I removed the water pump from my 1963 Olds 394 engine and sent it too AG Rebuilders to rebuild. I received the pump back and it looked great. I did not inspect it closely as I was in a hurry to get the car back together. The timing cover was clean so I installed a new gasket along with a light coat of RTV and the water pump went right on. I torqued the large bolts to only 25 ft/lbs (manual shows 24-35) and the small bolts to 5 ft/lbs (manual shows 5-8). When I filled the radiator with water it leaked. It looked like it was leaking from one of the large bolts on the driver side. I removed the bolt, cleaned and tapped the threads in the block again and coated the bolt with more RTV on the threads and reassembled. It leaked again.

I decided to remove the pump and to my surprise I noticed a big crack in the steel pump housing that runs from the alignment dowel through the water housing to the outside edge. This is where it was leaking from.

I contacted AG Rebuilders and they are not sure how that happened. I did have pictures of the water pump before I sent it in and there were no cracks. The water pump also did not leak at least for the last almost 3 years I've had the car. The box they sent it in was not damaged so it did not happen during shipping. AG Rebuilders believes it happened when I tightened the bolt down since the crack is by the alignment dowel. The water pump slide on effortlessly and there was no binding. I didn't over torque the bolt so I'm not sure how I could have caused this. Either way AG Rebuilders agreed to try and swap the internals of the pump to another housing or have someone weld it up. So, the Olds will have to sit for a few more weeks while I mail the pump back.

Any thoughts on how this happened? Thanks.

Pre rebuild outside

Pre rebuild inside

After the rebuild inside

After the rebuild outside

 

I thought over torquing too. Since you got the water pump rebuilt, might they have swapped the one you sent in for one on their shelf that had been previously damaged? It could have easily been over looked.

 

It's called (simply) metal fatigue (thermal fatigue) - it happens over time (alone), esp. in areas subject to hold-down forces. Sixty three (63) years of countless engine hot/cold thermal cycles.

 

The housing could have been one they had or they didn't have that one on a flat surface when they pressed in the bearing.

 

Well, I just hope they can fix it and I don't have to pay anything else beyond the shipping back to them. The part went out today. If they have another core I could get it back in about 2 weeks. If it has to be welded they said it would take 6 weeks or more since the welder is backed up. At least I have other projects to work on. Next up is my 1958 Edsel Citation 2 door. That is getting a new trunk, hood, driver door and both front fenders.

 

Is that a dowel pin next to the bolt hole? Id bet a cold beer it cracked due to the housing being seized to that dowel while trying to break it free. Did you have to pry it off?

 

Yes, that is a dowel pin. But I did not have to pry the water pump off. Once I removed the last bolt it came right off without any effort. Also, if you look at the pre rebuild pictures I posted there is no crack in that location when I sent the pump in to be rebuilt. The crack was there when it came back.

 

I seems to me that that the crack may have occurred when the pump was re-installed.
I think the pump housing may have been binding on a rusty dowel pin
In any case, before trying to install another pump, I would suggest polishing those dowel pins with a strip of fine emery cloth or sandpaper.

 

Thanks for the comment but the dowel pins were not rusty. I cleaned them completely and there was absolutely no rust on them when I installed the pump. As mentioned, I used a scotch brite pad to polish them to a nice shine. There was no binding at all on the dowel pins when I installed the water pump. It slide on completely flush with the timing cover. I believe the pump was cracked when they sent it back to me and I didn't notice it when I installed it.

 

Ask them how they cleaned it. If it was shot blasted and then put in a tumbler then that could have done it. Tumblers can wreak havoc on cast iron.

 

When I spoke with them the rebuilder said he bead blasts the pump housings to clean them. They should receive the pump by Monday so I'm hoping they are able to replace or fix it. Thanks again to everyone for your help on this.