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03 Cobra - Rattling noise from front of engine

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Just recently my 03 Cobra engine has developed a slight noise seemingly coming from the front of the engine. It’s difficult to describe, but it basically sounds like a brief rattling noise which occurs twice per second at 750 RPM (idle). If I raise the RPM’s, the frequency of the noise changes with the RPM, so if I rev up to 1500 RPM, the noise will occur four times every second. If I rev high enough, it seems to go away.

At first I thought it was the belt since it sounded exactly like the belt making two revolutions per second, but the belt seems fine. The only other thing I can think of is that it has something to do with the timing chain, maybe a bad guide, tensioner or chain.

Also, I seem to get a slight whiff of burnt oil shortly after I start the car when it’s cold. It’s almost undetectable, but I’ve noticed it now twice. I checked for oil leaks and found none. Not sure if it’s related, but it started at the same time the noise started. Are the timing chain tensioners on this engine hydraulic, filled with oil and maybe leaking?

The car runs perfectly fine and performs normally otherwise. Not sure if this is a clue, but I don’t drive the car much, so it sits in the garage for sometimes two weeks or more at a time. In winter it sits even more and is only taken out on nice days.

Anybody have any ideas? Are there any known issues with 03, 04 Cobra timing chains or related hardware? Not sure where to even start here.
 

VenomousDSG

Don't Tread On Me
TCG Premium
Apr 30, 2006
20,630
21,946
Yorkville, il
Could be a pulley issue, which these cars are notorious for having problems with the stock ones. You don't have the billetflow upgraded pulleys do you? Even if the belt looks fine too it could still be that, as it expands over time and it will not create enough tension on those picky pulleys.

Just out of curiosity, how many miles are on the car, and have you ever changed the supercharger oil? If you haven't and it has some decent miles on it, that could be the issue. it could be all drying up and thick like molasses and not lubricating the inside of the supercharger.
 

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Ok, here is a short video of the noise where you can clearly hear the knocking. Also, I don't know why there seems to be a loud whirring noise in this video. The whirring noise isn't nearly that loud when you're standing in front of the car. I think it's an anomaly of the phone camera mic.

Also, I checked all the plugs and they're snug.

https://sabercathost.com/4X9z/Engine_Noise.mkv
 

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Yes, Speed Inc. is what I was thinking of, but I checked and they only do GM stuff now.

DMP looks good and is a LOT closer. Thanks for the info Venomous.
I'll give Drew a call tomorrow.

This whole situation is making me sick. I love the car and have always gone out of my way to take very good care of it. This is the first "real" problem I've had with the car in 14 years.

Not sure what could have happened. I drive like a granny and the engine rarely ever sees anything over 3000 RPM.
 

nytebyte

Not Politically Correct
Mar 2, 2004
13,627
20,958
Update: It was the water pump.

I wouldn't think a water pump would make that kind of noise, especially at those intervals, so I didn't check it at first, especially since it's no fun to get to.

New water pump and noise gone. I guess I got all worried for nothing.

I still gotta bring the car to Drew at Dmarkperformance for the transmission issue. I can't seem to figure that one out.
 

FESTER665

TCG Elite Member
TCG Premium
Apr 13, 2008
39,959
66,089
Streamwood
Update: It was the water pump.

I wouldn't think a water pump would make that kind of noise, especially at those intervals, so I didn't check it at first, especially since it's no fun to get to.

New water pump and noise gone. I guess I got all worried for nothing.

I still gotta bring the car to Drew at Dmarkperformance for the transmission issue. I can't seem to figure that one out.

See how my car is coming along when you're there. :bigthumb:
 

boostedguy05

not well known
TCG Premium
Dec 18, 2010
34,180
25,511
See how my car is coming along when you're there. :bigthumb:

dirty mike and the boys took it over.

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