Gold 252-994 (19357961) Engine Water Pump

great pump worked perfect

Was pretty much an exact replacement for the factory part on my 2002 Duramax LB7. It came with O-rings and a paper gasket for the pump to oil cooler connection. I replaced the paper gasket with a metal Fel-Pro gasket just to be on the safe side. It took a lot of time and effort to get to the pump, so I didn't want to skimp on that piece. Order some extra O-rings for the thermostat bypass pipe and some O-ring lubricant. I cut four of them in half before I finally figured out how to get that part back in without damaging the ring. I would advise you to practice inserting that pipe without the O-ring on it until you find the position where it slips in without interference. The pump itself was easy to install. I also replaced all of the idler pulleys, belt tensioner and serpentine belt while I had it apart. That job will never be easier than it is when you have the front end stripped down to access the pump and the cost is minimal. If you are getting ready to replace your pump, watch some YouTube videos on the procedure. You will need some additional tools that you probably don't already own, and you'll see that in the videos. Free 2 day shipping was a bonus.

Perfect fit for my 2003 Silverado 2500 HD Duramax. Replacing was not that difficult, if you have the flywheel lock to prevent the engine from rotating so you can remove the harmonic balancer bolt, that is torqued to 260 foot pounds. So plan accordingly before you get started on this project. You will need to order the flywheel lock and 36mm socket for the crank balancer before you get started.

Water pump replacements are never fun in general, but the Duramax is particularly bad because the water pump is ran off the timing gears, with a stud hidden right behind the harmonic balancer. So have the right tools or be prepared for a fight. I put this on a 2005 LLY Duramax. Must haves: Leslie flywheel lock tool, AT LEAST 5 ft breaker bar (can use cheater/extended pipe) with 3/4" drive, a 12 point 36mm socket w/ 3/4" drive (try not to use adapters-can if necessary), and an exact-o/razor blade to clean old gasket off of inlet flange. Make sure the breaker bar is heavy duty, I broke one during this job and I know I'm not the only one. Important notes: This is a messy job. If coolant gets on the serpentine belt (or subsequentially one of the pulleys which then gets on the belt), be prepared for an annoying belt squeal. Best to remove belt before draining coolant and clean the pulleys after completing the job. Make sure to fully clean off the old gasket from the inlet flange. If you leave old gasket residue where the inlet connects, the new seal will be compromised and you will have a leak. From the thermostat housing there is a coolant bypass pipe that leads into it from the water pump. It's very likely you will break that o-ring removing this piece. When I took it out it came with two backup rings and a main oring, but this replacement only has one oring. I ended up getting an oring from the chevy dealership instead and leaving one backup ring on. GM PN: 94011602. Check for leaks before putting fan shroud back on by turning truck on after adding coolant of course. I like to run water through it while checking for leaks, then flushing and adding coolant. It's an expensive mistake filling this beast up with coolant and then noticing a leak that requires you to flush all of the coolant to fix.

Overall nice product. One of the O-rings broke as I was putting it together. I replaced one small O-ring and the product has worked great for about 700 miles so far.

OEM is the way to go and ACDelco is OEM This is a PAIN to replace so it is best to buy the best you can and take your time and watch videos on Youtube. Also get an extra O-ring for the bypass tube because it is easy to cut. It has been a few weeks and no leaks or overheating.

this part was installed in april 2025, it failed december 2025. the install was very extreme and expensive. i would not recommend this product to anyone. so far i can not find where i can get any warranty for this defective product.

Pro: Exact OEM waterpump replacement.. Con: Required General automotive engine repair knowledge including tools...