Bad noises ... with video

jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
I now have just under 50 miles on the rebuild, and plenty of idling and dyno time before that. Today, about 15 minutes into driving it, it starts making a noise at idle (along with occasionally stalling if left in drive when sitting at a light or what have you). The best way I can describe the noise is that it sounds like I dropped a handful of sockets into the oilpan before I started the truck. I checked paticularly if it's correlary to RPM, all I noticed is that it goes away above 1100 RPM (you can see this in the vid when I rev it). Anyway, here's a video with the sound.

Click here to see Video

Anybody know what could cause this? AFR numbers are good and I was getting no knock until my datamaster died.
Ideas:
-starter not disengaging (checked, works fine)
-One of the power accesories has a bad bearing (pulled the belt, if anything it got worse)
-Bad lifter (should hope not, they're brand new)
-Loose TC / Flexplate bolts (pulled the cover, everything is tight)
-Header / Downpipe knocking frame (checked, no visible movement)
Also am thinking possibly bad TC, but I'm not so sure how to tell, it feels fine driving. The noise seems to be coming from the lower rear of the motor but no way to tell for sure
 
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jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad noises ... with video

gjp said:
do you have a cat???
Click to expand...
yep, I have the PTE high flow 3" cat ... the heat shield on the body is long gone. Can a cat make that noise?
I'm desperate to figure out what this is, I'm afraid to even run the truck it's so noisy ... And I'm supposed to get it inspected monday :(
 
gjp

gjp

another post whore
Re: Bad noises ... with video

if the ceramic on the inside is broken it could. Get a rubber hammer and tap it. Not to hard. See if you hear anything. I cant view the video so I am not sure of the noise.
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad noises ... with video

gjp said:
if the ceramic on the inside is broken it could. Get a rubber hammer and tap it. Not to hard. See if you hear anything. I cant view the video so I am not sure of the noise.
Click to expand...
It's not coming up? Worked for me :dunno:
 
gjp

gjp

another post whore
Re: Bad noises ... with video

now it did. Wow thats loud. Hmm.... could be a loose flywheel bolt..but you checked that.
 
C

Captain Morgan

Moderated User
Re: Bad noises ... with video

wow, that sucker sounds like a Jiffy Pop!! :eek:

Here's what I would do if it were me. Since you seem to be covering the obvious things going from lifters to converters, I would suggest jacking the front end up either on stands or put it on ramps, fire it up and see if you can isolate where the sound is coming from the loudest.

If you have a long heavy screwdriver, you can put the tip of it on various places on the engine and put your ear to the handle to help determine where the sound is coming from.

Actually, before you even fire it up again, pull the oil pan drain plug and get a sample of fluid, about a cup or so I guess. See if theres anything in it that shouldnt be. If that seems ok, then try to isolate the sound.

Another thing I would do (some my not agree with me here) is to disconnect the torque converter bolts, push the converter that 1/4" back onto the trans and fire the engine. If the noise stops or it changes, you'll know if its the converter, something in the bottom end of the engine or the problem exists somewhere else.

If none of this seems to be getting you any closer to finding the problem, try pulling the spark plugs and make sure there's nothing screwy going on there. Its easy enough to check and gets another thing off the list.

I hate to say it, but if you still cant figure it out from there, you're most likely gonna have to drop the pan and check some things out. Could be something like the oil pump binding up or something, who knows.
 
nallj92

nallj92

Active member
Re: Bad noises ... with video

did you use a hand or a sethescope to feel where its coming from? you sure in the oil pan or the heads or what? narrow down if it from valve train or lower end,, sounds like lower end to me
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad noises ... with video

nallj92 said:
did you use a hand or a sethescope to feel where its coming from? you sure in the oil pan or the heads or what? narrow down if it from valve train or lower end,, sounds like lower end to me
Click to expand...
Morgan - already pulled a plug, they look A+ still, nice clean insulators and just a little carbon. By hand there's no vibration in the lower end, by ear it sounds like it's in the lower end. The noise is actually loudest inside the truck, which makes me suspect the converter. I will try both disconnecting the converter and the screwdriver listening methood tomorrow. ... also will check the oil. Thats the only fluid that I haven't had a major leak from a loose fitting in yet :roll:

also, oil pressure has been beautiful the entire time, but I suppose we can't eliminate the pump just for that ... getting an early start tomorrow so you'll be hearing from me
 
HotRodV6

HotRodV6

Doghouse Member
Re: Bad noises ... with video

WOW, thats loud, i thought the small amount of cold start knock my engine made was bad.

Id say if its still there when the TC is unbolted then its definatly in the bottom end.

How much OIL Pressure are you making at idle?

Maybe check for a broken or cracked flexplate?

Id have to say that unfortunaly your probably going to have to pull the engine and pull the oil pan to find the problem,

Oh wait, when you installed the oil pump pick up screen did you weld it to the pump body?
If nopt its not un heard of for them to come loose and fall off and might be getting hit by the crank, my buddies 4.3 blazer had that happen after he rebuilt the motor.
 
Jimmy

Jimmy

Banned
Re: Bad noises ... with video

Ugh,that sounds bad.

Make sure the bendix isn't grinding on the flexplate.
 
ghettosled

ghettosled

SYTY SUPERSTORE
Re: Bad noises ... with video

i havent seen your video (i got no sound) , so i can be way off here, but are your lifters staying pumped up and oiling the rockers enough at low RPM? usually rod knock, or loose converter bolts/flexplate will stay loud if not louder with more rpm.
 
C

Captain Morgan

Moderated User
Re: Bad noises ... with video

doesnt sound like lifters at all really, and when the truck shuts off, it almost sounds like theres 1 more "pop" or "ping" that happens (aka, something still spinning after its turned off)
 
ViciousV6

ViciousV6

400HP/550FTLB
Re: Bad noises ... with video

Check the flywheel clearance on the starter nose, i just had an issue like that would come and go, and then my tranny guy was going to pull the tranny to redo and discovered that the flywheel was flexing just enough some time to contact the appendix on the starter. It wasn't as loud but that surely sounds like a rotating gear contacting something.

Hope this Helps.

Ralph
ViciousV6
 
Teeleton

Teeleton

Non-Boosted
Re: Bad noises ... with video

I would also say that it sounds like the flexplate could be loose. Not so loose that you can move it by hand, but take a large flathead screwdriver and put it in the converter next to the bolt. Use it like a prybar and see if you can move the converter either direction. If it moves at all, you need to retorque the bolts. For some reason, with the cam lope and hard shifting that my blazer does, it seems to loosen the torque converter bolts about once a year. The dead giveaway when I suspect it's happened on mine, I'll put it in park and stab the throttle, let the revs get up to about 4k, then get off of it. As the revs come down it'll make a rattling noise. Yours sounds like its too loose already, so I would just slide under it and try to move it with the screwdriver. If it's the flexplate hitting the starter (I also had this problem when I installed my latest starter), you should be able to put the truck in reverse, and stall it up. The stall will balloon the converter and flex the flexplate into the starter nose (making a fairly horrible grinding noise) if that's your problem. Starter shims really don't help with forward/back adjustment of the starter. Since mine is an aftermarket gear reduction unit, I had to contact the manufacturer, and they sent me a shim kit (free of charge w/ no shipping cost!!) to install between the bendix and the gear unit to draw the starter gear into the gear reduction body a little bit.

Teeleton
 
Robert Lone

Robert Lone

MUTANT
Re: Bad noises ... with video

jj,

I have heard this exact same noise on 2 other occasions. '76 TA and my Father's Suburban. Both times the center of the flexplate was broken out of it. The truck still starts and runs fine and until you pull the transmission out you can't see it.

If you don't find anything else, take a look.:2cents:
 
Ian Turgeon

Ian Turgeon

Cascading Inspiration
Re: Bad noises ... with video

My loose converter bolts sounded exactly the same, didnt make the noise while it was running though, just changing into gear/reverse or at startup/shutoff.

Good luck, hope its something simple so you can be on your way.
 
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