New GM L31 crate engine has awful oil pan noise.

Not sure if this is related to my other thread about the distributor problem or not, but highly doubting it because it makes the same noise when priming with a priming tool.

Can anyone help me identify this noise? It sounds like the oil pump chattering against the oil pan to me. Surely GM crates have stuff like this quality checked?



https://youtube.com/shorts/eHMqU1FaUJ0?feature=share

Man that's wierd ... do you have pressure build up?

Indeed that is strange. Pull the distributer and look at the teeth, or as a last resort the oil pan.

Is this the newest production of the L31 just introduced last year?

The new Gen1e part number 1269163?

The pressure is great, no problems there. What would I be looking for on the teeth? It’s a new distributor so they are not worn.

It is part number 12691673 so maybe? This is the first I’m hearing about gen 1e.

Get this... I emailed the GM Performance Parts dealer that sold it to me inquiring about the noise and sending them the video. His entire response reads

“Yeah they have noisy oil pumps.”


Does anyone on here think this sounds like a normal “noisy oil pump”?

If it's noisy when priming, I don't know what else it could be except an oil pump issue.

Even if the pickup was too close to the pan, it shouldn't move during priming.

I think you're going to have to pull the pan to inspect. MAYBE you could poke a videoscope up the drain plug hole.

Seems a bit loud to me. Maybe just add a louder exhaust like dumping headers in the wheel well. That'll get rid of the noise

So get this... in an effort to help troubleshoot I thought I’d slow the video down to try and pinpoint the sound.

In doing so, I recognized a pattern in the rattle. With (F)s for fast tap and (S)s for slow, the pattern is F.F.F.F.F.F.F.F.S.S.S which is eleven total taps. But maybe there is fourteen taps with “double” taps on the S? Fourteen is the number of teeth on the distributor gear is it not?

So now I’m wondering if this is related to the distributor problem I’m having as well with what I suspect to be a junk Chinese part.

This evening I’ll be replacing the junk Chinese distributor with an AC Delco, so we will see if that makes a difference.

I have an oil pump and gasket set on order for this weekend if not... but I sure am hoping to avoid tearing off the pan of this new engine.

I may be losing my mind... or just being overly optimistic. What do you guys hear?



Cheers


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There is a reason I put Melling M77 oil pumps with the included high pressure spring on an oil pump stud using the matching 3/4" pickup and a melling steel sleeved oil pump driveshaft in all my small blocks. The newer M155 pumps are hit and miss.

Fragment said:

The pressure is great, no problems there. What would I be looking for on the teeth? It’s a new distributor so they are not worn.

It is part number 12691673 so maybe? This is the first I’m hearing about gen 1e.

Click to expand...

Sorry, I left out a digit.

The new L31 "Gen 1e" 12691673 is the new production engine that is allegedly CNC milled and built to closer tolerances. The original L31 was selling for around $2000 when they stopped production a year or so ago, there was almost a year pause, and the Gen 1e was offered. So for another $1000 I am HOPING they are an even better made motor--not that the original L31 was bad to begin with.......

Edited to add: The LD version is now 4 bolt main, which may explain part of the higher cost.