New GM L31 crate engine has awful oil pan noise.

[Schurkey]

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.

Additional:

The M77 (Big-block Chevy) pump, the 305S 3/4" pickup tube for 7 1/2--8" deep pans, and the steel-sleeve driveshaft is sold as a package: M-99HV-S

Some trimming of the windage tray is required. The BBC pump has a very different location for the pickup tube, and it has more gears on the rotor for less spark-scatter--smoother operation. About $77 at Summit.

https://www.summitracing.com/parts/mel-m99hvs

I suggest ARP for the oil pump mounting stud.

 

[Pinger]

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?

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Cheers


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Have you tried locating where the noise is from by sounding out the oil pan? I have finger nails - not absurdly long just long enough that they can contact a surface end on - and I'm pretty sure that they would get closer to pinpointing where that noise is coming from.

 

[Fragment]

Have you tried locating where the noise is from by sounding out the oil pan? I have finger nails - not absurdly long just long enough that they can contact a surface end on - and I'm pretty sure that they would get closer to pinpointing where that noise is coming from.

I don’t have finger nails anywhere near like that but I definitely know it’s coming from the sump.


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[Fragment]

Update -

Replaced the Chinese distributor with an AC Delco last night, and while it solved my timing issue, the oil pump noise is still present. So that pretty much confirms it for me that it’s the oil pump. I have a melling m155 on the way and should be here this weekend.

A new development on the GM front however... got an email yesterday from my contact at the GMPP dealer that sold me the engine, and he said he hasn’t heard a 100% answer yet, but thinks GM will likely cover a R&R at my local dealership for a new engine. So it seems to me like they know a little something about these things having issues if they’re willing to cash out that much labor and a new engine. This is all good news I guess... I’m just not convinced the dealership would do the same quality job that I would on putting the thing in.

Do any of y’all have experience with a dealership engine replacement? I’ve never come close to having anyone else do that much work on a vehicle of mine. Much less on a 22 year old vehicle.

Part of me wants to replace the oil pump Saturday myself and see if it fixes it, the other part of me says if GM is offering a new engine, then take it... not knowing if this oil pump has sent metal into the engine.

What would you do?


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[Erik the Awful]

How well do you trust the GM techs? I'd talk with the GMPP dealer and let them know you have a new oil pump on the way, and have the GM dealership try that first. If it fixes it, GM can reimburse you. If not, jump to the engine swap and the oil pump was on your dime.

I wouldn't worry too much about pumping metal through the engine, the very first destination for the oil is the oil filter. Throw a new filter on there and call it good.

 

[Fragment]

How well do you trust the GM techs? I'd talk with the GMPP dealer and let them know you have a new oil pump on the way, and have the GM dealership try that first. If it fixes it, GM can reimburse you. If not, jump to the engine swap and the oil pump was on your dime.

I wouldn't worry too much about pumping metal through the engine, the very first destination for the oil is the oil filter. Throw a new filter on there and call it good.

Not a bad plan.
Good to know the filter is the first in the chain. Didn’t know if it was first or last in the loop. This makes me feel better for sure.

Will cut it open to inspect as well.


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[red98]

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

Turn up the radio LOL

 

[Pinger]

I don’t have finger nails anywhere near like that but I definitely know it’s coming from the sump.


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Where in the sump though?
I'd want to know for sure it was rearwards - not forwards and the cam chain.

 

[Fragment]

Where in the sump though?
I'd want to know for sure it was rearwards - not forwards and the cam chain.

Rearward. Right about above where the indented “X” is in the sump.


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[jaywestfall]

Update -

Replaced the Chinese distributor with an AC Delco last night, and while it solved my timing issue, the oil pump noise is still present. So that pretty much confirms it for me that it’s the oil pump. I have a melling m155 on the way and should be here this weekend.

A new development on the GM front however... got an email yesterday from my contact at the GMPP dealer that sold me the engine, and he said he hasn’t heard a 100% answer yet, but thinks GM will likely cover a R&R at my local dealership for a new engine. So it seems to me like they know a little something about these things having issues if they’re willing to cash out that much labor and a new engine. This is all good news I guess... I’m just not convinced the dealership would do the same quality job that I would on putting the thing in.

Do any of y’all have experience with a dealership engine replacement? I’ve never come close to having anyone else do that much work on a vehicle of mine. Much less on a 22 year old vehicle.

Part of me wants to replace the oil pump Saturday myself and see if it fixes it, the other part of me says if GM is offering a new engine, then take it... not knowing if this oil pump has sent metal into the engine.

What would you do?


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I just bought one of these engines myself. Thanks for the heads up. I have the Melling kit here already because I was going to swap it out on my old engine before it became fatal.