First off, i posted on another a few months back asking about this loud chattering noise coming from the underside of my MCS. I figured I'll just start another thread to consolidate my findings. After some further investigation, I strongly believe that the sound is caused by a leaking exhaust manifold/header. It is not the clutch bearing as suggested by a few fellow NAM members. I tried depressing the clutch while the car is in idle and the sound did not go away with the clutch engaged. Here are 2 other videos I shot while the car is in idle (sorry about the bad quality lighting. it was hard to get some decent light from underneath) What do you guys think? Is my suspicion correct about a leak in the exhaust manifold?

chattering

hissing sound

 

You can go to a Home Depot type store and buy some plumbers "gas leak" liquid. Its a blue colored material. With the engine cold, take out the foam applicator and apply a liberal amount of the liquid around the portion where the one pipe/flange, slips into the other on your first video. The material is glycol based so be sure to wipe up anything that spills so any animals do not lick up. Have somebody else start the car, if the connection is leaking you will see soap bubbles forming.

It does sound like you have a leak down there. You can repeat the process on other fittings once the exhaust cools.

 

Have you checked to be sure it's not the chain tensioner?

 

Sounds like an exhaust leak to my ears. The connection between manifold to cat seems to be quite a common place for leaks to be found.

Check your lower engine mount too. Excessive fore aft movement adds stress to your exhaust system.

 

Smoke test.

Any shop worth their salt should have a smoke tests machine, that is going to be the quickest diagnostic you can do short of visually seeing the problem.

I've seen leaks on the headers at three places, top two are the most common:
1. Bottom of the precat
2. Center of the collector between all 4 cylinders (not easily fixed)
3. At the second cat

Problem with the videos is; the first video sounds like either an exhaust leak or rod knock, yay Youtube quality!! And the second video sounds like a large vacuum leak, again yay Youtube quality!!

Does the car have a SES light on? Stored codes?

 

So far, i don't have SES light on in the car. It seems like the general consensus so far is that the problem stems from a leak somewhere on the exhaust manifold. I was planning on just removing the manifold and taking it to a welder and have him weld up the leak/crack.

Would a welder be able to fix any of the above issues?

thanks

 

Spray it with soapy water in a spray bottle when starting the car cold. The exhaust leaks will cause bubbles.

 

I was about to pull the exhaust manifold out this morning. After removing heat shield and looking around the area where the manifold bolts onto the engine and not seeing any noticeable cracks, I thought I start up the car again one more time. It's kind of hard to pin point the source of the vacuum leak. It does sound like it's coming from somewhere near the intake area, instead of from the manifold. I guess I have some more detective work ahead to try to find the source of the leak before removing the exhaust manifold.

 

Did some digging around today to check for the source of the leak. I can't seem to find anything that might be the cause. I also did a visual inspection on the vacuum supply line to make sure it was not broken or disconnected. I'm now stumped. Are there any other lines or area that would cause a vacuum leak in the R53?

 

Check this video out, it may help you find the leak.