An engine’s oil pump dispenses the pressurized lubricant that prevents opposing surfaces from contacting one another, carries heat away from certain areas, and maintains minimal valvetrain lash when running a hydraulic camshaft. Bolted to the block and residing deep within the oil pan, it operates so reliably that it could be the most disregarded component of any engine.
Contrarily, the oil pump may be the most critical component within an engine. Conscientious hobbyists closely monitor their Pontiacs’ in-dash gauges, knowing that most likely all is well within the engine if hot oil pressure doesn’t dip dangerously low at idle and pressure at normal cruising speed remains steady. If the pump can’t perform its task, it will not only lead to significant bearing damage or complete engine failure, but ultimately total engine destruction.
The traditional gear-driven Pontiac V-8 oil pump is a simple design that is quite reliable. Discontinued by Pontiac years ago, Melling Tool Company manufactures today’s replacements, and we spoke to a company insider about its Pontiac-specific offerings. We then contacted Butler Performance, a Pontiac performance leader, to gain a better understanding of high-performance Pontiac oiling requirements and learn more about its new Pro-Series oil pump. Here’s what we learned.
Melling Tool Company presently...
Melling Tool Company presently produces four oil pumps for Pontiac V-8s, and M-54D is quite possibly the most popular. Similar to the 60-psi unit Pontiac originally used in its high-performance 400 and 455 engines, M-54D contains a 50-psi pressure bypass valve. It is marketed as Melling’s stock-replacement oil pump and fits all Pontiac applications. The M-54DS (shown here) includes a pickup screen and sells for less than $50 from most Pontiac builders or mail-order retailers.
The Pontiac V-8 oil pump is a positive-displacement rotary unit that utilizes two spur gears to distribute pressurized oil throughout the engine. As the gears rotate, their teeth separate and creates a partial vacuum that draws oil into the pump body through the inlet pickup tube. Oil then fills the spaces between the gear teeth, where it’s carried to the output side of the pump and forced out through its discharge hole.
Pressurization occurs when discharge flow meets the resistance associated with forcing oil throughout the engine. Oil-flow volume increases along with engine speed, and a sprung ball-type bypass valve regulates maximum pressure. Once the preset amount of pressure is reached, the bypass valve’s check ball is forced off its seat, redirecting excess output flow back toward the inlet side of the pump.
Pontiac used three distinct oil pumps in its V-8 engines, and they are often referred to by approximate maximum pressure ratings of 40, 60, and 80 pounds per square inch (psi). The 40-psi unit is the easiest to distinguish by its 5⁄8-inch-diameter inlet opening, and it was commonly used in two-barrel and low-performance four-barrel applications. The 60- and 80-psi units feature a ¾-inch inlet opening for increased volume capacity. The 60-psi was most often used in 400- and 455-inch performance engines. The 80-psi pump, which is immediately recognizable by its longer bypass-valve nut, was used in the ’73-’74 Super-Duty 455 (and the non-production Ram Air V).
To differentiate its oil pumps,...
To differentiate its oil pumps, Melling routinely affixes a small metal tag with an embossed part number. The M-54F pump is a high-pressure replacement similar to the 80-psi unit commonly associated with the Super-Duty 455. It retails for around $50, but does not include a pickup screen, which is available separately.
The oil pumps that Pontiac originally specified for its engines were very reliable and rarely troublesome. New replacements were available from dealership parts departments for a number of years. As certain part numbers were superseded or discontinued, only a handful of oil pumps were available when Pontiac discontinued the entire line several years ago. Fortunately, at least one company presently produces new Pontiac oil pumps, and its history is quite rich.
The Melling family started Melling Tool Company in 1946, when it developed its M-10 oil pump—a stock-replacement unit for ’37 six-cylinder Chevrolet engines. Its first aftermarket high-volume oil pump was introduced in 1952 and revolutionized the industry. Many high-quality aftermarket oil pumps followed.
Melling remains well respected today for its world-class engineering, product development, and distribution capabilities. It operates 11 facilities in North America and Brazil, and supplies OE-spec and high-performance fluid pumps, including oil, water, and fuel for gas and diesel, transmission, and hybrid applications. It also offers a full line of camshafts and valvetrain components, cylinder sleeves, expansion plugs and bearings, engine hardware, and tools for the engine-building industry.