VY V6 Ecotec rattle/tapping

[jaseWH2]

Hi.

Just wondering if anyone can help with thoughts on what may be causing this rattle or tapping in a VY V6 Ecotec engine. A couple of months ago I rebuilt this engine and it was running nice then, but it has developed this tapping sound that shows up when first starting the engine, then slightly at idle, goes away once you rev it up a bit then if you close the throttle and it drops past what's probably 1000 revs it makes more of a rattle sound and then stops again.
I am wondering if it's the balance shaft bearings, as I didn't change them in the build, or something to do with the timing chain, but I put a new timing kit on, so I am struggling to think it would be that. I have read a few posts on the balancer as well, but I don't think this sounds like any that I have heard online.
I also removed the main belt just in case it was any of the accessories, but it wasn't any of them.
I am going to look at this in the morning, but thought I would ask the question now in case anyone had any ideas tonight.

Thanks,

Jason.

https://vimeo.com/265731603

[whitels1ss]

Very hard to tell exactly from a youtube clip but it sounds like it might be lifters to me?????

[jaseWH2]

I always think that as I watch other people's video! Nothing better than seeing and listening to something in real life. A microphone on a mobile device just doesn't cut it.
Anyway, thanks for your suggestion. I am really hoping it's something in the top end rather than something more sinister down below cause I really don't want to pull this engine out again!
At idle it's a fairly consistent metallic tapping noise that leads me to think it's a lifter/rod/rocker/valve, but the rattle on the way back to idle makes me wonder if it's something else.

[whitels1ss]

Sorry I can't be more help mate,
all the best with it! :cheers:

[jaseWH2]

All good. It's hard when you're not in front of a vehicle to diagnose! I am starting to wonder if it may be low oil pressure from the original oil pump that's still in the engine. I have pulled the lifters out and had a look but they really don't have a lot to them internally apart from a valve disk and the top plunger, so I doubt after cleaning them at rebuild that they are the issue. Your comment about lifters though made me think that the drivers side lifter gallery is feed pretty much last in line on these engines I think.
Now to put all the top end back together, find my oil pressure gauge sender and test that theory, then pull the timing cover off and check out the pump... A fun afternoon ahead I think!

[jaseWH2]

Big day with no positive outcome :( I checked lifters, oil pressure was at around 65 PSI at idle, timing chain was tight, I removed the gear for the balance shaft and checked the harmonic balancer.
It seems to me most likely that the gasket on the rear engine cover may be somehow blocking the oil feed to the lifter galleries, but without pulling the engine out it's hard to say. There is oil that pools on top of the rockers, so there is some oil getting through, but I am wondering if there just isn't enough pressure getting through to the lifters.
At the moment I think I am going to leave it as is, but unfortunately I think the clacking noise at idle may have gotten louder after everything I have done today! It is hopefully just cause the oil needs to get back up the top again...

[Jason01]

What about trying a mechanics' stethoscope or at very least a screwdriver handle up to your ear, either might help you pinpoint where in the engine it's coming from. It's really hard to tell from the video but it does sound a bit more terminal than a lifter to me, hopefully it's not, good luck.

[jaseWH2]

I have pretty much given up for now and put everything back together under the assumption it's not enough pressure to the lifters to keep them pumped up. After it's warmed up then about the only noise that is still there is the small rattle on it's way to idle. I am in half a mind that maybe my main and rod bearings were possibly towards the outer limits of their clearance when I assembled the engine and too much oil is flowing from them to make it to the back of the engine then up to the top.
I am thinking of looking around for higher volume/pressure oil pumps and try this first, then I may be looking at pulling the engine out again another weekend to check the rear cover seal and maybe check the bearings again.
Should have just gone with the wrecker engine in... I thought the rebuild option would have ended up being more reliable in the long run!