Review on Melling M 54F M54F Oil Pump by Timothy Spinner

The pump works normally, but the tolerance inside the pump is not correct. As a result, the pump cannot withstand the high oil pressure when idling. I replaced it with a stock pump and have about 30 pounds of oil pressure at hot idle compared to the Mellings pump which is about 19 pounds hot at idle. When you rev the engine, the Melling pump instantly jumps to 60-plus pounds hot, but just doesn't carry the 30-plus pounds at hot idle like the stock does. FYI, the stock pump turns about 45 pounds when hot. Comparing stock 90,000 mile pump gears to new Mellings, you can see the obvious difference in spacing. The stock All Mileage pump still has a tighter fit between the gears in the pumps. That's the only difference I see between them. I believe the Mellings pump has a high pressure bypass that creates higher pressure as the RPM increases. It's a good pump for the price, but I always prefer good oil pressure.