94eg!

Hello all,

My sister has a 2008 RDX with 119k miles on it. Today she brought it over and we did some maintenace on it.

- New OEM Coolant
- New NGK SILKR8A-S plugs (Same as OEM)
- New ATF (went with Honda DW-1)
- New Rear-Diff fluid (Honda AWD fluid)

During the process, all removed o-rings or crush-washers were replaced.

Problem: After finishing we started it up and it sounded funny. There is an odd rattle noise when off throttle. It sounds like a loose heat shield. It happens when I rev the engine, it happens when I let off throttle while driving. We took it all apart again and checked for loose stuff. Everything looked perfect. All bits accounted for.

Has anyone had this problem before? Could it be the plugs?.....DW1 instead of now-obsolete Z1 fluid?

I've been all over this motor with a screwdriver stethascope and can't find the source. Any insight would be greatly appreciated.

Tomtwtwtw

This may or may not help...someone else had a weird rattle recently and it was a fairly obscure bolt that was the culprit.

https://acurazine.com/forums/problem...-noise-924086/

94eg!

Thanks for the link.

The intercooler mounting bolts (in that thread) are definitely secure. I even removed & reinstalled the whole intercooler completely to verify. We can easily replicate the sound by revving the engine in neutral. Whenever the throttle is closed the noise appears as revs fall, till it finally hits idle again. She revved the engine over & over while I searched for the sound. I tired pushing on the intercool at every angle and the sound never changed.

It's loudest from the passengers side when above, and it's loud all over when I'm underneath. I checked all the exhaust pipes and heat shields. Not knowing is gonna drive me crazy.

The only thing I didn't double check was the spark plug gap (NGK's come pre-gapped).

bluecarbonfiber

check the level of oil you have in the vehicle if its right at the second hole or above it will cause a rattleing sound i had to change the oil a second time to make it go away

justnspace

iTrader: (1)

94eg! when the heck did you get an RDX?

ohh, wait...just read the OP.
never mind me

Tomtwtwtw

Is it definitely not coming from the valve train?

Did you drop a wrench or a bolt down into the engine bay abyss?

94eg!

One part fell into the engine bay when removing the intercooler. It was a sleeve for one of the rubber mount bushings where the intercooler connects to the intake tube. It fell all the way thru and was easily recovered. Everything was completely accounted for.

As for the oil, I checked it. It was right at the top dot. Though we did nothing to the oil, so it's kinda weird that after were done it was suddenly making noise. I can always try draining a little next time she comes over, though this sounds rather odd to me. Any info on what type of noise you had?

Tomtwtwtw

Any possibility of capturing the sound in a video and uploading? That could definitely help with the diagnosis.

bluecarbonfiber

it was a ticking rattle sound on the passanger side and it came from basically right where the oil filter area was at the time i had just changed my oil too and nothing else was done

94eg!

If I can get her to come back, I'll capture a sound. She doesn't seem hardly phased it started making the noise, so I doubt she will come back soon (busy busy). I will also try draining some oil and see if that helps. Problem is we didn't touch the oil. We only changed the ATF and Coolant. Still worth a shot.

Richard Sun

Hey did this ever get revisited/resolved? I had this IDENTICAL thing happen, except all I did was replace the sparks. I did the same thing and took it all apart again down to taking the sparks out and back in again but it had no change in the off-throttle rattle. Will check oil level but was curious if you actually identified the problem for sure.

94eg!

It ended up being the waste gate on her Turbo. Turbo was replaced with a used one and it was fine after that. She promptly sold the car. Sorry. :\

Richard Sun

whoa, the email notification I got that you replied had completely different text, describing a heat shield rattle. Did you edit your response completely? sorry just completely confused me. =)

94eg!

lol yup. Sorry I wrote that entire speech and didn't realize what thread this was you posted in. I thought it was a different thread in the 3G TL forum. Glad I re-checked the 1st post.

Sorry to mess with your head!

Richard Sun

ha! ok, well thanks. That sucks if it's really the waste gate. i don't want to replace the turbo. There seems to be some aftermarket wastegates around but i'm not sure how to replace it separately.
The car is driving just fine (mine only does the chatter on throttle off, during idle)... so maybe it's ok. i'll have to confirm if it's coming from there still.

94eg!

There were a bunch of check engine lights when hers failed. Hopefully it's unrelated.