking that without pulling all the pistons, something I really dont want to do. Engine is still in the car.

I found a junk yard 2.4L TwinCam out of a 2001 Sunfire with 42,000 miles, for $900. Maybe I should go that route.
What would you guys think? Fix what I have or pop in the junk yard engine?
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Old 04-22-2006, 05:53 PM
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Make: Holdiac
Model: GTO
Engine: LS2
every possible thing that can cause a knock/rattle/tick (that i can think of):

loose timing chain, bad timing chain tensioner
bad lifter
bent valve
improper timing (pistion striking valve but this doesn't sound liek a knock on a quad 4... YOU DON'T WANT TO HEAR WHAT THIS SOUNDS LIKE...)
bad wrist pin
spinning or corroded rod bearing
spinning or corroded main bearing
excessive piston to bore clearance
excessive bearing to journal clearance, main or rod
failing oil pump

ALSO it could be a loose flywheel/flexplate bolt. those sound just like a knock.
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Old 01-02-2007, 11:26 AM
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Make: Pontiac
Model: Grand Am
Engine: Quad 4
Have you mike'd the crank? May be out of round, but would think that would show up in your bearings too. If you have the head off you should pull the pistons and check the wrist pins as someone else mentioned. I just went completely through mine, and still have some timing gear noise that kinda sounds like a knock. Rod bearing went out of mine and had to replace the crank and bearings. I have a GM manual, and they mentioned that if the lifters were not put back into the exact same holes, they may get noisy.
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