My car started making some weird rattling type noise last week near the front of the car. When I start the car in the morning with the car cold, the sound happens after about 10 seconds of the car idling, and will keep doing it very loud until the car been running for about 10 minutes and has warmed up, then the sound goes away.

Once you start driving though, the sound is back, even if the cars been running for awhile and is completely warm. It doesn't matter if it's warm outside as well, or cold outside, it still does it. If you have the car at a constant 2000RPM just about cruising along, the sound will happen, no matter what gear you're in.

I've had my car at my mechanics all day, and they weren't able to find the cause of the problem. They can hear it making the sound clear as day, but can't pin point it. They took my heat shield off, checked the entire exhaust to make sure nothing is loose, about to be loose, or broken. They checked the entire underbody of the car as well and looked for the same things but everything is solid.

Since the car makes the sound louder when the car is cold in the morning, it's staying overnight and they are going to try and pin point it in the morning. The car makes the sound regardless if it's been running for an hour straight or completely cold, it's just the loudest when it's cold, which is why they are trying again tomorrow.

Any ideas as to what the cause may be would be appreciated.

VIDEO OF THE SOUND

 

Holy moly that is loud. No idea!

 

Your sound and simptoms sound familiar. Last month I had a new alternator installed on my '97 Max. After a few weeks I got that rattling sound on start up that went away after warm up. Then it didn't go away after warm up. Last Friday my serpentine belt fell of on th hiway. One of the aternator mounting bolts was loose, fell out, belt off. Check the mounting bolts on everything driven by your belts.

 

I see in your sig. you have a 6mt. Could that be a tranney/flywheel issue? When my bros Z clutch was going out he had a similar noise in addition to extremely hard shifting. Are you experiencing any of that as well?

 

I'll get them to check this as well, good call. They actually tightened the belts about 3 weeks ago so maybe they messed something up and put too much tension on it, and made something fail.

 

I haven't noticed any big difference in the shifting really, but it's possible that i've just been getting used to it as it's been getting worse. It's something else to try and check for sure. Thanks.

 

sounds like an exhaust leak maybe

 

Or possibly an issue with one of your fans or fan shrouds? Never heard a G do that before.

 

So we're 98% sure we've found the problem, but were going to listen to it again in the morning when it's cold (since it does it super loud when it's cold) to triple check it. We used a stethoscope to pin point the sound super clear.

It seems to be the timing chain tensioner. If you try anywhere around the tensioner cover, you can't hear the sound, but as soon as you put this stethoscope on the cover, boom, super clear and loud, no doubt.

This means 12 hours labour plus parts, frig! We will end up replacing some other parts as well since a lot of stuff will be open anyway. This will be triple checked tomorrow morning though, then priced out, and eventually started. Sucks but it's gotta be done.

 

I'd be 120% sure it's the tensioner before replacing it. I thought my alternator was being loud, so I replaced it...ended up being a loose belt.

 

Yeah there's no doubt about it. I don't know if you've used an automotive stethoscope before (I haven't, this was my first time when my mechanic let me listen), but it's super accurate.

I touched the probe to different parts of the engine, and some spots you can't hear the sound at all. Closer to the area, even right next to it you car hear it a little. As soon as you touch the probe to the timing chain tensioner cover though, BOOM, super loud and clear as day, it's crazy. We tried this all over the engine and only on this spot is it super loud and clear. Keep in mind this was after we checked over the entire car yesterday, which lead them to this spot, then they used the probe to pin point it exactly.

My mechanic is also a member of an auto mechanic network online where theres thousands of posts on different makes and models of cars with problems and what fixed the problem (it's all over north america). It's similar to what car dealerships have for their cars. Everything we read up on for this engine related to this sound and the area in these posts points to the timing chain also, so it was just another thing to help confirm what we've found.

Good call on that though. It's for sure not something we want to take a part and replace if we don't have to. It's 12 hours labour at least, which I would much rather NOT have to pay haha.

Automotive Stethoscope

 

That sucks it turned out to be the timing chain but good that you have potentially found the issue. Keep us posted after the swap is done

 

OK, that's good!

 

So I finally got my car back and the problem is completely gone.

The problem was the timing chain tensioner.

After they removed everything, they could see that it wasn't providing any tension on the chain anymore, and the chain was starting to eat away at it. They also replaced all the chains, tensioners, and guides. All of the chains were very stretched they said, because they could easily get the two top ones off without having to remove the sprockets. When they put the new chains on they had to remove the sprockets. Anyway, the problem is solved and I'm glad to have my car back.

 

Glad you got it fixed. Does the engine feel any different now?