Community Forums

terry735001 · 08-18-2018, 03:47 PM

so its nice to say hi to every 1 again . its been some time from my last post

In the end i think i have some thing that even i cant seem to find or fix. its making me so sad that i cant find it

so when under hard load or WOT i get just for a sec a tapping sound from my motor only when in drive with load on the system and only when at running temp of 195f

all so when driving at 55 to 45 mpr its tapping alot . not some thing i can over look

sound is coming from top end only behind the throttle body on left side of motor but is very hard to track down. when it started i was on a trip and it still made it home from 400 miles trip like nothing was wrong

no sounds coming from trans or back of motor / flywheel

for the last month i have been trying to find it . tried all kinds of things . stick to ear all over the motor . dropped drive belt to make sure its nothing on the front of motor .

pulled intake looked at all hydraulic lifters and pulled them all the way out to look at rollers on end

pulled valve covers too

pulled oil pan and pulled all caps and manes all looked good and looked at piston pins as good as i could from below and looked for piston slap and every thing looks good

no codes in ECM

new spark plugs

coils have a good jump of spark to them

wires tested and look good as there not that old

pulled both cam and crankshaft position sensor both looked good with nothing on them

both O2s and MAFS and knock sensors show ok on obd2

pulled all 8 fuel injectors and tested them under test stand and moved them around to see if tapping moves . same with coils .installed new fuel filter and fuel pressure regulator

hold 175 to 180 psi compression test on all 8

i can not get mode 6 to come up on my obd2 so i cant see if there is any real time misfires

it sounds like a spark knock or some thing with timing

just tried seafoma and marvel mystery oil

what i am left with

throttle body makes some sound knocking sound when i had it off . its well used

coil and wires could be dropping out under heavy load

fuel psi tester well be coming in soon . had to order 1

could have bad fuel on last stop so been running out as much as i can when testing and well dump 93 in latter to see if it helps

cam and timing Chane out of spec

i have seen some funny stuff on exhaust manifold some how making a tapping sound after getting hot

i cant find any video of any other kind of motor making this sound

its coming down to just dumping high cost parts at it so i would like to see what others think on where to start

GREGORYJ · 08-18-2018, 04:32 PM

Years ago a friend had a 318 Dodge V8 that had a tapping sound that sounded exactly like a valve lifter. After many weeks of looking and changing parts, it turned out it was a leak in the exhaust manifold. I believe one exhaust manifold bolt was broken on one side.
It sounds like a difficult problem to find, good luck. It will be interesting to know what it is when you find it.

M&EM · 08-18-2018, 04:33 PM

You might want see if any clearance issues with radiator fan & shroud sections. Is a/c on or not affecting sound? Leakage at exhaust manifolds?

DobeBus · 08-18-2018, 04:41 PM

Quote:

Originally Posted by GREGORYJ

Years ago a friend had a 318 Dodge V8 that had a tapping sound that sounded exactly like a valve lifter. After many weeks of looking and changing parts, it turned out it was a leak in the exhaust manifold. I believe one exhaust manifold bolt was broken on one side.
It sounds like a difficult problem to find, good luck. It will be interesting to know what it is when you find it.

I once had a car that had a knock. Everybody that listened to it said it was a rod knock. I knew it wasn’t so I kept looking. Turns out it was a cracked flywheel. It had holes in for weight reduction and was cracked from hole to hole. Only one section had not cracked yet or the flywheel would have spun loose from torque converter. It’s worth a look

ktoutoor · 08-18-2018, 08:00 PM

At one time I would get a tapping sound only on hills heavy load turned out to be MAF sensor not metering the air correctly causing spark knock

YC1 · 08-19-2018, 12:18 AM

Bearings in alternators can cause some strange tapping. Might be able to warm it up and then remove the belt temporarily.

Arch Hoagland · 08-19-2018, 03:10 AM

What year make and model? How many miles?

How often do you change oil?

On my 8.1 the exhaust manifolds have made some really strange noises and have had them repaired twice.

Have you replaced the wires yet? I've put plugs and wires in mine twice over 90,000 miles. I use all oem.

Winemaker2 · 08-19-2018, 05:29 AM

Springs on dampener plate can be noisy?

vettenuts · 08-19-2018, 07:22 AM

I think several suggestions are worth investigation including an exhaust leak and MAF and resulting engine knock that can result.

Just want to throw one more idea out there. The Gen III rocker arms on the LS1 were known to lose roller bearing needles resulting in engine knocking similar to a bad lifter. Don't honestly know if this also affected the 8,1 rocker arms, but the designs are very similar. They will eventually show up on a magnetic drain plug if you have one.

Not sure how closely you looked at the rockers but something to file away if you still can't find the source and decide to look deeper into the motor. I would definitely try all the non-invasive things first though.

You might also want to see how true the harmonic damper is running on the crank.

terry735001 · 08-19-2018, 12:44 PM

thanks every 1 last night after posting this i found 1 more thing wrong . A wire on fuel injector 2 ground wire was rubbing on the side of the motor .not 100% of the time but when it was it was dumping fuel into the motor On the 8.1L all the fuel injectors get 12vdc+ at all times and use the ground wire to fire the fuel injectors so with this wire going to ground I tested all wiring on the fuel injectors them self but this was some of the wiring coming from the ECM This is some thing that started 3000 miles ago and just became tapping so i guess this started out slow and may have hurt my motor in the long run i am now running a all new wire

vettenuts · 08-20-2018, 05:56 AM

I would be interested in finding out if that was the fix. Yet more good information to file away in the old noodle

CJ7365 · 08-20-2018, 06:02 AM

Quote:

Originally Posted by vettenuts

I would be interested in finding out if that was the fix. Yet more good information to file away in the old noodle

Yeah would like to for out for sure.

That was alot of work the OP did before finding this injector wire

OP also stated on his obd2 reader does not show active misfires here is where the Tech 2 scanner would of come in handy.

Wonder why the CEL did not light up?

terry735001 · 08-20-2018, 08:51 AM

i wish i had more file size here and i would just upload the video i have of it doing it . tryed to add photobucket pics and videos but i guess you cant any more . no it did not fix it . i fixed the wire and pulled the power on the ECM so it would forget all fuel trims but giving this wire was doing this on and off it could have hurt the motor in the long run and it may take a shop to find and fix it i have taken the video to many reman shops for motors and ruled out alot of things i well keep this post up to date on whats going on

CJ7365 · 08-20-2018, 05:48 PM

If you create an account on You Tube, you can upload it there, and then provide a link.

I hope you figure this out, come back and please let us know what you find out.

If you take it to a shop, i highly recommend that you take it to one that has the Tech 2 scan tool, this will show live data, missfires etc.... ask them before hand if they have one, if they dont know what it is, run away from them.

Here is a link that Kevin did a great video on the Tech 2

http://www.irv2.com/forums/f22/video...is-399995.html