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Knocking 4.6 From Hell

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firebirdtony

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Discussion starter · #1 ·
Hello everyone i got a big or small problem wihth my 00 gt.

at 2k i get this tapping noise at the back of my motor. it only does this when the engine is warm and only tapps in the 2k rpm range. not at idol or at 3k and above.

i have checked the timing chain, its brand new and tight.

i checked the lifters, replaced all 16 and still the tapping.

i pulled the fuel injector plug on the n0.8 plug and the tapping stoped. i reconnected the fuel and pulled the spark and it stoped on 8 only!

i have heard rod knocks and crank knocks but this seams to be not the issue, although the chiltons manual says that pulling the spark tells if the rod is bad. i have put 10k on this motor thrashing it into submission, and a rod would have long come thru the block with what i put it thru. i even sprayed 250 shot of juice on her and its still holding up. just tapping only in the 2-2500 range.

what else could make the no8 cylinder tap like a sewing machine? its more of a ticking than a knock, like valvetrain noise.

i cant keep pulling up to chevys with this god awful tapping. any advice?
 
#2 ·
I had almost the same exact issue as you where the knock would start at only around 2000 rpm. The only difference is mine went away under heavy throttle I don't know if yours does too. It turned out to be a spun rod bearing so I know you don't think that's what it is but its sounds a lot alike. I got a video of it if you want to compare
 
#3 ·
Perhaps it's the infamous head tick. I wouldn't be surprised if you spun a rod bearing, especially after you gave it a 250 shot.

By the sound of it, you're pretty much beating on it constantly, so don't be surprised when something breaks : )
 
Discussion starter · #4 ·
the ticking is on the top side of the motor. i used a stethascope on the bottom, the front cover. and narrowed it to the no8 cylinder. i put the 250 shot on it to kill it and get it over with but it wont die.

ive been driving this car over 10k miles like this. out of town every where. and it runs like a charm. i have no drops or spikes in oil pressure, compression test good. just dont know where else to go if it was a spun bearing it would have long been done.

ive tried oil additives, checked exaust, would a lean fuel on 8 cause it to tick? when i unplug the fuel it stops ticking.

im ready to put a chevy in it and make it a strip car.
 
Discussion starter · #6 ·
which bolts do you refer too? it dont have lifters. the cams are all tight.

but the ticking stopping when cutting fuel or power has got to say something about that cylinder. maybe fuel or something.
 
#7 ·
Well, if you have the head tick, it's caused from overheating. I believe there's a writeup about that one somewhere and if I remember correctly it's not a terribly difficult fix. I saw it last week.

Of course, I doubt much that "fix" will correct any damage that may have already been done.
 
Discussion starter · #8 ·
FluffyTheRhino said:
Well, if you have the head tick, it's caused from overheating. I believe there's a writeup about that one somewhere and if I remember correctly it's not a terribly difficult fix. I saw it last week.

Of course, I doubt much that "fix" will correct any damage that may have already been done.
Click to expand...
i think i see what you are talking about. thanks for the tip i see now its the heads. when i isolate the cylinder on the left head it stops. i guess i will build a bad ass set of heads and put them on. mabe even beef up the bottom end. or just buy me a 4 valve motor and drop in . they say the motor will run as is with no problems. the tsb says its valve guide wear.

NOTE: THIS REPLACEMENT CYLINDER HEAD WILL NOT IMPROVE OR REDUCE PERFORMANCE.



In order to diagnose noise, the following items must be checked.

Verify noise by placing a stethoscope on the back of the left head near the exhaust ports.
Verify that the noise is heard in the left side exhaust system (left side wheel well or catalytic converter, from underneath the vehicle).
Try to isolate the noise by canceling the cylinders, by unplugging the injectors one at a time (start with #8 cylinder). Verify that there are no exhaust manifold leaks.
Check to make sure that the camshaft spacers are in place. If not, install cam spacers (per Workshop Manual Section 303-01C) and retest vehicle.
Check for proper cam sprocket bolt torque, retorque to spec listed in the Workshop Manual Section 303-01C.
Check for spongy lash adjusters (refer to Section 303-00 in the corresponding Workshop Manual).
Verify that the timing chain tensioner pin has been removed.
If the above diagnostics does not eliminate the noise while the cylinders are cancelled, and the engine was built prior to 11/1/2002, replace the left side cylinder head and cam assembly with Part Number 3R2Z-6049-GA. Refer to Workshop Manual Section 303-01C for cylinder head replacement procedures.
 
#9 ·
hmmm, I was gonna say detonation but I dont know, my friend told me he had it once and it sounding alot alike.
 
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#11 ·
Could be piston slap.........that would be my guess......

"ED"
 
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Discussion starter · #13 ·
found out its a worn valve guide. it ticks from 2k to 2k5 then its stops when im in a good power rang. it had to do with the no.8 cylinder colant as described above. detnation is not good. thanks for the input guys. i promiss not to turn it into a car thats ford tough built with with chevy stuff. lol!
 
Discussion starter · #14 ·
well after spraying the car and ramming it through the gears she finally gave up the goose. the 4.6 that wouldnt die- died on new years day 2010.

im going to install a 3v 4.6 out of a newer mustang gt. will post photos of the swap along the way as i get started.
 
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firebirdtony
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