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Hollow thumping noise when cranking

1122 Views 39 Replies 5 Participants Last post by  WaltKowalski
After installing new heads in my early '04 6.0, I started cranking to build oil pressure. 10-15 seconds with 45 seconds in between.
I have a hollow, thumping sound on the driver's side, at the same point in each cycle.
I pulled the valve cover and checked my rockers, push rods, and bridges. All seems to be in order.
When it's cranking, I can hear what seems to be a sucking sound from the intake valve, and the thumping from the exhaust valve, in the #2 cylinder.
No previous problems with the lifters that I am aware of. Ran great before the head gasket failure.
I'm at a loss, and obviously need some experienced guidance.
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Thumping noise audible from the exhaust is usually from a valve being open/stuck at the wrong time. Thumping out the intake is usually from exhaust valve not opening, out the exhaust can indicate intake valve not opening or barely opening . I would think you would have very low if not any compression on the offending cylinder though. All rockers move the same on all cylinders?? Have you measured the rocker travel with a dial indicator to be sure?

Is it possible you didn’t have a pushrod seated correctly when you torqued the rockers down?
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I was concerned with a lifter that "bled down".
That is very possible, and he should be able to see this turning the motor over
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I drained and refilled the oil to check for water and fuel, since I had everything apart. No water, no fuel.
The pushrods seemed to be in good condition and position when I double checked before torquing everything down.
What would I be seeing if the lifter bled down, while cranking?
How do I post a video here?
I keep getting a message saying that the file is not supported.
You’ll have to host it through YouTube or something similar.
Have you pulled the other side valve cover?
It sounds like you have more or less even compression by the sound of the load on the starter. Do you have FICM sync/sync, FICM injector power, proper fuel pressure and ICP pressure?
50 psi is on the low side. I would see if you can check your ICP pressure but you’ll need a scan tool or FORscan for your phone.

Believe it or not I’ve actually had the LPOP make that type of noise before in a crank no start.
I have a Bluetooth adapter on it's way, so I can use forscan.
I'm not sure if it's actually a crank/no start, because I pulled the ficm relay until I know it has enough pressure. I installed a higher output alternator and don't want to fry the ficm with the cranking.
What was the problem with your LPOP when it made the same sound?
It’s not actually a problem. It’s the noise from the hydraulics I believe. I’m not sure if the pump is in pressure relief or not, but as soon as the engine starts it doesn’t make the noise any more. You can probably hear it because you aren’t fighting noise from combustion with it’s just cranking.
In a conversation with @Hartwig a while back, he noted a sound that was present with a "dry" first start engine -- but was not like this thumping
It’s tough to distinguish noises over a video. I said it sounds similar to the noise, I’m not sure if it’s the same exact noise. But I have heard gerotor pumps make this type of noise before. It is certainly not common, though. To me it sounds like he has more or less even compression based on starter load; the starter does hang up slightly in conjunction with the thump I notice, though. it sounds like the batteries may be getting a little tired, I am also curious about his cranking RPM via datastream (plus other pids). Regardless of the noise it should still fire up on 7 cylinders if it’s a valve issue. That’s why I suggested he put it all together and try to start it.
Hope you are right!
I hope so too but I’ve been wrong before!!
Unplug the vacuum pump, don't need it right now anyways
Put the relay in and fire it up
surely already cranked enough to prime the oil
Yea, this. Try to start it and see what happens
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I don’t get why people ask for help but never post updates for said help 🤷🏻‍♂️
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