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Old 04-04-2004, 10:30 AM
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engine nock in low end

i have a crate 350 with 112 miles on it, 2 says ago it started nocking so i thougt maybe a rod or a rocker arm but those are all ok. listening to it more its coming from the low end, i have a warrenty on it but i dont really want to have to pull the motor and take it back
what might the problem be

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Old 04-04-2004, 12:46 PM
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I would call the company you bought it from and tell them what is happening. Go from there as far as if you should pull it or not.

Adam
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Old 04-04-2004, 01:26 PM
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You may want to recheck ypor torque converter bolts and your harmonic balancer for problems, these can fool you into thinkimg its the bottom end thats bad, Good luck amd post what your experience turns out to be. A lot of us still screw motors together under the old shady tree because we would hate to have to deal with a company rep on a nosy crate engine claim. Anyways you might want to post if it gets worse with engine rpm or if its oil pressure related. Also want o let you know the Sleeve himself got ffoled once by a oil pan that I dented during moving and the crank would scrape against it Just my 2 cents Good luck lemme know what winds up!
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Old 04-04-2004, 02:37 PM
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Noises!

Hi!

Doc Here,

You Did not describe the noise you are hearing, So It's kinda hard to tell what area to look.

As you may know,

Rockers make a Higher "Click" or "Clatter" and usually you can tell right away where the noise is coming from.

Rods, Make a pronounced "KNOCK" deep sounding, and may change under acceleration, (even out the thrust, knock goes away) and may or may not affect oil pressure, (flutter)

Piston wrist Pins will create a mid-range "Double-Knock" as the Pin slides side to side.

Main Bearings Will make a Low Toned Rumble, usually associated with (But not always) Low Oil Pressure. Also associated with engine speed and torque.

You didn't Specify Exactly where you heard the noise, To Isolate it, If you don't have one, get a stethoscope at your local auto parts supplier, or in a pinch, you can use a 3 foot stick.

Run the engine with the knock in evidence, and starting from the front, top put your stick or scope probe on the engine and listen. As you approach the offender, It will become much louder
(You'll be surprised how much louder your engine sounds through a stick!)
Where it becomes the Loudest, is where the problem exists. Then figure out what may be within that area, and eliminate it or include it if you can.

My Experience on my Vette of things that go" Knock "in the night, and can make some real scary noises...and may prove helpful,

Header Leaks....(usually though you can find these right off)

Defective Water Pump...Bad bearing, or something dropped inside it during assembly. This Will sound EXACTLY like a rod bearing.

Defective Harmonic Balancer.. If it's a used one the Rubber may be shot, you can check this with the engine off simply by rocking the belts back and fourth it will knock. At Idle, sounds like the lower end is about to barf.

Any loose or Warped drive pulley.

Debris in a Cylinder ....May have dropped a screw or nut in the induction system when installing The Engine or when assembled at the supplier (This is a Baddie, find out right away)

Fuel pump Rod (if you are not using the mechanical pump) The rod when installed by the supplier is inserted with a "Hold Down" bolt through the side of the block to keep it from falling out. If this is still tight, it will make all kinds of noises Through the cam , and usually bends the rod (A bear to get out after)

Improperly Shimmed Starter, The drive teeth can catch ever so slightly on each rotation of the flywheel and can sound like a knock.

Any Bolt that may have backed off from the flywheel, or torque Converter will make strange sounds depending on what it encounters on each rotation.

Those are some of the basics to look for, If you can eliminate these, Then I'd say It's time to talk to the supplier about a warranty program.

Let me know how it turns out!
Hope that helps!

Doc.
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Last edited by docvette; 04-04-2004 at 02:42 PM.
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Old 04-04-2004, 06:57 PM
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today i got the engine real hot almost 260 leting it idle because i talked to a guy and he said i had an air bubble in my lifter
i drove it and the problem has seem to go away
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Old 04-04-2004, 07:02 PM
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i can't see a lifter causing your motor to overheat.
if your knocking is gone look into your cooling system.
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Old 04-04-2004, 07:05 PM
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i was letting it idle in my driveway listening to it thats why it got hot
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Old 04-04-2004, 07:05 PM
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Hey DocVette......you've been listening to engines a bit too much .........but then again that's a good thing......right?

Mike
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Old 04-04-2004, 07:06 PM
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overheating a fresh motor is veddy veddy bad. i know from experience
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Old 04-04-2004, 11:12 PM
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Quote:
Originally posted by Nightfire
Hey DocVette......you've been listening to engines a bit too much .........but then again that's a good thing......right?

Mike
You betcha,

After 35 + years of building, racing, and barfing engines on the strip, you tend to get a "Tuned" ear.

I have a collection of bent parts I keep to remind me what noises are trying to tell me....

And yes...I have been listening to engines a bit too much,

My Ex will agree with you...After 12 years of marriage she could only identify me as a "Butt hanging out of a hood"

As She said, "You love that darned Car more the me, Huh?"

I replied "The Thing that attracted me most to you (other than the obvious) Is your astute grasp of reality..."

Luckily, The Courts didn't consider my Vettes As Community Property.

Doc

Quote:
Originally posted by digitalfrek
i was letting it idle in my driveway listening to it thats why it got hot
Your Car Should not overheat no matter How long you let it Idle, You need to look into that.

I just got through Vacuum checking the engine and headlight doors on 2 of my Vettes, This required Several hours of idle, while tracking down leaks. At best long run time with short shutdown (which causes heat to rise) and restart ... Never got over 190-200 degrees.

Check your cooling system.

Doc
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Last edited by docvette; 04-04-2004 at 11:12 PM.
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Old 04-05-2004, 10:29 AM
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Well don't worry too much. If its a piston (which would only have broken its skirt if you reved the crap out of it) it will make a hollow double knock.

Rod knocks are unmistakable. If you have to ask "is that a rod?" its not. A rod sounds like somebody hitting a wal-mart special tin trashcan with a ball bat. You'd know, trust me.

Main knocks are a little softer and hollow, follow RPM but are harder to hear as the RPM raises. Usually only get them with a warm motor.

Hope that helps.

K
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