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crouse
03-28-2008, 07:41 AM
Under light throttle either while I'm driving or with the hood open, maybe 1500-2000 rpm, I hear what I think is a knock. Higher than 2000 rpm I don't hear it. It's been doing this for quite sometime. I think I first noticed it after I had new exhaust installed. I thought it was quite strange because the exhaust is now much louder but I can hear this knock.

I think since it's winter and I have the windows up I notice it more than during the summer when the windows are down.

I'm thinking it's not the engine but something else like the belt tensioner or something vibrating against the frame etc? Or could the larger exhaust pipe cause this?

I ordered a new belt and tensioner a few months ago. I replaced the belt but have not installed the tensioner yet.

Also, under WOT throttle I hear a little rattle around 4000 rpm that only lasts a few hundred rpm. Again, this seems like it's a vibration not an engine knock from detonation.

I removed the belt and started my car just to see if it might be one of the accessories causing the knock, but that didn't change anything.

Here is a link to a video file.

http://www.mercurymarauder.net/showcase/misc.php?do=downloadfile&i=11612

Anyone else have something like this? Any help would be appreciated.

Thanks, Curt.
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magindat
03-28-2008, 07:47 AM
Could be the back side of the upside down U that goes over the axle tapping the bolts on the gas tank.

I had that issue and it was, as described, only at certain RPM ranges. It was due to exhaust being pushed backwards slightly. I remedied by cutting 1/2 inch from an accessible pipe joint and re-joining. I am using wrap clamps, so it was easy.

Dennis Reinhart
03-28-2008, 08:15 AM
Is your car a 03A

crouse
03-28-2008, 08:43 AM
Hi Dennis,

Yes, 2003A. Build date: 7/16/2002

Zack
03-28-2008, 09:02 AM
I listened to the video clip.
Definitely sounds like a rod or main bearing.

Disconnect the coils one by one and see when the noise goes away/quiets down.

Dont be alarmed by this, it is really difficult to diagnose a noise from an audio clip.

crouse
03-28-2008, 03:11 PM
I pulled each spark plug boot one at a time and no change.

It seems like it's coming from the drivers side front of the engine like maybe a cam chain or chaine tensioner.

Could the JLT CAI cause a resonance like this?

Or maybe the exhaust? I've two 2.5" Magnaflow cats and 2.5" pipe all the way back to the mufflers?

TooManyFords
03-29-2008, 06:10 AM
Have you had anyone else listen to it?

Mike Poore
03-29-2008, 06:20 AM
You can use an automotive stethascope to isolate where it's coming from, sometimes, or use the poor man's way, with a long screwdriver, and touch various spots of the engine, while leaning down and putting your ear up against the screwdriver handle. If it's internal, believe me, most times, you can tell.

gmtech
03-29-2008, 06:25 AM
hard to tell from that clip, as my car almost sounds the same...can you hear it inside while driving? do you have a oil pressure gauge? whats the readings?

burt ragio
03-29-2008, 07:02 AM
The noise sounds internal to me. Then again it's a five sec. audio clip. You mentoined the noise started after the exhaust mod. Have you done a complete exhaust check for leaks and rubs ?

crouse
03-30-2008, 09:09 AM
Have you had anyone else listen to it?

John, I've had a few guys a work listen to it. They acknowledge that they can hear it but we can't seem to determine where it's coming from.

crouse
03-30-2008, 09:10 AM
You can use an automotive stethascope to isolate where it's coming from, sometimes, or use the poor man's way, with a long screwdriver, and touch various spots of the engine, while leaning down and putting your ear up against the screwdriver handle. If it's internal, believe me, most times, you can tell.

We have one of these at work. I think I'll borrow it for a day to see if I can isolate the knock.

crouse
03-30-2008, 09:13 AM
hard to tell from that clip, as my car almost sounds the same...can you hear it inside while driving? do you have a oil pressure gauge? whats the readings?

Yes, I can hear it when I drive. Mostly at slow speeds. At higher speeds and harder acceleration, the exhaust noice cancels out the knock.

I have the factory dummy oil pressure gauge. I think I'll but a real working one just to make sure I've got good oil pressure.

crouse
03-30-2008, 09:14 AM
The noise sounds internal to me. Then again it's a five sec. audio clip. You mentoined the noise started after the exhaust mod. Have you done a complete exhaust check for leaks and rubs ?

I'm going to spend some time today looking for leaks & rubs.

Any possibility the EGR valve could cause a knocking sound?

MercOut
03-30-2008, 09:32 AM
You spun a bearing, thats what mine sounded like

crouse
03-30-2008, 03:08 PM
You spun a bearing, thats what mine sounded like

I pulled each spark plug boot one by one and no change in sound. Wouldn't a spun bearing stop knocking when the spark plug boot is pulled?

superford3
04-02-2008, 02:03 PM
I would say a bearing problem also but then again they have chain problems also that cause that noise

crouse
04-03-2008, 06:52 PM
I'm bringing it to Apple Valley Ford on Tuesday to have their SVT technician try and diagnose the problem. I'll let your guys know what he find.

Hacklemerc
04-03-2008, 07:50 PM
THats how my car ended up getting a new engine. I heard a slight knock at idle and then it just kept getting worse. Get it checked now. I waited and then had to replace the motor. No fun at all.

max454
04-05-2008, 08:27 AM
I pulled each spark plug boot one by one and no change in sound. Wouldn't a spun bearing stop knocking when the spark plug boot is pulled?

Anyone on this ?

sailsmen
04-05-2008, 08:51 AM
Pulling a spark plug boot eliminates spark.

The parts still rotate and the cylinder still experiences compression

crouse
04-08-2008, 07:43 PM
Just an update. Picked up my Marauder this evening from Apple Valley Ford and their SVT mechanic listened to it and drove it and said it's definitely not anything major like a rod bearing or main bearing. He does acknowledge that there is some kind of noise. Maybe something in the valve train but nothing to worry about. I'm going to keep an eye on it and see if it get any worse.

Didn't charge me anything either.

The sound seems to come from the drivers side of the engine. If I pulled that cam cover, just for grins, what kind of gaskets are they? Can that side be easily removed?