ACDelco GM Original Equipment 251-719 Engine Water Pump with Gaskets

Bearing quality is excellent. It turns 3-4x easier than the old OEM Delco pump, but some numb nutz klutz dropped this pump at the factory. To make matters worse it was dropped right on the shaft BEFORE the protective collar was put on the fan clutch shaft. There is a very visible flat spot with tiny divots in it indicating it was dropped onto a concrete floor. Whomever dropped this should have tossed it into the reject pile immediately. If he/she drops more than one a week, someone need to go back to sweeping floors, and cleaning toilets. The paint job is sloppy with a huge drip & run in the paint. Otherwise the casting, machining and pressed in heater & heater bypass piping seems solid, well aligned and very secure. It has not been leak tested yet. GM also changed the design and eliminated the weep hole putting a cylindrical bore with a press in cap in a casting the protrudes forward from the weep hole. This will mask the symptoms when this pump goes bad. There is still a breather hole on top, but this is not the pump pictured. Update: The 17 year old water pump was rebuilt with a new seal, bushing, and bearing(s), and has been stowed away in the box the new one came in, and it spins just as nice and free as the new one, so I have a backup that I KNOW was rebuilt properly with the best materials obtainable, by the most skilled person I could find (ME). The heater & bypass pipes were checked for rust, and everything was shot with a spray of gun protectant & rust inhibitor. The casting in the old pump has minor surface rust on the machined flat plate by the impeller. The back covers, and tubing shows NO RUST, so those must have a good nickel or alloy plating on them. It is not the same casting as the new GM OEM pump. The new pump I just bought does not have a weep, or bleeder hole, but does have a breather hole above the seal. THIS PUMP SHOULD GIVE YOU 80,000 MILES WITH PROPER MAINTENANCE, AND INSTALLATION! USE DISTILLED WATER AND COOLANT<> ONLY! <<<<>>>>!!!!!NO TAP WATER!!!!<<<< If you must use tap water, flush your system. Flush your system every 80,000 miles, and check your coolant every time you change the oil, every 2000-5000 miles! Use a volt meter to check for electrolysis! Hook the black lead to the ground on you battery and dip the red lead into the radiator water. Any reading over 0.300 volts is too high, and you have an electrical problem that WILL DAMAGE YOUR ENGINE COOLING SYSTEM! Use a specific gravity tester to test the coolant. Anything with a freeze temp above -20 F and the coolant should be flushed and changed. Any boiling point under 245 coolant should be flushed and changed. If this pump had not shown signs of damage and cost $150 it would be a 5 star pump.

I'm at odds with aftermarket parts, sometimes they perform better than OEM parts, but most of the time they don't. Unless you get premium aftermarket parts, which in many cases are similar in cost if not more, I've found if you're not building an engine for performance, OEM is generally the best option. In this case, I replaced the original (1999) OEM water pump in 2021. In all honesty, the original water pump was still in good condition and just needed new seals and bearing but I figured at the age, I might as well just replace the unit. No complaints but remember boys n gals, make sure to get your mounting hardware and RTF as you only get the water pump and seals.

As always with ACDelco OEM parts, this is a very well built water pump. Yes, it costs a lot more than the $50 Chinese one, but this pump should last well past 100,000 miles. A water pump is not a part to go cheap on. If the water pump breaks and you don't notice and stop your vehicle, you can destroy your engine in minutes from overheating. If you own a GM vehicle, always use ACDelco OEM (original equipment manufacturer) parts. If the OEM part is not available, get the ACDelco Professional series part.My truck actually runs a few degrees cooler now than the old pump did when it was new. The old pump was not ACDelco and only lasted 65,000 miles. Very solidly built. Very quiet pump. Perfect fit for my 1996 C1500 Chevy truck. If you're not experienced with working on vehicles, expect this to take upwards of two hours to replace. No special tools needed. Don't forget to scrape the engine surface where the gasket rests against the engine to remove all traces of the old gasket and then clean it with a solvent like brake cleaner. Wait a bit for everything to dry. Also, don't forget a tube of RTV water pump sealant (type 22071 in Amazon). Rub just enough to barely coat the gasket on both sides, press against the pump, and then press the pump to the engine. This will form a stronger seal than the gasket by itself. Also, new pump bolts with thread sealant on them is good insurance for $10. My truck uses Dorman 902-804.Another thing, as long as you've got the system drained of fluid this is a good time to replace the hoses if they're old (ACDelco about $40 for both). If the thermostat is old, a new ACDelco one is about $10-15. Old radiator caps can leak, about $10 for the ACDelco one.

This is a brand new pump, not remanufactured and it's an exact match replacement pump. It comes with the necessary gaskets which saves a few dollars. This pump is replacing an auto parts store's remanufactured pump that only lasted about 4 years. The OEM pump lasted over 10 years and 100,000 miles so here's hoping for another 10 years. Here's a helpful trick I recently learned which made this job a lot easier. Use some brake cleaner to clean the water pump where the gaskets will go. You'll see that there's a bit of grime left on it from the factory. Then get a spray can of Permatex 80065 High Tack Spray-A-Gasket Sealant. Spray a light coat of sealant on the pump's gasket surface and a light coat on ONE SIDE of the gaskets. Wait a minute or so for the sealant to get tacky then press the gaskets onto the pump, sealant coated side to the pump. Let the sealant dry a while and the gaskets will stay in place perfectly when mounting the pump to the engine block. Do not use the gasket sealant or any RTV on the gaskets where they touch the engine block. This will simply make a huge mess to clean up the next time the water pump has to come off (perhaps when the timing chain or tensioner needs to be replaced since it's behind the pump). You want a clean, dry gasket to go against a clean, dry engine block surface.