Needing some help here. I had my motor gone through with new bearings and rings a few months back with 112K on it. I did a mild cam, new valve springs and rockers while I was at it plus headers and ORY. After some testing at WOT on the original transmission it started slipping real bad. I pulled the trans and had it rebuilt locally. They installed a new TC at the same time (put it on the trans that is) and then I reinstalled the trans/TC, filled it up and went driving. I have about 500 miles on it since then and a few days ago I did a WOT run from a dig up to the 2-3 shift at about 6000 to log data for a tune. As I slowed down from high speed it immediately started a loud chirping that sounds like it's happening at about the same frequency as the motor rpms. I made it home while being easy on it which was about 4 miles or so. It seemed to chirp louder when accelerating and was a lot quieter when decelerating. I put it in the air yesterday and didn't find anything out of the ordinary. Checked the flexplate best I could for cracks and checked the TC mounting bolts were tight. In the attached video you can clearly hear it. Motor has oil, trans has fluid on the dipstick when cold and idling. I left my driveway the next day and about 100' later it killed the motor at low speed low throttle. I was able to restart it with even louder chirping and backed up into my garage. Any thoughts on this? At first I assumed TC since its making the sound in neutral (rules out the trans). Now I'm wondering if one of the bearings is trashed. This is an LT1 motor but there's very little traffic in that forum and this would apply to all motor generations. Thanks.

 

Ouch.

Spun bearing or broken crank.

 

Hearing that, have you tried running the engine without a belt?

My last spun bearing was a gen I sbc, but it sounded like a ball peen hammer on the side of the block.

 

I'm going to run it without the belt tonight or in the morning for the next step. Hopefully not a broken crank considering the engine builder showed me that it had a forged crank in it when he tore it down. Regardless if its internal I'm incredibly pissed this thing only lasted 500 miles. It was so much fun pulling the motor and trans the first time...

 

I highly doubt that is broken crank. What is your oil pressure at(and is the gauges you're using accurate?)
If it is a spun bearing, I wouldn't run it much to further the damage.

 

Cut your oil filter open and inspect. You will know pretty damn quick if it's a bearing.

 

Well I just ran it without the belt and no change. So that eliminates alternator, P/S pump, A/C compressor, and idler pulley. Water pump is shaft driven off the timing gear. It's definitely loud and seems like its coming from the motor. I'll drain oil and open up the filter next.

Oil pressure is maybe 40 on a cold start just now. That's assuming the dash gauge is accurate which is probably the original oil pressure sending unit from 1995.

 

I would quit running it if I were you. You're increasing the damage

 

No more running it. Drained oil today and it�s glittery. Small bits of metal floating in the sample I poured out of the filter too. I don�t think I even need to cut open the filter at this point. I guess now we�ll see what the machine shop will actually do as far as warranty for their work. This was only about 5 months and 500-600 miles after the rebuild reusing the rotating assembly. Never went over 6000 rpm and had enough oil in the pan. In fact I bet it only saw high rpms on maybe 8 runs while logging data for the tune. I�m hoping they�ll disassemble the long block, clean everything and repair any damage (or I find some cheap stock LT1 parts for sale).

 

Oil starved bearings most likely culprit.

 

Time to go LS. Don’t look back.

 

Oh I know. I've had multiple LS cars over the years. This was a first car project intended to be for my 13 yr old. Bought this one for cheap since it wasn't running. After new bearings and rings in the shortblock and rebuilding the trans (which I wasn't planning on), had this crap happen. I'm tempted to get it repaired and just offload it at this point. Pulling motor/trans twice within a few months is not fun.

 

More than likely nothing.

 

What ended up being the problem. Mine is making a similar noise.

 

OP hasn't been here since 4/15/22