Engine noise diagnosis help - knocking / tapping

[speedosack]

I have this tapping knocking sound that's driving me crazy. The sound only comes under light load while driving. Goes away at idle or under moderate to heavy load. The noise does not correlate with RPM's but when I let off the throttle it goes away immediately. It comes at a fairly narrow range under light load at 10-30 MPH. The knocking noise isn't there with car in park.

HELP b/c this knocking noise is driving me f*cking nuts.

It's not:
a)Turbo cover
b)Exhaust shields
c)Intake components
d)Flex plate bolts
e)Torque converter cover

 

[scottyb]

Check your intercooler shroud bumping against the sway bar.

 

[Just a Six??]

Its not from inside the engine? Never repeats at same RPM? I had rod bearing that seemed ok by eye but at 2200 RPM it sounded like a marble in the engine.

 

[turbo nasty]

Have you checked the flywheel for cracks?

 

[speedosack]

I don't want to drop the tranny unless I really have to. Where would flywheel cracks show up- near the flex bolts or near the crank bolts.

 

[scot w.]

I don't want to drop the tranny unless I really have to. Where would flywheel cracks show up- near the flex bolts or near the crank bolts.

Cracks on the flywheel? Check around the bolts to the crank AND the bolts to the converter.

BUT you really need to determine if it's a internal knock or not before you go chasing a noise all over the car.

Scot W.

 

[speedosack]

Calling all cars.

I was hoping someone out there had the same problem and could tell me what they did to fix it. With 20,000+ GN's and T-types out there I am sure plenty of folks have had this same problem. Plus, I really don't wanna reinvent the frickin' wheel here.

I will check the swaybar/intercooler issue. I'll check the flywheel more closely. After that it's popping of the valve covers to see if the pushrods are rotating. Beyond that, f*ck it, I'll live with the noise unless it gets worse. Cranking up the AC/DC makes ALL the noises go away.

The noise, while annoying, does not seem to affect performance at WOT.

 

[FreeBoost]

If it won't go force it, if it breaks it needed fixing anyway.

 

[chrisgarrett]

Use a stethescope to listen to the engine, trans, alternator, cam sensor, crank sensor, etc. They can really zero-in on noises.

 

[speedosack]

Put an order in for a stethoscope. The problem is not the flywheel bolts, cracked flywheel, or the intercooler rubbing.

 

[TurboV]

any luck?

 

[DailyDrifter]

If it won't go force it, if it breaks it needed fixing anyway.

How true.

Try to see if someone in your area can go for a test drive with you.

 

[bmackinnon]

Make sure the balancer bolt hasn't loosened up and the balancer isn't walking off the crank..... pretty common occurance on TR's and can do VERY expensive damage to the crankshaft snout. First tapping is the reluctor ring hitting the crank sensor, continued operation results in a single, much louder 'tap'

 

[TurboBuRick]

Under light load while cruising?

A bad u joint or a chipped gear in the rear end.

 

[8UWITH6]

My WE4 has a ever so slight tapping noise at certain throttle angles and low speeds while making a turn. For instance, pulling out of a parking lot onto the main road. It sounds like a lifter, but its only within a certain RPM range, its not very loud, and like your problem, does not seem to affect WOT performance at all..................and goes away when I give the car more throttle or let off............ its almost like its harmonic...........

Does this sound similar to your issue speedosack?

 

[TurboMonte 2]

I was hoping someone out there had the same problem and could tell me what they did to fix it. With 20,000+ GN's and T-types out there I am sure plenty of folks have had this same problem. Plus, I really don't wanna reinvent the frickin' wheel here.

Surely you must realize how difficult it is to diagnose ticking, clicking, tapping, knocking (and seemingly randomly variable at that...) with one's audio interpretations and verbal descriptions of such, over the Internet.

Pls don't loose patience with us here & "throw the baby out with the bath-water"--or bite the hands that are trying to give you "free advice/ suggestions".

BTW, flexplate cracks (typically around the crank bolts) are very difficult to see, and a LED-type light (even on a flexible extention) is a BIG help...

Perhaps someone in your area can lend add'l eyes/ears, seat-of-pants...

 

[speedosack]

Ordered the stethoscope 10 days ago, it hasn't come yet.

The noise sounds like it comes from the rear of the engine on the passenger side. Worse when cold. I noticed that the tapping does not go away as the RPM's go up- the tapping is much harder to hear since all the other engine noises get louder.

Checked the flex plate with a flexible white led light-I can't see any cracks.

I'll check the harmonic balancer bolt, I guess I have to remove the pulley? This area was actually my first idea...the noise really sounds like the camshaft / timing chain is being driven forward and taps against the timing cover or the crank is pushed forward and smacks against something. Makes sense since the noise goes away under heavier load- I believe the heavier loads are "seating" the tapping surfaces. Does this sound familiar to any of you 3.8 turbo folks?

Anyway, this is an engine noise of some sort, I am convinced of it.

 

[TurboMonte 2]

You should be able to gently pry/jiggle both pulley and/or harmonic bal'r to ck for any unusual movement--w/o actually removing pulley...

It's hard to imagine how these crank/ balancer end bolts come loose--being originally torqued to over 200ft-lbs?? I would guess its just wear of "stuff" between bolt head & crank threads and/ or stretch of the bolt itself...?

quien sabes?

 

[DailyDrifter]

Ordered the stethoscope 10 days ago, it hasn't come yet.

.

Get a long screw driver and put your ear to the end of it. BTW autozone, sears should have steth's

 

[forcedfedv6]

Ordered the stethoscope 10 days ago, it hasn't come yet.

The noise sounds like it comes from the rear of the engine on the passenger side. Worse when cold. I noticed that the tapping does not go away as the RPM's go up- the tapping is much harder to hear since all the other engine noises get louder.

Checked the flex plate with a flexible white led light-I can't see any cracks.

I'll check the harmonic balancer bolt, I guess I have to remove the pulley? This area was actually my first idea...the noise really sounds like the camshaft / timing chain is being driven forward and taps against the timing cover or the crank is pushed forward and smacks against something. Makes sense since the noise goes away under heavier load- I believe the heavier loads are "seating" the tapping surfaces. Does this sound familiar to any of you 3.8 turbo folks?

Anyway, this is an engine noise of some sort, I am convinced of it.

Dowmpipe hitting the frame or exhaust rubbing somewhere, good luck and keep us posted what you find out.