Water Pump Packing: Bringing a Car Out of Long-Term Storage
Mark SimpsonDescription
We’ve all come to expect that various components on our classic cars require routine maintenance, but on early classic cars the maintenance schedule includes several items we’ve come to take for granted on more modern classics. One item that requires more care on older classics is the water pump. These early water pumps worked well but to create a watertight seal on the impeller shaft, packing material is used. This material requires the packing nut on the water pump to be periodically tightened to seal the shaft and in time the packing will need to be replaced.
The water pump on your classic car is a relatively simple centrifugal pump driven by a belt connected to the crankshaft, and it serves to circulate coolant while the engine is running. The pump then circulates the coolant from the pump to the engine block and head then returns the coolant to the radiator then finally back to the water pump. The most common weak links in the system are the thermostat and the water pump as they have the only moving parts. More modern style water pumps use seals on the impeller shaft as opposed to packing, but in time even these fail but are not readily serviceable by most enthusiasts. This requires simply having the pump professionally rebuilt or purchasing a new/rebuilt pump.
For owners of older classic cars it is important to understand how to properly adjust the water pump packing nut and replace the packing. Mark Simpson explains what water pump packing is and the process of replacing the packing. Simpson also discusses the process of adjusting the packing nut for both recently repacked pumps or as part or your regular maintenance schedule. On most cars these early water pumps are designed to run for years, but with a little service you’ll have them running trouble free as well.
When we did our early assessment on our car that we're bringing back from long-term storage, we had noticed that the water pump was leaking near the front. In a lot of cases, you see a leaky water pump, you assume you automatically have to replace it. Well, cars of 1940s, depending on the model or make of car, about 1940s and earlier, they used to use a water pump that had what they called a packing nut on the end. And what this is, is in order to have the shaft go into the water jacket, but in order to make that seal so the water didn't go past the bearings or bushings here and follow the shaft hub, they used to use what they called a rope packing. And what this is, this is a graphite impregnated sort of a, it is a rope kind of material that wraps around, multiple wraps around the shaft. Then, this packing nut actually presses against this material. So, you'll have multiple wraps. Sometimes, guys like to cut them one at a time and stack wraps. I prefer to just put a 45 on the end and then put multiple wraps on. But then, the packing nut serves to press this against the shaft and create the seal to prevent water coming out. It's not a perfect process. As time goes by, the packing tends to dry out. Also, just the wear from the rotating shaft will start to wear the inside of the packing. But the way the packing nut works is you can just go in here and tighten this packing nut to get it to stop leaking. And normally, what you do after you've freshly packed, you can take the water pump off, put a new set of packing in it. And you don't tighten it up completely right away. What you do is you put antifreeze in your engine and it'll leak a little bit and you just kind of tighten it up 'til it stops leaking. Then, you start your engine and you watch it and you just kind of, as the engine's running, you keep making sure that, see if it's dripping at all. If it's dripping, then go ahead and tighten the packing a little bit more until it stops leaking, and then you're set. In time, maybe one or two times during the summer, you might have to come back and just give it a little more tension to seal that up again. And eventually, over time, you'll tighten that nut to the point where it's all the way bottomed out and it's still leaking. That's when you know it's time to take that water pump back off, repack it, and you'll be ready to go again.
I have 1931 Dodge DH that has a water pump like the one in this video. Currently is leaking - finally found packing material - need to establish the size open end wrench I need to beg, steal or borrow - my steel ruler thinks it is 1 1/4 inch - my 1 1/8 inch wrench is a wee bit too small. I need to watch your. video very closely so I can determine how to remove the "ancient packing" that is imbedded in the nut. So glad you have made this "procedure" available for "old car guys" like me! My car was born in 1931 and I was born in 1940 - in some respects my Dodge is in better health than I am. I live in Finger Lakes region of New York State.