Packard Forum Index » Pre-War (1899-1942)

Have new water pump on, but it leaks from the packing nut. How tight can I make this to stop the leak? it is not a small drip. A good puddle on the catch pan,
I am afraid of "over tightening".
Ben

The manual advises to tighten "just enough to prevent leaks". This seems to be trial and error. You do not want it too tight. Don't run the engine with the pump dry. I've had good luck tightening the nut with fingers until some light resistance is felt, then running the engine and checking for leaks. If it drips, tighten it just a little more with a screwdriver. Don't run the engine with the pump dry or the seal will be damaged. Fill the radiator to the top. My new pump dripped at first. Finger tightening, then tightening a little at a time, then testing, got it to hold nicely, and it hasn't leaked since. Be sure to oil the pump bearings as directed. It may take only a 1/4 turn or less to get the final adjustment. Proceed with care. After a few hundred miles, or whenever a drip is seen, it may take another fraction of a turn to keep it leak free.

Thanks. So if I understand correctly. You can over tighten. And if you do it could stop the flow of coolant and dry out the pump? I have tightened a bit. Less than a quarter turn. I will drive it again tomorrow and monitor the leak and tighten a bit more taking caution. Thanks for the guidance.

If you over tighten much, it can burn out the seal and perhaps damage the shaft. If it's a little too tight, it will wear the seal faster than normal.
I'd tighten it in small increments until the drip stops, then wipe everything dry and run the engine a few minutes, then recheck.
If you have any evidence of a leak at that point give it another 1/4 turn or less, wipe dry, and try again. At that point, if the leak has stopped, I'd let it be. I'd want to check the coolant level frequently for the first few dozen miles, and give the nut another 1/4 turn or less if needed after 40-50 miles. I'd also re-oil the pump after about 50 miles or a few days.
Once the seal seats, it will usually need little attention for quite a while, but I'd look at the pump and check the coolant level every time I checked the oil, or every few hundred miles. If a drip develops after some usage, a fraction of a turn of the nut will usually stop it. If not, either the seal packing or the shaft bushings are worn out. A pump with worn bushings cannot be kept from leaking. See owner's manual and shop manuals for pictures and lubrication schedule and adjustment advice, including belt adjustment. There is a hole in the fan pulley about the size of a dime for oiling the front water pump bushing. With the hole straight up, the oil port can be accessed.

Important!! Avoid overtightening the belt! It's best to run it a little on the loose side for 50 miles or so with a new or rebuilt pump. An overtight belt will rapidly wear out the pump bushings.

By "running dry" I meant running the engine without coolant in the system. Doing that will usually immediately burn out the pump seal. If you need to start the engine with the cooling system drained, take the fan belt off. To adjust the pump and check the pump, the system must be filled with water or antifreeze.

ok. Understood. Thank you so much for the follow-up! I have my working orders now.
Ben

I have just finished putting a new packing in my water pump. The shaft was worn and the packing was very hard and brittle. I had the shaft built up and remachined and got plumbers 1/4 inch packing string with graphite and packed it in. As road conditions are not good for driving I let it run for 1/2 hour and it appears to work fine. I wont drive it till the spring to know for sure how this will last but the machining was my only cost as I made my own gaskets and scrounged plumbers packing from a friend.

I just recently did this job. My packing nut was leaking. The nut was tightened so hard by the previous owner, right up to the pump casting. It took many goes with various tools and penetrating oil, finally got a budge with vise grips. The shaft was surprisingly smooth. There was no evidence of any packing. Bought some plumber's graphite packing, filled the nut, tightened it a bit and voila! I also read that there should always be a "little" leak to assist with lubrication.