Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

[Donald H.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Below is more inform in an email exchange with Melling tech support. The M55 DOES NOT have the heavy duty casting but the 10553 and 10553ST do. And as he states below, the "the volume and pressures specs have been retained".


The M-55 casting was changed years ago and works fine in stock applications. In extreme use such as racing and any solid engine mount application The Melling Select series cast iron pumps (10550ST through 10555ST) are recommended as they use the older more robust castings.

All of the Select pumps have been upgraded to end in ST and contain the Shark Tooth (helical) gears instead of the spur gears. The volume and pressure specs are retained.

[James W.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

I will be most likely sending the M55 oil pump back to Rock Auto after it arrives. If everything that has been nsaid about the M5 being true (breakage issues) it is not something I would install in my '65 L79 or '64 L75. I do not need the oil pump at this time, but always like to have a spare in my parts inventory for when I need it. My L79 was rebuilt back in 1984 by my dad's machinist/mechanic and reads correcly during all idling and driving conditions using the SuperTech 10w-30 oil. My L75 was rebuilt in 1981 and has a high pressure/volume pump in it as it pegs the gauge at cold start.

It would be interesting to do a test on the new 10553ST pump to see if it is in fact correct in gauge pressure.

James

James

[Gary B.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

James,

I would be willing to bet that the history of breaking that Dan mentions occurred with the M55 pumps before Melling redesigned the M55 casting, or with what Melling describes as race use. Maybe Dan can tell us more about the time period when breakage of the M55 pumps was happening. You just have to think that Melling would not let such a problem persist.

Gary

[Jack H.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

James,

I would be willing to bet that the history of breaking that Dan mentions occurred with the M55 pumps before Melling redesigned the M55 casting, or with what Melling describes as race use. Maybe Dan can tell us more about the time period when breakage of the M55 pumps was happening. You just have to think that Melling would not let such a problem persist.

Gary

In my mind it was the other way around...Melling/Others redesigned the pump casting to save costs/material and that's when the breakage occurred in solid lifter and hi-rev applications. The pump is a heavy chunk of metal which is cantilevered off a single mount boss, and where they removed material is exactly the place that the design is most vulnerable. I don't think that the original OEM pumps that came in these old cars had this wimpier, reduced section design.

I do agree that I too am surprised that Melling would allow such an issue to persist, which is why I'm particularly interested to see what the RockAuto pump that James just ordered actually looks like. I would hope that it would not be the weaker redesign, but the fact that Melling recommends the 10553 for solid lifter and hi-rev applications suggests otherwise.

[Dan D.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Hi Gary,

I heard about pump breakage about 10 years ago when I was rebuilding my engine. I did not have any specifics on how, or on what conditions breakage occurred, but I argued with myself that if one has $2-3k (or more) invested in a valuable period correct engine, then why not spend a few more bucks to insure you have a good pump, one that will not break. The cost differential back then was not as much as it looks to be now. But if one did break you would most likely blow the engine before you realized you had no pressure. Our old cars do not have a warning light - just a gauge that no one looks at most of the time while driving.

What Melling told Don is probably correct, i.e. racing or hard mount. I don't believe there is any other difference between the two, but if it is only a little additional cast iron it should not cost that much more. Sounds like they are ripping us off. Also, if the new pumps are this 'shark tooth', meaning helical cut gears, that would be a much larger cost adder, but definitely a better pump, but also one that we don't need, except perhaps in racing applications.

With regard to the spring, my pump did not include a green spring - I had to order it, based on a phone call I had with Melling at the time. But like I said, I still think the pressure is too high. Oil pressure was increased by GM sometime it the mid 60s (don't remember when - or why).

I remember Duke writing about oil pressure a few years back. I remember he said the Melling green spring was higher than the original GM green spring. Perhaps he will chime in here. This would probably not matter too much, except that our older Corvettes have the tach drive and fuel unit cross shaft distributors, and high presure can blow out the seal, alough mine so far at least is okay. My car is pegged 60psi cold, dropping to about 30 when hot.

Dannnnnnnnnnn

[Joe L.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Below is more inform in an email exchange with Melling tech support. The M55 DOES NOT have the heavy duty casting but the 10553 and 10553ST do. And as he states below, the "the volume and pressures specs have been retained".


The M-55 casting was changed years ago and works fine in stock applications. In extreme use such as racing and any solid engine mount application The Melling Select series cast iron pumps (10550ST through 10555ST) are recommended as they use the older more robust castings.

All of the Select pumps have been upgraded to end in ST and contain the Shark Tooth (helical) gears instead of the spur gears. The volume and pressure specs are retained.

Don------


If the 10553T pumps actually maintain the volume and pressure of the original GM pumps, then I do not see why they would not be perfectly acceptable for use. The revised gear design, by itself, does not seem to be a negative factor to me. In fact, I presume that Melling found the revised design to be an upgrade over the original design or they would not have gone to it, especially in their premium pump line.

The question is what are the "volume and pressure specs that are maintained". If it's the volume and pressure specs of the original GM pumps, then all is well.

[Gary B.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

?..The question is what are the "volume and pressure specs that are maintained". If it's the volume and pressure specs of the original GM pumps, then all is well.

[Ed H.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Don't take this as gospel... I believe I tried the pump of interest and found that it would not fit in the pan, ie it was too deep. I will attempt to find the paperwork to confirm. This was 4 years ago.

[Dan D.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

You have to have the right pickup Ed. Don't remember what the P/N is, but it should still be available. Someone here, I'm sure, can help you out on this. You need to set the depth and tack-weld it in place so it can't move.

Dannnnnnn

[Gary B.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Don't take this as gospel... I believe I tried the pump of interest and found that it would not fit in the pan, ie it was too deep. I will attempt to find the paperwork to confirm. This was 4 years ago.

Ed,

As Dan says, you have to get the pickup/screen that is the correct length for your oil pan. When researching Melling oil pumps a few days ago, I found a table with the standard pickup, plus a number of optional pickup screens, nearly all of which I believe were longer than the standard pickup, for use with high capacity oil pans.

Gary

[Ed H.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

LOL, it was a bit ago, but I'm confident that Aubrey would have had the needed pickup were all that what was needed. But, as I said, don't take this as gospel!

[Joe L.]

Re: Melling 10553 vs 10553ST oil pumps; is the 10553 discontinued?

Ed,

As Dan says, you have to get the pickup/screen that is the correct length for your oil pan. When researching Melling oil pumps a few days ago, I found a table with the standard pickup, plus a number of optional pickup screens, nearly all of which I believe were longer than the standard pickup, for use with high capacity oil pans.

Gary

Gary------

The GM screen/tube was GM #3830080 but it was discontinued quite some time ago. Melling #55S3 is virtually identical and will fit and function perfectly. This screen is applicable to all 1963-74 and 80-82 Corvette small blocks but has no other non-Corvette applications.

By the way, if a high volume pump is used there may be a fitment issue.