LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Sound diagnosis, knocking?

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Old Feb 3, 2009 | 04:44 PM
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Default Sound diagnosis, knocking?

Well a friends LT1 is making some racket that I can't seem to figure out, please watch the video and let me know what you think. I'm hoping its not knocking, to my knowledge the motor has never been opened up, its got 161k on it, the trans has been replaced, I guess that happened about a year ago? Oil pressure is over 40 psi at 2k rpms, usually steady around 30psi on a warm idle, one time I did see it fluctuate at idle though.

What's this racket?

Let me know if a better video is needed. I've never actually heard a knocking motor and someone who knows what one sounds like so I have no idea what I'm listening for. Thanks -Corey
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Old Feb 3, 2009 | 04:52 PM
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Originally Posted by camar0corey
Well a friends LT1 is making some racket that I can't seem to figure out, please watch the video and let me know what you think. I'm hoping its not knocking, to my knowledge the motor has never been opened up, its got 161k on it, the trans has been replaced, I guess that happened about a year ago? Oil pressure is over 40 psi at 2k rpms, usually steady around 30psi on a warm idle, one time I did see it fluctuate at idle though.

What's this racket?

Let me know if a better video is needed. I've never actually heard a knocking motor and someone who knows what one sounds like so I have no idea what I'm listening for. Thanks -Corey
Time for a new short block...
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Old Feb 3, 2009 | 05:21 PM
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kinda sounds like a rod knock to me...
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Old Feb 3, 2009 | 05:24 PM
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Ive heard a spun bearing, and Im gonna have to agree ^^^^ ;(
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Old Feb 3, 2009 | 06:59 PM
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im sorry... time for a 396?
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Old Feb 3, 2009 | 07:33 PM
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Bummer, now I know what it sounds like. I'll have to let my friend know its going to go eventually. The car(94 formula) has been driven around like this for a while now actually. Hmm no funds in his case for a 396, probably once it goes I'll help him find another stock LT1 to stick in it for cheap. I learned a lot from my motor swap, I think I could do the next one a lot faster.
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Old Feb 3, 2009 | 07:42 PM
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Originally Posted by camar0corey
Bummer, now I know what it sounds like. I'll have to let my friend know its going to go eventually. The car(94 formula) has been driven around like this for a while now actually. Hmm no funds in his case for a 396, probably once it goes I'll help him find another stock LT1 to stick in it for cheap. I learned a lot from my motor swap, I think I could do the next one a lot faster.
i need more friends like you, lol.

How long did the whole process take you? did you roll it out on the tranny and axle?
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Old Feb 3, 2009 | 07:59 PM
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No I did mine out the top. Hard to say as I usually took a lot more time than was needed as I slowly ordered other parts I needed. I'll probably do this one out the top too if he wants to do a swap. Not sure what he will want to do after this news is delivered.
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Old Feb 3, 2009 | 08:04 PM
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If you're going to swap in a whole longblock, do yourself a favor and take it out the bottom.
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Old Feb 3, 2009 | 08:19 PM
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How many miles has he driven it like that for? thats nuts if its anything over like 2 or 300 miles. i cant believe it hasn't put the rod thru the block yet. Tell him to take a loan out for the 383
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Old Feb 3, 2009 | 10:44 PM
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That rod knock sounds exactly like my previous LT1.

You could remove the engine and trans all at once if you drain all the fluids remove radiator, water pump and take the hood off.

Ive always liked taking it out the top, just found it to be fast and easy.
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Old Feb 4, 2009 | 12:31 AM
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I don't know how I'm going to break the news to the wife Corey! You'll have to do it gently! lol. Thanks for all the help guys and thanks for posting it up Corey!
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Old Feb 4, 2009 | 12:31 AM
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Originally Posted by ramair95ta
if you're going to swap in a whole longblock, do yourself a favor and take it out the bottom.
+1000!
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Old Feb 4, 2009 | 05:16 AM
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Originally Posted by Vulcan2422
I don't know how I'm going to break the news to the wife Corey! You'll have to do it gently! lol. Thanks for all the help guys and thanks for posting it up Corey!
No problem Gary, we'll figure something out.

I really didn't have any issues pulling it from the top last time. I honestly have no idea how many miles it has been driven this way, I do know its more than 500 miles though. His wife has probably a 50-60 mile commute round trip for work.
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Old Apr 23, 2009 | 07:04 PM
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Ok as a update, are we sure it is def. knocking? I just ask as his wife beats on this thing, probably put 3k miles on it since posting this up. If its something really bad can you see metal particles in the oil? Going to do a oil change on it I guess.
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Old Apr 23, 2009 | 07:17 PM
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Pull the pan and check and I agree with pulling from the top
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Old Apr 23, 2009 | 07:21 PM
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Sound exactly like my old car did when I spun a bearing.
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Old Apr 24, 2009 | 10:23 AM
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Originally Posted by camar0corey
Ok as a update, are we sure it is def. knocking? I just ask as his wife beats on this thing, probably put 3k miles on it since posting this up. If its something really bad can you see metal particles in the oil? Going to do a oil change on it I guess.
checked the rockers ?
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Old Apr 24, 2009 | 10:39 AM
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Yea, check the oil for sure. Pull the filter and cut it open and inspect that as well. If there is bearing material or metal parts coming apart in there, it'll show up in the pan and filter. Go from there.
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Old Apr 25, 2009 | 05:10 PM
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an easier way to check for metal is to use a paint strainer or even a rag over a container. i always use paint strainers and they will pick out pretty much everything.
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