LT1 knock

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Sep 11, 2016 | 05:36 PM

Aussie420

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LT1 knock

Hi guys, im new to this forum and new to using forums so please forgive me if i've posted this wrong or in the wrong place.

I need help fast. I just installed a new opti on my car and it ran great. Got excited and took it out on the road and drove the **** out of it. Ran a nice hard pull on a straightaway and bam... Loud rattling/knocking noise began right as i was about to shift at ~5750rpm. My guess is its a rod/main bearing but i want to be sure its not valve train before i try to sell it.

Any help is appreciated. Thanks

Sep 12, 2016 | 10:08 AM

SS RRR

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From: Jackstandican

A deep sounding knock can be associated with rotating assembly. Light metallic ticks are usually associated with valvetrain.

Sep 12, 2016 | 12:57 PM

shbox

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From: Little Rock, AR

Post video/audio to get a good opinion.

Sep 12, 2016 | 02:49 PM

BALLSS

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are there any metal flakes now in the oil???....look at the dipstick

if this is a stock bottom end motor....shifting at "5750" is on the high side of RPM

Sep 12, 2016 | 07:40 PM

Aussie420

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As far as i know bottom end is stock. Does have a mild cam though. It does sound like a heavy knock to me but i will post a video to see if you guys can identify it. I appreciate the replies

Sep 12, 2016 | 08:19 PM

Aussie420

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Video

here is a video. Also some smoke coming from passenger side...could be oil i dripped onro headers yesterday not sure.

Sep 12, 2016 | 08:27 PM

CamOnlyJabroni

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From: Fort Wayne, IN

That almost sounds like maybe a push rod broke or rocker arm jumped off. Oil pressure looks good still. Pull that driver side valve cover and check your rockers. Check the other side too if that side is ok.

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Sep 13, 2016 | 06:39 AM

shbox

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From: Little Rock, AR

I think it sound more serious than valvetrain, but you should check it first. Flywheel interference can also make a nasty noise (if anything recent has been going on in that area).

Sep 13, 2016 | 09:29 AM

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cookseyb

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Sounds like the ring gear is hitting the dust cover, run over any speed bumps lately?

Sep 13, 2016 | 09:52 AM

#11

SS RRR

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From: Jackstandican

Sounds bottom end'ish. Check the flywheel/flexplate as suggested.

Sep 13, 2016 | 07:39 PM

#12

Aussie420

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Didn't have time to pull valve covers today, but i did put an infrared temp gauge on the headers and the 2 rearmost ones (closest to firewall) were significantly colder than the rest. Also drained the oil and found small glitter sized metal shavings (some were slightly bigger) these were gold in color. I read somewhere that rob bearings, crank bearings, and cam bearings will all show gold flakes in oil. This leads me to beleieve that it could be a bearing but i need to be sure before i sell it lol.

Sep 16, 2016 | 08:42 PM

#13

NewOrleansLT1

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Pull the valve covers...

Sep 17, 2016 | 11:29 AM

#14

BALLSS

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Quote:

Originally Posted by ******

are there any metal flakes now in the oil???....look at the dipstick

Quote:

Originally Posted by Aussie420

. Also drained the oil and found small glitter sized metal shavings (some were slightly bigger) these were gold in color. .

....well there is your answer.

Sep 18, 2016 | 02:19 PM

#15

Aussie420

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Quote:

Originally Posted by ******

....well there is your answer.

so you think its a bearing forsure? Thats my guess but i wanna be sure... Pulled valve covers today and all looks good. But the thing that is weird is that the back 2 headers are colder than the rest

Sep 18, 2016 | 02:23 PM

#16

hrcslam

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The knock rate says bottom end to me. Top end clicking/knocking will be half RPM speed.

Sep 18, 2016 | 02:27 PM

#17

hrcslam

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Quote:

Originally Posted by Aussie420

But the thing that is weird is that the back 2 headers are colder than the rest

Those could be running rich (less air), due to their location to the TB at part throttle and at idle if the TB blades aren't set correctly. Could also be where the rods are knocking.

Sep 18, 2016 | 04:11 PM

#18

Aussie420

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Just pulled one if the plugs on the cold cylinders and the porcelain around the electrode was just flopping around... Compression is good on that cylinder