Vortec 5.3 Swap - making a "thumpy ticky" noise @ back in Intake Manifold (1 Viewer)

[dudenhoeffer]

I posted this video on a couple Vortec forums, noone so far seems to know what the cause of this noise is... I posted this video:


So I'm going to throw it up here and see if all you "toyota guys" can shed some light on the situation. Happens when warm. Takes a minute to start again when re-starting the engine already warm. Noise pattern stays constant even when reving. Engine runs great.

Sound is kinda "hollow" or "thumpish". Not metallic. I've crawled all over the engine and listened but for the life of me I cannot figure what is causing it. Def on the top side at back on intake, not the dust plate on the 4l60e or flywheel or starter. Any ideas?

Any thoughts are much appreciated1

 

[cruisermatt]

Did you remove the intake and throttle body and shake it?

 

[TonyP]

If you put your hand on the rear of the intake can you feel it thumping?
If you have a long socket extension you can use it as a 'stethoscope' up to your rear to pinpoint the area whether it's intake, valvetrain, or drivetrain.

 

[EasternYeti]

+1 on the sethascope suggestion

I’m one of the blessed individuals here that has managed to completely blow the back off my intake...supposedly a bad backfire.

So this being said I can tell you it’s easily removed over the course of an hour or so. I’d pull it right off and look inside, listening is only getting you so far, open it up. Maybe a piece of plastic is cracked and thus hanging off in there?? God knows. Wasn’t impressed with mine

If you do remove it, take your time re-torquing the bolts because they are known to snap

The intake is also cheap to replace via eBay with a new unit - PM me if you want a link to the seller I used

 

[dudenhoeffer]

Thanks for ideas guys - here's a couple updates:

I changed the oil and included a quart of Lucas Conditioner. No change.
(This totally fixed the noisy lifters on my 5.7 in my van. No such luck here)

Put some SeaFoam in the fuel tank about 100 miles ago. No change.

Did you remove the intake and throttle body and shake it?

I removed the intake today. Shook it furiously. No rattles, didn't spot any cracks, everything seemed fine... Gaskets were clean and tight. I replaced with Fel Pro when I reinstalled... No change.

If you put your hand on the rear of the intake can you feel it thumping?

I cannot feel the thumping. Can't find the source with a stethoscope either.

This is the LM7 motor. So, no AFM to worry about.

This noise takes 3-5 minutes to begin REGARDLESS of a cold start or warm engine. It happens at 130º or 200º - temp seems to have no direct effect... like things expanding as the temp rises.

I can turn off the engine and restart it 3 seconds later... no thumping noise.... it returns eventually and always "ramps up" from a softer volume / inconsistent pattern until it eventually hits a constant pace (like the video) and is much louder.

I added a manual oil pressure gauge too. Getting 40 at start 34-35 when warm at idle. Up to 60psi when revving. Stays consistent when sound starts.

Got a stethoscope and probed all over. I couldn't find the source of the sound anywhere. Couldn't even hear it at all when probing the Intake!? So it must be traveling from somewhere else?

The 3-5 min delayed start of the sound with every restart makes me think its not mechanical valves / lifters... seems they'd start right back to making the noise immediately. Wonder if an injector might be acting up?

@MANUCHAO - Tagging you on this thread since you've been lending your expertise too.

I'm a bit of a neophyte here... More ideas?

Thanks!
Don