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

LT1 knocking help. Video Inside!

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Old 04-08-2010, 01:08 PM
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Default LT1 knocking help. Video Inside!

Well guys, i have 127k miles on my bolt on lt1. Just drove it home from work last night (6 miles) and it started knocking when i started it. I noticed something wasn't right yesterday but it wasn't loud untill the drive home. Noise is coming from the passenger side valve cover for sure. My cousin thinks the valves need adjusted. He has worked on multiple 350 engines from being a star demo derby driver. I have no idea what it is, but it sounds like hell. He thinks we can remove the coil pack driver side and pull off that valve cover easily. Looks like we may be able to get off the pass side valve cover without removing the alternator?? Can i get a step by step on what to check? I printed out the adjusting valves and zero lash from here http://shbox.com/1/4th_gen_tech2.html#adjust_valves

What do you think the knock is and how much to fix this (if we can do it myself hopefully?) I know the front main gasket needs replaced because i have a small oil leak. Figure it's going to be in his shop for like 2 weekends anyway. I would really like to do heads/cam some day if i don't get rid of the car but i don't know how much more we would have to pull off to do so or how hard any of that is. Guess i'm just trying to get a starting point and advice/tips on what the knock is and how and how hard it is going to be to adjust the valves. Any info would be awesome! Here is a link to youtube of the engine at idle (cold engine, but doesn't go away when warm)
http://www.youtube.com/watch?v=fR3uQI6cYp8
Old 04-08-2010, 01:16 PM
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that gonna need alot more than adjusting valves, thats a rod knock
Old 04-08-2010, 01:59 PM
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x2 what he said ^.. Doesn't sound good at all.
Old 04-08-2010, 02:00 PM
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You need a rod adjustment.
Old 04-08-2010, 02:29 PM
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Pull the VC and check over all the springs, rockers etc. It could also be a bad lifter. All those are easy fixes. If its not any of those your motor is shot, but that usually has a deeper knock/thud IMO.
Old 04-08-2010, 02:48 PM
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I don't know about it being a rod knock it sounds like a bad lifter. Hearing how it stoped for a second and then came back, rods don't stop knocking. lifters will if the get stuck. Easyiest way to tell is take the time to pull the valve cover. Start the car with the valve cover off and see if you figure wich one is making the noise. You may be able to find it as soon as you pull the valve cover. If you verify its a lifter you can pull the intake and replace the lifters, and pushrods this weekend and be back on the road.
Old 04-08-2010, 02:49 PM
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at 12 secs, did the motor stop knocking or was that just the camera ?
Old 04-08-2010, 02:50 PM
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spun bearing, engine is gone.
Old 04-08-2010, 04:23 PM
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I'm gonna say check the lifters. you can hear still hear the car running in the video when the knock quits for a bit.
Old 04-08-2010, 04:26 PM
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That's rod knock. Bye bye motor. Usually valvetrain issues is more of a tapping - I'm hearing a THUDDING.
Old 04-08-2010, 06:27 PM
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Originally Posted by RamAir95TA
That's rod knock. Bye bye motor. Usually valvetrain issues is more of a tapping - I'm hearing a THUDDING.
I was thinking just the opposite. I just fixed a stang with a bad lifter and it sounded just like that. When Ive thrown rods its a much deeper thud and sound much deeper in te block. Anyways Id start with the valve train first and pray.
Old 04-08-2010, 07:59 PM
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could be anything prolly doesnt help. but it does sound closer to the top then the bottom to me.
Old 04-08-2010, 08:46 PM
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Wow thanks for the help so far guys, to answer the questions the knock does stop every now and then especialy as soon as the car is started, it wasn't the camera. So what i'm assuming i'll do is pull the valve covers. do i need to remove the alt. or anything else? and should i check the driver side while i'm at it? And i'm assuming if a lifter and or rod is bad i should go ahead and replace all of them? Decent brand name that won't kill my wallet? thanks so much and i hope i get some more replys!
Old 04-08-2010, 08:52 PM
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Toasted.

I will bet rod and the crank could still be turned if it was only 6 miles and that short video run. If you run it much more add crank to the list. I will guess block is still ok but running it more could get a main.

Check valves first. I doubt it is lifter, but without hearing it in person could be a lifter or ro just seems rod is more likely.

Good luck
Old 04-08-2010, 08:53 PM
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easiest thing to do first is check the lifters and hope. if you dont see anything, try putting a heavier weight oil in the car and see if that stops the knock, if so its a rod.
Old 04-08-2010, 09:03 PM
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That motor is fugged. Either a main or rod bearing. No chance in France of that being a lifter.
Just plan on pulling it out.
Old 04-08-2010, 09:07 PM
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I would suggest that you don't crank that thing any more. Start by pulling the valve covers. If you don't find anything pull the intake. After that it's time to drop the pan.

Keep running it and it will go BANG.
Old 04-08-2010, 09:11 PM
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Originally Posted by GIZMO
I would suggest that you don't crank that thing any more. Start by pulling the valve covers. If you don't find anything pull the intake. After that it's time to drop the pan.

Keep running it and it will go BANG.
...and ruin the crank beyond repair.
Old 04-08-2010, 09:21 PM
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That's a spun bearing, right where it always happens #2 cylinder. Your engine isn't shot. You will need a rebuild though. Do not run the engine anymore, take it to a machine shop.
Old 04-09-2010, 12:04 AM
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That sounds loud to be valve train, anything is possible though.

Take everyones advice dont run the engine!


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