PaulFM

Hey everyone...

So I consider myself as a sort of amateur DIY kind of guy, but I ran into something which I thought many of you may be able to chime in to steer me in the right direction.

I bought a 2010 E350 with approx 68k miles on it a few months back. Currently it has about 74k miles on it, and not knowing if the spark plugs were previously changed or not, I decided to go ahead and change them out anyway.

I replaced the plugs with the ones listed in the owner's manual (Bosch Y7MPP33). Even though they came pre-gapped, I checked the gap on them and they were all to spec (0.031). I also torqued them to the specified torque (17 ft lb). I kept the same coils and did not change them.

The job seemed to be straight forward. Then when I turned the car on, I heard an odd noise at idle. Seems to be a tapping noise? (My friend said the car now sounds like the older MB diesels.) The car didn't have this noise before.

I tried to capture it in the video which I have posted here:


The noise is a steady noise. It's not really loud, but clearly audible. There are no check engine lights. Car runs fine with no loss of power. The noise doesn't increase with increases in RPM either. It's only audible when the car is in idle (even when in Park, Drive, Reverse, and Neutral).

I thought maybe the new plugs were bad and swapped the new ones out for the old ones and I am still having the same problem.

Wondering if anyone may have some idea what I should look into? Should I have also swapped out the coils when I changed the plugs?

Thanks in advance!

Arrie

well, obviously it is not the plugs.

In my car the engine cover/air box is held in place with four big clamps that go over "*****" mounted on the engine. It is easy to install the cover not getting one of the clamps on fire wall side in place correctly. This could cause the box to vibrate and make noise at clamp when the engine is on idle and engine shake normally is the worst. Should be easy just to put weight on the box at each corner while on idle to see if it helps. Also make sure the metal wire holder is in place correctly behind the box by the fire wall.

PaulFM

Thanks for your reply!

I checked it out and everything was in secure and tight. Put weight in it too and no luck either. This issue is really busting my head...hahaha

KEY08

Sounds like a top fuel dragster. LOL I have no clue what that may be if it isn't running up or down with RPM. I hope you figure it out without a lot of extra effort.

JoeTX

If the noise doesn’t increase/decrease with RPM’s I’d look into whatever under the hood has a constant speed. Radiator cooling fan? You may have bumped it just enough while changing the plugs so it’s hitting the shroud or something’s hitting it. You only hear it at idle because any higher RPM drowns out the sound. Total WAG though. Good luck.

PaulFM

So the sound magically disappeared the other day...I'm guessing the car just wanted some attention? Haha....anyway, been driving around for a while and haven't heard it again. Still no clue where it came from, but I'm not complaining since it's gone (for now....).

Thanks for chiming in folks!

Mistah Hassan

Hi mate, I recently changed my spark plugs and I also ran into the same problem! But few miles of driving later, the engine must’ve just wanted to wear into the new part lol