LS Oil Pump Mods M-295 oil pump Porting/Shimming Complete DIY 

jeffdubray@ Gmail.com 👍

Blue printing or smoothing oil flow and shimming .100” will increase the bypass pressure. I wouldn’t go past .100” shim, we haven’t tested above .100” and don’t want you to have any issues. Thank you for the feedback I appreciate it! JD

@@HeadFlowInc thanks I appreciate it I was referring to mainly the smoothing out the sharp edges, rounding out the Sharp 90 degree exit point and removing the ramps down to the floor for a smooth transition. I'm not sure if I'm going to do anything with the spring or not. but those ramps, edges and sharp turns definitely cause turbulence in there and affect the flow of oil. but I'll probably just leave the spring alone unless if you think that I need to because of removing material and reducing turbulence?

Honestly, if you plan to rev the engine above 5300 rpms I recommend shimming the bypass spring on a stock pump. The stock pump begins bypassing oil internally between 5000-5300 rpms which negatively affects the oil supply when turning higher rpms. Most cammed 5.3’s turn 6000-6500+ rpms. My 4.8 turns 7000+ rpms and I have no concerns. JD

is this recommended on stock 6.0 LQ9

@@sailshane . Yes this would be equally applicable and recommended on-in my opinion:and engine that is experiencing low oil pressure symptoms or before they occur, if the oil ports are shaped and curved like this video covers. This will probably will usually always be the case on any LS Engine, but im just guessing in that. I've rebuilt one engine. Twice. All because of AFM lifter failure and the second time around i just went ahead and did a full AFM delete on my 2011 5.3L Gen 4. Right now I'm probably about 25,000 miles since that rebuild, and the engine's running great. I never had low oil pressure issues but I went ahead and did what he recommended in this video anyways since I was already that far down into the engine. I also had to rebuild my transmission because it failed about 7,000 miles ago, and since I put on a new torque converter and did the full rebuild on that transmission with new clutches and frictions, I now average 19-21 miles a gallon, whereas before I rebuilt the transmission hours averaging at best 15. So my engine, always firing 8 cylinders by not having active fuel management is running great and all those little things like What He suggests in this video but most importantly frequent oil changes I think contribute to its good health and performance. Good luck!

Jessica Watson- English Thank you so much for the kind words! Go slow and build up your tools, having the right burr makes a big difference. It’s great to hear you’re porting! Thanks again keep up the good work! JD

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Andy C You can feel the sharp edges on those turns inside the outlet to the engine. Thanks for the feedback I appreciate it! Thanks for watching! JD

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Bama Dave Yeah, I’ve had to do it to the dampener bolt in the crankshaft, they can be stubborn. Thanks for watching and the feedback I appreciate it! JD

Kenneth Albert Be very cautious using heat as you stated the last think you want to do it warp the housing where the gears ride. Also, iirc the bypass plug is a Metric Allen head, make sure you have the right size. I’ve had these same issues with the Allen trying to slip and holding the pump body it’s definitely frustrating. Using heat seems to have worked so it’s a great option used sparingly. Thanks for watching and the feedback I appreciate it! JD

Bama Dave I’ve done it both ways, on this build I used the feeler gauges to center the driven gear. I haven’t seen any need to leave the cover off or remove it for installation. I don’t knock anyone for doing it, I just don’t use that technique. I may make a video showing both ways to validate any advantage between the methods. Thanks for watching and the feedback I appreciate it! JD

Normally with factory bearing clearance I see 70+ psi oil pressure at WOT M-295 pump with a .100” shim stock bypass spring.

The cover plate is centered by the countersunk bolts there’s no way to adjust. JD

I normally offer the porting/shimming service on any LS pump $75.00 The M-295 is the Stock replacement pump by Melling. A better out of the box pumps are the 12095 and 12096. I do not recommend the 10355 pumps , in a non-DOD application unless you will have an oil pan/system capacity of 8-10+ quarts due to very high pressure/volume; 80+ psi. JD jeffdubray@gmail.com

Arturo Zarate Fully warm, idling @850 rpms, 5w-30 oil it’s at 48-50# Cold start it’s around 60#; we’ve really had good results especially under WOT. JD

Oh my, you only shim the spring .075”-.100” it’s nowhere near coil bind. Using my HF digital calipers the piston/shuttle measures.5710”

@@HeadFlowInc Thanks for sharing. Relief piston has area of .256 sq in. Spring rate of 17.9lbs at shimmed height would provide pressure relief of 70psi.

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Lance Blake The answer is in the Mellings GM LS engines catalog, you can view it for free on their website. The 10295 pump is supposed to come with the +10 psi spring installed, also included are the Standard Pressure spring and the COPO +25 psi spring. Interestingly, it looks like the COPO spring is similar to shimming the regular M-295 pump bypass spring +- .100”. When I port/shim the M-295 it raises the Hot idle pressure to +- 45-50 psi and moves the bypass opening to 65+ psi to better provide higher rpm oiling. www.melling.com/wp-content/uploads/2018/12/GM-LS-Engines-Melling-flyer-single-page.pdf

I bought a package of washers, they are the right diameter to fit nicely in the plug recess but I have to sand them to .100”. I’m not sure of the diameter at the moment but you might Google search once you’ve measured the inside of the cap and see if there’s any premade possibly hardened disc or washers .100”. JD

@@HeadFlowInc what size washers are they?

407ForRent It’s a small freeze plug, I flatten the dome on the bottom flat. All you have to do is go grab small washers that will fit inside the bypass cap. Depending on what thickness washers you buy just stack them until you get to the thickness you want. I must have edited out the part where I talked about making/buying the shim. JD

Feeler gauges are great as sacrificial shims. Used feeler gauges are almost free at garage sales and swap meets.

Usually the bypass plug comes loose without heat but recently I had a new oil pump so tight it stripped the hex head on the plug; ended up needing heat. JD

Idle pressure seems to be a debatable topic. I can say when I shim the stock relief Spring .100” it consistently yields a Cold start 60 psi, hot idle 48-50 psi and 70+ psi depending on engine rpm. I haven’t seen any stock pumps match the same psi. Plus, the stock pump is supposed to be rated as a 60 psi pump but has been proven to start bypassing oil around 53 psi which is not good at all for turning 6000+ rpms. JD

@@HeadFlowInc I agree those are good pressures, and I’m seeing mixed opinions on it with idle. I’m struggling with 19-20psi hot idle pressure , new pump and oring- I’m thinking of trying to shim the spring just to buy me some time before I condemn the motor

mathew shackelford I happen to have some washers that fit perfectly, no idea where they came from. You can measure the inside shoulder of the plug and grab washers/washer, just take a set of calipers to the hardware store. Thanks for watching! JD

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I use a small washer .100”

@@HeadFlowInc do you know the dimension of the washer though? Like .100” tall, but what about washer diameter?

@@aguitarhero007 I’ll try to find out asap

@@HeadFlowInc thank you very much

$75.00 make sure it’s a real Melling M-295 pump not the cheap eBay pumps.

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You can settle for a pump that starts bypassing oil pressure at 50 psi if you want. I show how to improve the wet flow of the pump and delay the internal bypass to match the intended rpm usage when shifting above 5300 rpms. Thanks!

You should use medium strength loctite thread locker (ex Blue) on the pipe plug for the bypass spring assembly. Torque 12 ftlb The oil pump cover plate doesn’t come with any thread locker. DO NOT over Torque it only torques to 106 inlb or 8-9 ftlb