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Discussion Starter #1
Hoping guys can shed some light on this. My newish Cummins built motor has had multiple irregular noises since getting it back from the shop and I've slowly gotten rid of them except for the last one which could be described as a lifter tapping in an old small block, the noise im chasing is rpm dependent and changes consistently with the rpm, it is a one to one noise. One rotation of the motor equals one tick. The noise is a clack or a smack like you'd hear if pulling apart two steel items that were stuck together hydrodynamical and starts 5 seconds after start up as the oil pressure passes 30 psi or so. I have tried many different oils and tried adding zinc. Power driven diesels oil makes the noise the loudest, it makes the noise more audible the same way adding zinc does. Lubrication engineers 8400 oil made the noise the quietest. Im not interested bashing PDD, theres nothing wrong with their product, its been tested. Oil samples all tested good with no abnormal amounts of metals. I replaced the cam gear for another reason, cp3 and its gear neither of which effected this noise. The entire fuel system has been checked thoroughly and eliminated as the source. I have the engine torn down for a second time, cam/lifters out, valve train torn apart, im micing parts and everything so far looks good. The plunger for the oil pressure regulator has a wear pattern on one side. Does this plunger move consistently with rpm? I can not find a specific operation description of the pressure regulator, but I understand how its supposed to work. Is it possible that with every rotation of the pump it forces the regulator open to bypass pressure? Pressure is 55-60 cold idle, 50psi hot idle, so im not concerned about pressure but I do have to find this noise. As you know once a noise gets stuck in your head its all you hear until fixed. I tow heavy daily and cover around 100 miles daily, I do not want something to fail in the middle of the country. The oil pan is coming off and the transmission is being pulled to get to the rear cam bushing and to check all associated hardware bolted to the crank. Thanks.
 

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The bypass plunger only opens with oil pressure exceeds the spring pressure holding it closed, I doubt its what is causing your noise. If its stuck open your low/idle rpm oil pressure will suffer. If its stuck closed oil pressure spikes with cold oil high rpm and it can blow out seals.

#1 thing you need to do right now is get a real oil pressure gauge hooked up to it and see what your real pressure is. The gauge on the dash is not a real pressure gauge.
 

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Run an oil sample test at an oil analysis lab. Will tell you if there are excessive wear metals and likely sources.
 

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Discussion Starter #5
I will get a mechanical gauge ASAP. The plunger has obvious wear signs as if it’s moved in it’s bore a lot. I ordered a new one with a new oil pump & some other bits. I am no oil pressure expert, I have done quite a bit of reading (a lot here) & this is the first I’ve heard of 50 being excessive. Fsm calls for 30psi for 30 seconds at operating rpm. No spec for max psi. Have you read 50psi max somewhere or is this common knowledge? Oil samples all test good with no excessive contaminants.
 

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Because you wrote 50 psi at warm engine and idle speed. We're waiting for your oil pressure gauge. If it really says 50 psi at warm engine idle I'd say that's too much. Maybe one or more oil channels are blocked. This creates too high back pressure.
Minimum pressure in Idle HOT ENGINE would be 10 psi according to the manual. Usually it is 20-25 psi. I'm reading 22 psi. At 2500rpm minimum 30psi.Usually 50-65 psi. My reading is 65 psi. At top rpm, it goes up until the bypass opens. 75 psi + -. You say your noise depends on engine speed. One revolution equals one ping. Then please try to use a pressure gauge for oil pressure measurement which has NO glycerine filling. These are mostly the cheap ones. The advantage: the pointer is not damped. So you can compare the ping noise with the display if the pressure rises/falls shortly. With a glycerine dampened gauge, this probably very short deflection would be damped away.
This is my guess.
I am really interested if you find the problem and a solution. Because I still have this noise.
I am aware that these engines always make some unusual noises. Sometimes more, sometimes less.
If I may quote you: As you know once a noise gets stuck in your head its all you hear until fixed.
 

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You've probably already checked everything outside the engine?! Screws torque converter, dipstick AT to downpipe, water pump, #4 Fuel Line. Also check the screw lock plates for the rear exhaust manifold screws. Knock there with a screwdriver. They make a high metallic noise. It's unlikely that they will vibrate and sound at every turn, but you never know.
 

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Discussion Starter #8
What are you calling “screw lock plates for rear exhaust manifold bolts”? I just replaced gaskets to make sure it wasn’t an exhaust leak & saw nothing as described.

Truck is a manual which is currently the floor, pans off, flywheel is off-nothing out of place or rubbing, cam bushings just got replaced, still waiting for more parts.

Royal: the dash reads 45-50 hot idle & climbs to 55ish with rpm. I have found a gauge so when I get it back together I’ll see what the system is running at. The biggest issue I’ve been pondering for two days is how the ensure there are no blocked oil passage. I have watched the valve train while the engine is running and all the rockers receive excellent oil, the cam is pristine, the tappets are pristine-no pitting & are within spec. I’m wondering if the relief plunger is opening every time some portion of the rotating assembly passes it’s oil port causing back pressure to increase forcing the plunger open.
 

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The dash gauge is essentially worthless information. Its operated on a low psi pressure switch, the only thing is is telling you is you atleast 8-10psi I dont remember exactly what pressure its rated for. The ECM just makes up a reading based on rpm and engine temp from there.

For your pressure relief to make that kind of noise you would have to have wild fluctuations in oil pressure, even with veins broken off of the oil pump I dont think its possible. All of the oil system is pressurized simultaneously regardless of your rotating assembly orientation. The oil pressure relief valve is only really used when the oil is cold and rpm is high.

I know its harped on here alot, but if you went with rebuilt injectors it can cause you alot of headache.

also did you replace the rocker arms when you built the motor? When I rebuilt mine I missed the #5 exhaust adjustment and was making a noise every rotation like you described because it was way too loose.
 

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Ah ok manual transmission. I couldn't find it in your signature :wink2:
You could also suck the oil out of the rocker arms so that they are dry on top. Start the engine and see when which rocker arm gets oil. Should start from #1 to the back #6. This is at the end of the oil channel in the block. I don't know if you can see any time resolution there. But if one cylinder or rocker arm gets oil much later than the others you could continue to search there?!
Do you have a video with sound of the ping, klong noise.
 

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Discussion Starter #12
Squeak: when I was referring to the rotating assembly I was thinking out loud that if there was something that in one specific spot of let’s say the cam, caused an momentary blockage of one of its bushings oil passages it would create a sudden spike in pressure before the pressure was relieved either at the relief valve or the flow was increased at another oiling port. I’ve got this thing torn down so far with no obvious signs, gotta think outside the box. I bought new injectors from exergy, motor lost #1 cylinder shortly after install. Injectors were sent back to be tested & cleaned before installing in new motor. Injectors were removed,tested, cleaned again before move to Tennessee. New Bosch connector tubes too. New cp3. Cummins built the motor in 2015, shop installed it in 2018 & swapped in Hamilton cam. Rockers were not set right, 6 plastic retainers broke. All rockers were replaced by me with new 6.7 units 150 miles after initial start up. Hamilton 103 springs & hd pushrods installed at 8,000 miles with cp3, external filtration & a new front end. Cp3 & external filtration seemingly made noise louder, I assumed from load on gear train, but now....? Cam gear was warped by shop when removing it from oe cam & installed on new cam causing noises as it walked around on cam snout. I just replaced cam gear, cp3 gear, forward cam bushing & some other bits two weeks ago. Noise seemed louder after this. Seems to come from right side of cylinder head, right at #1 cylinder. Which is also right above the heat exchanger. Should be running Tuesday & I did find a gauge in with my compressor fittings which reads the same as all three of my other compressor gauges so hopefully it’s accurate. It’s not filled with oil.

Royal: I do have a video of the noise but it’s hard to separate from all the other noises. The video needs to be bluetoothed to a stereo that has an equalizer to muffle bass & exaggerate treble. The motor is torn down so far I will be able to see which rocker produces oil first or if they produce oil out of order. So, if the rockers are 1-12 does that mean mains are in the same order? As well as cam bushings. Oil flows front to back or does it spiral through the motor. I wish there was an easy way to fire this thing without an oil pan on it. Wouldnt be too hard to make a pickup tube & run it into a bucket of oil I suppose. Just messy. My motor does not have the tie-bars on the mani bolts.

If the noise isn’t fixed after this round of repairs watch the local Fox News station in Tennessee on Friday to see a video of a white dodge engulfed in flames hurdling off the bridge into the Mississippi!
 

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Lost an injector on #1, noise is around #1 and rpm related.
Does it reduce as the engine warms up?
Sounds more like the piston has been hot and maybe shrunk a little and what you are hearing is a little piston slap.
If you can get hold of a borescope it may pay to check that piston top and bore.
What work was done on it before this noise was noticed?
 

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Discussion Starter #15
I never thought about that. It’s gotta be a ty coincidence unless there’s something stupid I’ve overlooked. The noise begins 4-5 seconds after start up hot or cold when the oil pressure builds & stays constant all day. Like clock work-engine fires & a few seconds later the noise builds. Possibly slightly louder after a hard pull yankin the 9000 pound trailer through the little canyon by my house...MAYBE. All the cylinders got borescoped when I pulled the injectors before the move to Tennessee. The pistons were perfect as was the cross hatch. No signs of detonation or piston slap. Damn it, I should have scoped them when I had the valve train out, I literally just put it back together & set the lash.

As far as cp3 timing goes, I tried it a dozens times with the old cp3, at least a dozen times with the new cp3, replaced the cp3 gear & cam gear a few weeks ago-noise didn’t change. It sounds EXACTLY like a few of the cp3 timing videos on YouTube. I was positive that was what I was hearing when I found those videos on YouTube a year ago but unfortunately it wasn’t the cause. I’m praying it’s the oil pump gears since the noise I have sounds so much like the cp3 timing videos which is simply gear lash.

The one thing I forget to mention here is that the forward #3 exhaust valve stem is snug in its guide. I checked them all for excessive play when I did the valve springs & that one valve was slightly harder to move up & down in it’s guide. I borescoped the exhaust ports & all the seats seem to be in good condition or at least they all looked identical through the scope.
 

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Discussion Starter #16
Trucks running. Noise remains but there was a 45 second period of no noise this afternoon. Oil pressure gauge reads 70psi at idle, find that hard to believe. Ordered another one. Planning on running a bunch of marvel through it right before this oil change.
 

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Using real gauge??
Normal operating temp oil pressure should be 70 psi max
When oil pressure exceeds 517 kPa (75 PSI), the oil pressure relief valve hopefully opens exposing the dump port, which routes excess oil back to the oil pump.
The engine could have high oil pressure at normal operating temperature if the lubricating oil pressure regulator valve sticks in the closed position.
 

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Discussion Starter #18
Yes, with a real, non oil filled mechanical pressure gauge. When I had the exchanger off the engine I cycled the regulator valve manually & it seemed to function properly/move freely but I know there’s no replacing 70+ psi pushing on it. Closed would be in the seated position, open meaning the spring is compressed, correct? I’m kicking myself for not replacing it when I had it apart. It’s so damn cheap. Are you guys reusing the heat exchanger gaskets.
 

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Proper spring test is to measure spring height 1.62 inch with load of 28.4 lbs, and free length 2.6 inches
Replace the spring if out of limits.

For plunger inspect the plunger and plunger bore for cracks and excessive wear.
Polished surfaces are acceptable. Verify that the plunger moves freely in the bore.

In the big picture gaskets even cooler are cheap, motor is not
If reusing exchanger/cooler, should pressure test to verfiy no issues
Clean the sealing surfaces. Apply 483 kPa (70 psi) air pressure to the element
to check for leaks. If the element leaks, replace the element.
Make sure gasket is correct !!
 

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Discussion Starter #20
Motor definitely not cheap! 20k now. I replaced the plunger/spring with oem parts. The old plunger had to have moved as there were obvious signs of vertical wear marks in two places. The bore looked good, plunger moved freely. The cooler was reused since it only has 15k or so on it. I did a rudimentary pressure test as well as thoroughly clean it-all seemed good. Really pissed at myself for not replacing regulator. I’ll order one Monday.
 
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