loose plastic or bigger problem?

[huangxin]

ok here's the tricky problem

my car now has a chatter noise after it's been sitting out in the sun. the noise comes out at around 2,000 rpm (yes i know the exact number! just swapped in a cluster lol) only when i'm driving. if i rev the engine in park it just purrs. the noise seems to be coming from the center console or front center area of the car. it sounds like some plastic is loose. the noise becomes easier to hear when i push the engine harder (ie. gets a lil louder), but it maintains at a low volume level. if i have the radio on, or even the windows down i can't hear it.

the noise seems to be related to the outside weather. when it's around 70 degrees, i have no problem at all, even when the engine is fully warmed up after a long drive from work, but when it's parked outside in the sun for a while, the noise comes out.

i'm thinking it might be a pastic part that is loose, but i took apart my center console today and couldn't find anything. i checked under the hood too, nothing really obvious. the only explaination i can think of for the noise occurs at 2k is maybe there's more vibration when rotating faster? or under load? even though i can't really feel anything.

the sound is not detonation, or bearing. it somewhat sounds like valve chatter (not tick), but it really sounds like plastic part or small metal part is loose.

so does this sound like just a small annoyance problem? or am i looking at something mechanical that possibly can do damage if i don't find the cause?

thanks in advance

[huangxin]

just to add a note

the noise only comes out when it's been sitting under the sun when the temperature is VERY hot. kinda like to the point where you can barely stand being inside the car and after you get in the car, everything you touches burns.

the weird thing is that it doesn't go away till after i let the car sit for a while in the shade to cool off. the A/C inside the car does not really get rid of the noise even after it cools off the interior of the car.

[fishexpo101]

Hmm. If it starts at that RPM, that would indicate a possible resonance issue (engine/transaxle/chassis). But should be present when you rev the engine in park. Have you tried revving it in gear to see if make the noise? How quickly does it chatter and does it change frequency with engine speed/road speed? Just an occasional ticking noise or is it constant?

Knowns:
- noise starts at 2000 RPM
- only apparent at speed
- location is central
- car must be sitting in direct sun (warm up the entire car, not just the engine)
- A/C doesn't seem to affect the noise inside the car

That is a toughie. Could be the exhaust shield coming loose or coming in contact with the chassis or the hoses running through the firewall at touching something. Could be a loose bracket in the engine bay, could even be a loose hood (assuming that you removed the hood when you did your engine swap - to get more clearance?) Could be the cowl or windshield (expands with heat, touching something). Could be the dash itself is loose or one of the wire bundles behind it fell or is touching the interior of the dash. Could be something that starts from the inside and runs out - like the condensation drip tubing - might be touching something inside/outside.

To cut down your diagnostic work, have to verify if the problem is inside or outside of the car. Might try one of those windshield masks, the ones that suppose to help block or reflect sunlight away from the interior. Basically trying to keep as much heat away from the dash and center console area and see if the noise is still present or not. If the noise goes away - then the problem is likely to be inside the cabin, and you can explore that. If the noise stays the same, you can concentrate your efforts outside the cabin.

[01loadedLE]

Originally Posted by fishexpo101

....or one of the wire bundles behind it fell or is touching the interior of the dash....

I would suspect that primarily as well. The heat could be swelling the bundles just enough to cause one to touch something and vibrate against it, to where when cold it would shrink and move away from the item it was vibrating against.

I also had heat shield vibrations at that rpm that went away when cleaned of debris and tightened, as well as the engine cover vibrating at that rpm until it was replaced too, but those symptoms didn't go away when cold so I'd look at that wiring first.

[huangxin]

thanks for the suggestions guys

i'm just glad that it's not a bit problem. school is starting next week, so right now i'm trying to rush all my summer work done lol.

i'll get to it as soon as i get everything settled down and give you guys an update.

the 4 bolts are tight on the hood, i raised the 2 bumps supporting the hood up front a little bit too. i've had night or late afternoon shifts all week, so don't know if that solved anything

next time i get a day shift i'll be sure to bring my dad's windshield mask (i don't have one lol). i already checked the heat shield i removed during the engine swap, everything seem to be right on there, i'll get the ones under the body either this weekend or next if i can't squeeze out some time.

i know for sure it's not the engine cover. why? cause i just put the cover back on yesterday haha

anyways, thanks again, i really appreciate the efforts

[huangxin]

ok some update

i went to work today at 4 in the afternoon, and on my way there i kept the engine rpm at around 2200 rpm, the i can't really hear the clicking, but when i push the rpm to 2500 during the acceleration i can hear it again. it's not terribly loud, but loud enough for me to hear each click.

then i parked my car under the sun. when i got off at 6:30 the sun is down, but it was still hot. i just opened my windows and drove the car home without using the A/C. on my way home, i can't hear the click at all. at one point i even rolled up my windows to see if it's still there, all i could hear was the engine.

can this be A/C related? seems like every time i push the car a little harder the clicking noise comes out, but if i accelerate slowly, there was no noise even when the engine is cruising at 2500 rpm, and without turning on the A/C, there is nothing wrong with the car...

now i'm completely out of ideas...

[huangxin]

ok i think i got the problem narrowed down to behind the A/C control assembly

i just drove to the gas station to fill up, while i was driving, i turned on the A/C, and i was able to get the clicking sound when the engine speed is over 2k during acceleration even though it's cooled down outside and the car's been sitting in the garage since i got home from work.

then after i got the clicking sound out, i turned off the A/C, the clicking became quieter and last for a minute or two and it went away.

so, i'm thinking that something either inside or around the A/C button in the control assembly is loose. i'll probably take it out and have a look this weekend and let you guys know what i find.

[huangxin]

i think i got my theory proved.

today after school the car has been soaked under the sun all day, i drove it home without turning on the AC, no noise (yes it was very hot). then i drove to the bank from my house with the AC on, the clicking came back. so i'm thinking it's something around or close to the air duct, the cold air from the AC somehow cause it to be able to rattle.

i don't think it's my AC problem, there was no noise at idle, and the air is still cold.

[gaj1967]

Pull the radio out and move wires and things around. Put the radio back in and see what happens.

Gil

[huangxin]

update

i was driving with a friend in the car. long story short, the sound is not coming from the center console area, it sounds like it's coming from behind or close to the passenger air vent area. she confirmed that the sound is coming from the inside of the car too, so at least it won't damage the car if i keep on driving.

when i looked inside the air vent... there's a lollipop stick inside... who knows how long that's been in there (i'm not the first owner). took it out, but the sound is still there...

i opened the glove box and looked up, nothing seem to be loose. it's getting hot out there, so i didn't take anything apart. any ideas on what i should do next?

the sound comes out only when the AC is blowing cold air, so i assume it's something along the passenger air duct?