Rattle noise under 3rd gear acceleration

Stanley Bullock

New Member

Mar 5, 2012

12

0

1

Piqua, OH

Mar 5, 2012

#1

• Mar 5, 2012

• #1

Hello guys! new to the site and the 4.6 world.My problem is noise under hard acceleration in third and fourth gear.Sound like valve rattle.Engine has a 164k on it. Dont know a lot about the car, was purchased used off lot . All seems to be in working order,runs very strong except for rattle noise.

 

bhuff30

Founding Member

Dec 11, 2001

6,037

35

129

Olathe KS

Mar 5, 2012

#2

• Mar 5, 2012

• #2

It is very possible the noise is detonation. Try filling with premium next time. If the rattle is softer or goes away completely, you found the problem.

There are many possible causes for detonation, so you will want to track down the reason and/or run premium fuel. Detonation can cause engine damage.

 

trinity_gt

10 Year Member

Jan 31, 2003

3,125

81

99

Canada

Mar 5, 2012

#3

• Mar 5, 2012

• #3

Is it a "marbles in a can" type of rattle?

Try running the tank nearly empty and refilling with premium. It's possible the car has been "tuned" for higher octane fuel and what you're hearing is detonation. I would recommend not beating on it until you resolve this issue as detonation can damage the engine if it's severe enough.

 

Stanley Bullock

New Member

Mar 5, 2012

12

0

1

Piqua, OH

Mar 5, 2012

#4

• Mar 5, 2012

• #4

Yes! it does sound like a rattle can.Thanks for the quick responce time, u guys are better than cops....lol. I'll try the premium gas route,sure hope that does the trick.love the car,would like to keep her, and to bhuff30, my Turbocoupe runs 13.80's bangin 4cyl's and a 5 spd.

 

03_TrueBlue_GT

Active Member

May 5, 2010

810

41

29

Houston, Tx

Mar 5, 2012

#5

• Mar 5, 2012

• #5

Is the car tuned or is it completely stock? Also have you done any maintenance on this car yet? Like changing the plugs, fuel filter, air filter, cleaned the throttle body and MAF?

Doing all of these things should help you out if haven't. Also try running sea foam through the car by pouring a can in the gas tank.

 

Stanley Bullock

New Member

Mar 5, 2012

12

0

1

Piqua, OH

Mar 5, 2012

#6

• Mar 5, 2012

• #6

Only mods i have done are BBK cai, with Trick Flow Upper Plenum, really have not done any Maintenence to her yet. Dont like the idea of sea foam, heard too many nightmares about that stuff. Gonna hook scanner to it and see where timing is tommorow,also go ahead and do some maint. items as well, "wish me luck

 

G

GtVert_00

Member

Feb 23, 2012

32

0

7

Mar 6, 2012

#7

• Mar 6, 2012

• #7

It definatly sounds like deteonation. I asked my gf to fill up the car one day while I ran to the bathroom at the gas station... didn't say to put premium fuel in it and she put 87 in which caused that same noise your describing.

 

bhuff30

Founding Member

Dec 11, 2001

6,037

35

129

Olathe KS

Mar 6, 2012

#8

• Mar 6, 2012

• #8

Stanley Bullock said:

...to bhuff30, my Turbocoupe runs 13.80's bangin 4cyl's and a 5 spd.

Click to expand...

These cars really are impressive, especially for their time. They had premium options, could be modded very easily and really had descent power from the get go. There's something just really fun about a turbo spooling up.

As for the 4.6 problem, these cars don't require premium from the factory. If the ECM has been modified somehow, it may require premium. If your car doesn't have a tune, then you should definately look for the issue. My 97 GT had a rattle in 3rd for a very long time. After I started running E30, the issue disappeared, even after switching back to regular 87 octane. My therory is, that the extra ethanol helped clean up a dirty fuel injector, which fixed the detonation problem.

 

Stanley Bullock

New Member

Mar 5, 2012

12

0

1

Piqua, OH

Mar 6, 2012

#9

• Mar 6, 2012

• #9

Well ! I think i found the culprit. While installing new plugs, i saw that there was coolant.in left bank plug holes,also down inside intake valley. Was hoping it wasnt a cracked intake which i know they"re prone for doing. Lucky me, was just the gasket.
Coolant was getting into 2 & 3 cyl. Plugs were shot (crusty& brown in color). Havent gotten her back together yet, but im sure that was it. Thanks for all your help guys

 

1987stangman

Member

Jul 12, 2006

684

24

19

Mar 6, 2012

#10

• Mar 6, 2012

• #10

If it's a 96', I would really check over that intake good before you put it back on. Back when I still had the bone stock NPI motor still in it I removed the intake to fix the cooland hose thats underneath and 2 days after I had it back together I started smelling coolant and yep, intake was cracked in several spots in the back where the heater hose goes and was letting coolant in the plug bores.