Melling 10540 pump review
 

I bought one of the Melling select pumps, the M54DS that is supposed to have better gears and machining than the regular M54DS.

In a word: Meh.

For $110, i expected better machining. I started blueprinting it this weekend. I don't have many pics since I didnt have my phone in the shop that day. But here is what I found:

The good: relief seat looks excellent. It comes with the standard 5/8 ball but the better green spring that's been parallel ground. Relief cap is really nice. Pump inlet and outlet are well machined and outlet passage doesn't have a bunch of core shift.

The bad: Machining of the pump cavity was marginal. The plate mating surface had big machining grooves. The bottom of the gear cavity had criss-cross cuts. Typical non-flat mounting bolt head surface has to be cut down smooth. Gears look nice, but ends were rough and had to be smoothed on a glass plate with 400 grit. No dimple in end of gears.

The ugly: End plate was pure dogflop. Bent, not flat at all. Had a huge outward bow that could not be sanded out. Endplay disaster leak-o-matic.

I'm going to rework it, but would not buy one of these again. For the amount of work it'll take me to straighten it out, buy the Butler Pro Pump or one of the Precision Oil Pump's blueprinted pumps.

Appreciate this info, thinking I'll call Butler when I'm ready. Sorry you had to go through this but posting your experience is really helpful to the rest of us. I was thinking about that pump with the same expectations. Now, i'll just call Butler.

Here's what I had to do to get this pump "right"

Run a sanding roll through the outlet passage to clean up casting flash

smooth floor of pump cavity by making a sandpaper disc and putting it under a gear to burnish the floor of the cavity. 400 then 600 grit

Smooth the walls of the pump cavity to remove high spots and burrs that were dragging on the gear tips. Jewelers file, then 600 grit sandpaper.

Grind the mounting surface flat where the head of the mounting bolts sits

Run the lid mating surface over a glass plate with 320,400 and 600 grit to set gear end-play to .0025".

Deburr gear teeth, both ends and tips. Tips were rough from dragging on sharp lead-in on pump cavity. Smooth both ends on 600 grit.

Buy a thicker end plate from Precision oil pumps, then glass plate that with 320,400,600 grit to clean up machining imperfections and make sure it's flat.

Replace stock relief ball with 9/16" ball. Shim spring with .055" hardened washer, ground down to fit inside spring cap. Verify ball to seat fitment for leaks

Clean everything with brake cleaner and a nylon brush.

Install gears with clevite engine assy lube on shafts and pump cavity. Sprits rust inhibitor spray into assembly prior to installing bottom plate.

Drive in the MIlodon bolt-on pickup with a brass hammer. Then find out the bolt hole didn't line up because of the thicker plate. So I had to cover the pump body with a cloth and then use a die grinder to elongate the mounting hole on the pickup. Wash clean with brake cleaner, blow dry. Remove end plate from under pick-up tab, replace with thin plate. (to cover pump gears during deburr operation). Deburr tab both sides, clean out any debris. Remove thin plate and reinstall thick plate. Id think that most bolt-on pickups are not going to fit with the thicker plate. Be prepared to elongate the hole.

Drop red loc-tite on screw threads and torque to 20 ft/lbs. Verify pump spins smooth.

I'm not sure even Butler puts this much work into an oil pump. It'd be good to compare the innards of on of theirs to a stock MS54DS.

Are you going to check the pressure before it gets installed?

Flat plate over the outlet with two bolt holes and one 1/8th" NPT hole to hook up a mechanical guage. 1/2 quart of oil in a pan is plenty to see where the relief opens up.

BTW.. DO NOT use heavy oil for this test

Clay

For another 50 bucks or so u could just get the Precision race pump and be done with it, and no screwing around :)

Even the Butler pumps do not cut the mounted bolt holes flat. I still have to do that and then some to those pumps.

The only real difference I could see between the M54D and the 10540 pump is the 10540 is black phosphate coated. I asked Melling what that coating really does anyway. His answer, "it keeps it from rusting". I pointed out to him, the fact that oil pumps spend their life submerged in oil.

Oh yea the phosphate coating is worth $45 bucks, right? whoopteedoo!

Here are pics. Check out the before and after on the pump body.

The precision bottom plate has pressure oiling to both gears.

Good idea on verifying relief operation. I'll do that when I'm closer to install.

Gotta love those mounting feet.

Picture #4 The cast iron boss at the bottom of the pump is machined at a given angle, for a reason.

Tom V.

You mean where it mates to the engine block? I didn't mess with that. I only flattened out the area that the bolt head pulls against so it has decent contact. The factory casting just has the edge of the bolt heads providing all the clamp load.

Thanks Chiphead for this informative thread. I need to get a pump to replace the 40 lb one in my engine.

A forum member years ago recommended the Luhn pump to me if I ws going to race my Pontiac (great pump but above my pay grade).

http://www.luhnperformance.com/pontiac.html#tv-1s

And that reason would be?

It places the pickup in the correct location in relation to the bottom of the oil pan.

I use the 60Lb pump and put a .100 hardened washer between the end cap and the spring this gives me about 65-70 psi

Dumb question. Where do you guys source your hardened washers from?

ARP makes a metric washer that fits the spring retainer perfectly.

A bit more expensive by about $70.00, but the Nitemare pump, covers all of these areas of concern. Pretty happy with the one I just put into my engine.

Chiphead said .055" washer to make up for the smaller diameter 9/16" ball. Are you saying .100" washer with the 9/16" ball to increase pressure a bit more?

The ball is only 1/16" smaller in diameter but does that make it set even a little deeper into the pocket where it might need a bit more shim? 1/16" = .0625" which seems like the shim size necessary just to keep pressure the same with the smaller ball? I always wanted to try the 9/16" ball but didn't want to tear the pan off and correct a mistake in pressure if I got it wrong.

I'll have to admit that it took me a LONG time to get used to seeing lower oil pressures with these engines.

So when and where does a stock replacement Melling pump NOT make the grade in one of these engines?.....

Stock replacement 60PSI with no modifications? From what I've seen, it's 3 things (at least)

Relief ball hanging in bore and giving abormal low pressures
Erratic oil pressure near relief setting (oil pressure dancing 45-60 PSI with hot oil above 3000 RPM)
Endplate isn't flat, so would result in oil pressure loss due to leaks between pump body and endplate. Also impacts gear endplay. I'm guessing could cause lower oil pressure at hot idle.

After reading through my original write up, I forgot to show where I pressure tested the pump in the block. I made a block off plate out of an old filter adapter and screwed an oil pressure gauge into it. So I was measuring deadhead pressure while running pump with drill. I filled the pan with cheap 10w30. I got 65 PSI while running the pump with a cordless drill. It stayed at 65-67 no matter how fast I spun the drill. The pressure might be a bit higher when actually running, because the pump RPM would be higher and pressure wouldn't be slamming the ball off the seat, like it does testing deadhead.