Rod knock on an engine with 4000 miles??????

[americanmusc1e]

my motor was rebuilt 4000 miles ago and today it started making death noises,
at Idle and anything below 2500 it runs perfectly normal
above 2500 it sounds like a really bad diesel motor and won't rev past about 3000(the noise gets worse the harder you press the gas)

rod knock??? what else could it be????

[americanmusc1e]

another thing to mention is that it only knocks in gear. tried to get it to do it in drive with my foot on the brake but I couldn't get it to rev to 2500 without it taking off. The 700r4 is new, less than a month old. I guess it could be the transmission but it sounds like its further up.

[ZombieWeinerDog]

Originally Posted by americanmusc1e

another thing to mention is that it only knocks in gear. tried to get it to do it in drive with my foot on the brake but I couldn't get it to rev to 2500 without it taking off. The 700r4 is new, less than a month old. I guess it could be the transmission but it sounds like its further up.

clutch maybe? im no expert. keep me updated, im interested

[t&tkennels]

maybe check the torque converter bolts. they can make a pretty bad knocking sound when loose

[paaw]

Also check your flywheel (flex plate) mine was cracked, thought i had a rod knocking

[americanmusc1e]

Ive had a cracked flywheel before, this knock isn't a gentle tapping.
It sounds like someone is banging on my engine with a hammer

[spinning wheels]

Sound travels thru an engine, so it can be hard to pin point what is causing the sound. Use a set of stethoscopes, (you can get them at Harbor Freight real cheap). This can help you pin point the noise better. Just throwing this out there, I have heard of water pumps making the thumping sound. The only time I had an engine make that sound, it was a rod knock

[kdailey4315]

I was thinking flexplate also. If you want to check to pinpoint the noise like spinning wheels said you don't need a scope. Just get a long screwdriver. Good luck though. Did you have a shop do it? Is there any kind of warranty with it?

[chev-obsession]

did you have your foot in it a lot before it started making these god awfull noises?

[VetteVet]

Rod knocks are usually heard when the engine is under load like when accelerating or climbing a grade. It shouldn't take anywhere near 2500 in gear to hear a rod knock. I would try taking it out on the road and pulling one spark plug at a time and see if the knock goes away. This relieves the combustion pressure on the cylinder and if the knock goes away then you've found the bad cylinder.

[special-K]

I`d still look into the flex-plate/torque convertor area,first.It doesn`t always make the same noise and definately can sound like more than a tap.More times than not it sounds like the bottom end is coming out of it.Drain oil into an absolutely clean container and do an oil analysis.Take a piece of something clean,rigid,and white(like corrugated sign board from Walmart),pour oil a splash of oil on there and let it flow down.look for metal bits.If you can`t see anything,run a rare earth magnet over it or even scrape it across with the tail end dragging.If there are no fragments there is no internal damage.I`d also tear the filter apart and see what`s in there.

[cdowns]

an old harmonic balanced on a worn crank snout can sound and feel like rod knock too //just look at it and see if its wobbeling

[DANTIP]

Is your oil-pressure normal? You also said it only knocks in gear, does that mean it does not knock in Park or Neutral?

[americanmusc1e]

Originally Posted by chev-obsession

did you have your foot in it a lot before it started making these god awfull noises?

yes

[rob32472]

it sounds like you know what it is..... if you have a warranty see what they will do. if not....... when i was younger my dad told me that when it comes to driving my foot would be the bigest money saver in my life... didn't understand until i bought tires, brakes, drive shafts, rear ends, motors and was constantly workin on my truck then it just hit me and now i spend my money on things i want instead of what i have broken. lil off topic but just my two cents.... hope it works out

[americanmusc1e]

well, I must have been having a bad day yesterday. Today the truck is almost normal. Its still making a little noise but its not near as severe as it was yesterday. I'm gonna give the truck a tune-up and see if that helps.

[americanmusc1e]

It did it again today, I finally checked my oil pressure gauge. when its acting fine I have about 30psi at Idle and about 70psi max.
when it starts making noise it drops to 0psi at Idle and around 20psi max.

[70rs/ss]

Low on oil?? And except the oil pressure, I was thinking a ping (detonation) vs knock but a ping wouldn't lower the oil pressure.

[spinning wheels]

Originally Posted by americanmusc1e

It did it again today, I finally checked my oil pressure gauge. when its acting fine I have about 30psi at Idle and about 70psi max.
when it starts making noise it drops to 0psi at Idle and around 20psi max.

Question no. 1: What kind of oil pressure gauge are you using?

Question no. 2: What kind of valve covers are you using? Do they have baffles around the PVC valves? If not, you may be sucking up the oil on the heads thru the PVC valves. This would cause your loud valve train.

Question no. 3: In reference to question no. 2. Are you using a lot of oil?

[americanmusc1e]

Originally Posted by spinning wheels

Question no. 1: What kind of oil pressure gauge are you using?

Question no. 2: What kind of valve covers are you using? Do they have baffles around the PVC valves? If not, you may be sucking up the oil on the heads thru the PVC valves. This would cause your loud valve train.

Question no. 3: In reference to question no. 2. Are you using a lot of oil?

Oil pressure gauge is equs mechanical, using valvoline racing 20w50 non synthetic

stock centerbolt valve covers. PCV hooked up

not using hardly any oil, I have oil in the motor right now

[spinning wheels]

Not sure how good equs gauges are. I have seen them around, but I personally don't know anybody using them.

These are just some suggestions, I'm not an expert on this stuff. I only play an expert on the web
Low oil pressure, usually means a higher than normal bearing clearance, which can cause a low pressure reading.
Or, your oil is not getting to the top of the engine, which would mean your oil pump is either weak or plugged up. Being a new engine, it could have anything from silicone (sp*), to gasket material, or something let loose (failed), on the new engine that has settled into the oil pan and gets sucked into the oil pumps intake.

I could be wrong, but I would check your oil pump. Could be something as simple as the shaft damaged. If that is ok, I might pull the oil pan, I know, its a PIA. This would let you get a good view of the oil pump.

Have you cut open one of your oil filters, to check for metal deposits? If you don't have a filter cutter, check with the engine builder.

Whatever you do, just stay cool, calm, and collected. Keep the young one(s) away, so they won't hear you cusing. Keep the dog(s) away so you won't kick it. Keep the wife or GF away, so well, you know

[special-K]

When did you change the oil?How many times?How long has it been?Have you smelled the oil?I wonder if you have drain back from the carb.Or,a wiped bearing?Once the oil warms up oil pressure is low.The crank could be turned a bit beyond tolerance.Was it ground?Undersized bearings?The oil test I described would help narrow down if it`s improper tolerances.There wouldn`t be any grindings.

[68C15]

I'm thinking a spun main bearing or two.
the pan needs to come off, NOW

[americanmusc1e]

Originally Posted by 68C15

I'm thinking a spun main bearing or two.
the pan needs to come off, NOW

should i pull the pan???????? or just bite the bullet and pull the motor????????????????????

[americanmusc1e]

Originally Posted by special-K

When did you change the oil?How many times?How long has it been?Have you smelled the oil?I wonder if you have drain back from the carb.Or,a wiped bearing?Once the oil warms up oil pressure is low.The crank could be turned a bit beyond tolerance.Was it ground?Undersized bearings?The oil test I described would help narrow down if it`s improper tolerances.There wouldn`t be any grindings.

Oil is changed every 3000 miles. changed oil less than 1500 miles ago.
4 quarts valvoline racing 20w50 1 quart marvel mystery oil

I noticed this after the noise started so I guess its connected. usually my oil pressure runs between 40 and 60psi