wyovino

The car is a 2000 C2 tiptronic Cab.

I had the IMS, RMS, X51 Oil pan, Low temp thermo upgrades done with LNEngineering parts last week as preventative maintenance. There were absolutely no issues with the car before-hand. As soon as I started the car after the upgrade, I noticed a higher pitched sound that wasn't there before the work was done. Not a squeal, but a sound that wasn't present before.

The sound increases with RPMs whether the car is in gear or not. It's not a high-pitch sound per se, but a higher pitch sound than the normal engine rumble. It's a whine which reminds me of when I used to put heavy-duty snow tires on my cars. Before I had the work done you couldn't tell that the engine was in the rear, now it's very obvious. The mechanics don't hear anything unusual, but I just know it sounds different to me.

There is no unusual sound outside of the car or in the engine compartment, only in the interior. We had the car on the lift and revved the engine in gear and in neutral, and checked fluid levels. Everything looks good.

At this point I'm considering modifying the cats just to drown out the sound. Aside from that, any other ideas?

Barn996

Do the FisterD mod on your mufflers(unless you already did).

RF5BPilot

I had no noticeable, audible change after the LN IMS bearing, new RMS & clutch. I can't think of how any of these changes would make a difference if correctly installed.

wyovino

I don't think the mods themselves caused the change in interior noise. I'm at a loss to figure it out.

Eharrison

Honestly? I'm betting you're listening extra hard now since doing the repairs/PMs. I'm like that too.....

Did the shift normally feel like that?
Did the engine normally vibrate like that?
Was that squeak there before?
....

Pac996

Any noise dampening matterial that could of been removed?

onefastviking

Not uncommon if old and weak engine mounts and trans is removed without properly supporting the engine.
What happens is the weight of the engine is all or mostly put on the old weak engine mounts and then they fail right away or very quickly after. Sometimes just one will fail, sometimes both.

So check the mounts, look for sag, height difference, or even and unevenness from where the bolt goes thru. Sometimes you can even just look at the exhaust tips and see that one is lower than the other. Also look for the dreaded leakage. Then replace as needed and I would bet that your interior noise will be resolved.
Easy to check, easy to repair, parts should run around $400.00 +/-

Divot

+1

I am the same way. I listen too hard all the time. If someone else drives my car with me as a passenger (which I love to do with guys that never have driven a p-car), I start feeling and hearing things when I get back behind the wheel. It's all in my head.

Did you have it done at Rudtners? Did Bill listen, or one of his guys? I would trust Bill. He has a good ear, and should be able to tell if something doesn't sound right.

I'll be at Nassau Coliseum this morning in my 996, watching some of the autocross. If you can swing by, I'd like to have a listen.

RF5BPilot

One exercise is to treat the symptom as something new and diagnose it from there.

wyovino

@onefastviking: I just checked the clearance on the exhaust tips. One is about 1 finger and the other is just under two fingers. Does this point to the engine mounts or is that amount of difference typical?

@Divot: Sorry I just saw this now or I would have headed to the Coliseum to take you up on your offer. Yes, Bill did the work and was great about checking out the car when I brought it back. The engine sounds fine except from inside the car.

I agree that I do have the tendency to "listen hard". That comes from many years of boating, where an unusual sound could mean that you might get stranded somewhere you don't want to be. That being said, I noticed the difference as soon as I started the engine, without straining to hear.

Jake Raby

I bet you are using Mobil 1 oil, aren't you?

Is it a type of whirring sound that changes pitch with engine RPM changes?

Eharrison

Don't be so vague! Why those particular questions?

wyovino

The shop used Motul 5w 40 Synthetic.

onefastviking

Adjustment of tips and or rear bumper could take up a little but from what you have complained or explained, I would take a bet that the right side (passenger side) is the 2 finger tip and yes you probably have either a bad motor mount or a sagging one which is transfering some more vibration and noise than you are use to.

You stated it's a 2000 model so it's 10 years old, I'm guessing atleast 60K miles from the repairs you are doing, maybe even more, and it's probably never had mounts replaced so it's not an uncommon failure. Have them check the trans. mount also since it works together with the engine mounts.

It sounds like you have a good tech working on it, have him or someone that knows check the mounts and see if thats causing or contributing to the issue.

Let us know what you find.

wyovino

@onefastviking - Your theory makes the most sense to me. The car has 38k miles and yes, the 2 finger tip is on the right side. How did you know that?

Do motor mounts always leak when they're shot? We had the car on the lift and didn't notice anything leaking, though we didn't specifically look at the motor mounts.