The Stovebolt Site Forums The Shop Area Engine Shop coolant leak at water pump hose connection

Sounds simple but has me perplexed. A sign of the (age).
Have a fresh 61-261 new water pump, hoses etc. It feels as though the leak is at the lower hose/water pump connection. Can't see 'cuz my head is not small enough to get in there to verify. It does not even seep or drip when cold, only when hot. Reset the screw type hoseclamp twice to no avail. WHY the leak???? Plan B is to split the connection, smear silicon sealer all over the snout and make the reconnect, but I sure would like to know why before I mess things up with silicon. Thanks in advance for your thoughts

Get an inspection mirror and a bright flashlight, and look at the small hole in the pump housing just behind the pulley. I'll bet you'll see a seep leak when the engine is hot and there's a little pressure on the cooling system. "New" is not necessarily "good". New pumps leak pretty often.
Jerry

Thanks for the lead, will surely check it out and let you know what I find

You didn't say if it was a new hose.
If it was, I found one where they punch that plastic tag holder through the hose, only this one was about 1/2" further away from the end than it should be and the hole was just beyond the casting. Small leak while under pressure.

Continuing on with this saga, I decided to remove the fan blades from the water pump pulley so I could get a closer look at things without adding insult (cut off fingers) to injury, started the engine got it hot and low and behold NO LEAK!!!!!! The whole front of the engine and bottom tank on the radiator was dry as a popcorn phart! Why me God? Checked the hose end for punctures dry as a bone, felt around the weep hole in the water pump and it was dry also. Still need some more divine guidance and leadership Thanks again for any thoughts.

What type of hose clamps are you using. If using the flat metal band worm drive type get rid of them. Switch to the wire type, tower top or crimp styles.

Get a radiator pressure test cap and pressurize the system non-running and cold and see if leak down occurs. You can also much easier see where leak is at in this mode (if it leaks).

If it does not leak cold then inspect the metal where hose attaches for micro fine crack line.

Why would the leak disappear when I removed the fan blades?

If you do the pressure test and there is no leak. You might have a bad bearing in the pump. No fan, equals less stress on the bearing and seal. If the fan is bent, or loose on the shaft center then it will shake and the seal will leak if it is not perfect. But do the leak test first.

Sometimes castings on the pump body can be a little rough. Can take a few times tightening the hose clamp for the hose to finally conform to the pump housing enough to seal. Especially if using an older hose.

I usually put just a dab of sealer on the housing before I put the hose on.

if leak stops when no fan blades are installed check the front pump seal.
Run the radiator pressure test (engine off) and pull the fan/pulley forward and push it backward when running that test.

Found da leak!!!!!!!!!!! It is at the pump/block mating surface. Apparently I didn't seal it good enough. Spent an hour looking for it with a mirror. The breeze from the fan would push the leak around to the hose connection. The leak is very small, about a drip per minute, hard to see but does make an obvious mess. Really don't want to pull the pump 'cuz its a real bear to get out, and worse to get back in while trying not to disturb a sealant bead. Has anyone had experience or recommend radiator stop leak additives. The coolant system is nonpressurized, and the block and rad was thoroughly cleaned by pros during rebuild so it shouldn't be too challenging for an additive. Thanks again for comments

Using a pour-in sealer will be a lost cause, but if you're really determined to try, "Bar's Leaks" is the only one to use. It's a chocolate-brown liquid with what looks like a bunch of rabbit poop in the bottle. Pour it in, top off with water, and go for a drive long enough to get the coolant up to full operating temperature. When (if) the leak seals up, drain the cooling system and do a quick clean water flush to get the rest of the stuff out, or the coolant will stay a nasty-looking milky color. Refill with a 50/50 mix of antifreeze and water.
Jerry