So, I didn't put enough oil in the truck, or so I think. Can't remember, but let's move forward.

Today, I hopped in, drove it for about 4 miles, and it started rapping loud. Woodpecker loud.

So I pull over. I'm low 3 quarts.

I fill with oil, and noise stays about the same, except when I accelerate or keep the pedal in motion. Once I remove forward or reward motion, the rapping starts back up.

I can control the knocking noise with my foot.

Neutral is the loudest.

Pulled the inspection plate, and all the bolts are where they're supposed to be. Sounds like a cracked flexplate as well, but I have one of these SFI units in there, and I don't beat on the truck.

I'm thinking I ran the truck with 3 quarts low for several hundred miles. I cannot be sure I did this, but this is what I'm thinking.

Ever had a ROD knock ?

Could you control it with fuel ?

Curious to see what other's have experienced.

Thanks.

 

It could also be the thrust bearing, check it by prying the harmonic balancer back and forth (front to rear) there should be no movement.

 

I don't think 3 qts out of 3 gallons of oil would cause a rod knock. I assume you had good oil pressure throughout. Maybe a loose main bearing would cause oil loss. The flex plate would probably make this noise.

 

Quite often with a rod knock the knock will go away with the motor under load...so slowly adding throttle. Then when you take your foot off and the motor has no load the knock comes back.

That really sucks T-man....I hope it's something else like a bent push rod or something.

 

Does the rod knock go away when you crack an injector line? If so, you might have a bad cylinder.

 

I am not very proud of it, but I have ran my truck over a gallon low on oil more than once, and it didn't seem to mind.

Back in the day when we were pulling we went to 3 pulls in one weekend. Well our piston rings were tired and apparently she was blowing quarts of oil out the breather tubes during a pass. When we got to the last pull we checked the oil and there was none on the stick and it took 1.5 gallons to fill it back up. It survived turning 5K on half the oil. We did check the oil a lot more after that and rebuilt the engine that winter. Went to Total Seal rings and that made a huge difference. Also put a catch can on there and monitored the oil loss during a run.

I really don't think 3 qts low would be enough to starve the oil pump.

 

didnt try it, yet

Got a specific process?

 

yesterday, i dropped the oil into a brand new white bucket. Zero metal in the bottom.

Never lost oil pressure. Started it up, and went right to middle of the gauge, and stayed there, although our 30 year old gauge im sure isnt terribly accurate.

Noise still there. Add pedal to aboit 1100, 1200 rpm, and noise is gone. Remove foot from pedal, noise back

 

sending the oil sample out to blackstone labs

 

Cut open your filter. Hopefully you haven't been using Fram.

 

Classic signs/sounds of a cracked flexplate.

I've ran mine 9 quarts low, yes i'm lazy. Still chugging along.

Go back to the inspection cover, try prying the flexplate teeth back and forth with a screwdriver, comparing to the front dampner.

You should find a small amount of lost motion. There shoud be zero, obviously.

Any engine, any make, i've ever worked on with bad bearings....the engine oil on the dipstick looked like metal flake paint to as bad as mercury.

You could calm your fears, by cutting open the oil fiter, that wil tell the tale.

When the flexplates crack, sounds like the engine is going to come apart, until you put a (trans) load on it, that keeps the crack in the plate closed up.

Revving up a rod knock would just get louder, especially a diesel, the piston woud be smacking the cylinder head with the added clearance of the worn rod.

Hope that helps

-Mike

( I think i'm going to go check my oil now)

 

No. Just start at number one and work towards number 6.

Any updates?

 

So, Thank you all for chiming in. Most appreciated.

I finally was able to drain the oil. NOTHING in it other than relatively new oil.

I cut apart the filter and found a brand new filter with nothing in it that I just ruined.

I put the fresh oil in, and same thing. Noise at idle, no noise at increased RPM.

So, I called a buddy of mine who's son works on nothing but heavy machinery with either CAT, CUMMINS or other big names, and he wants me to eliminate the bad engine theory here completely. I have to go out and purchase an oil pressure gauge (mechanical), and screw it in. Test the oil pressure at idle and at higher RPM's. I'll then compare to OEM, and not use the idiot gauge on the dash to make a final determination.
So if the oil pressure is not good, there are two possibilities. Oil pressure relief valve gone bad, or the oil pump gone bad. Once I have a pressure to figure out which path to go, I will

This video will explain where the oil pressure relief valve is located, as with poor oil pressure, this is the first, cheapest and easiest fix, so we do that first.

IF the oil pressure is good / normal, then the SFI super duper scooper pooper flexplate I installed several years ago, must have failed, and time to go through that again.

Keep you posted.

 

Not a bad idea to confirm the oil pressure with a mechanical gauge, but I kinda doubt that's the problem. That oil looks super clean.

Something easy to check would be the bolts on the harmonic dampener. Maybe they came loose? I imagine it would make a similar rachet if they did. They came loose on the puller one time, even with a dowel pinned Fluidamper and red loctite. Never really noticed the noise, but with a hood stack, solid hub DD clutch, gutted cab and sheet metal dash you couldn't hear something was wrong until it was catastrophic. It pretty much always sounded like it was going to blow. I don't even remember how I caught it, must have been checking the valve or something. I double checked them a lot after that.

 

In my life and you might not get metal if a bearing/journal is bad. Take a screw driver(Stethoscope-Sonarscope) or a noise scope and spot where the noise is coming from. The bearing where the wrist pins are can get worn on the piston and the rod so you can tell if it's the engine and the location. Also take the serpentine belt off and eliminate all of that as well.

Could be a bad tappet, valve clearance.. could be anything really.. I think the first step is isolating the location/area of the problem.