Just completed water pump rebuild. I never really understood the weep hole in water pumps. All I knew was that when it starts leaking.....get it fixed!!
For those of us who are(were) in the dark I'll explain.
Within the water pump housing there are actually 2 chambers, the engine oil/crankcase, and the coolant. Separating these two is a casting(wall) in which the pump shaft runs through. On one side is oil & the other coolant. In between is a small void area where the weep hole is located.
There are two seals; one which keeps the coolant from migrating into the engine crankcase and the other from keeping the engine oil from migrating into the coolant. when either seal fails the only place for it to go is the void/weep hole area. The Mystery is Solved.
Now, about the rebuild. Its not rocket science but there are a few pitfalls to watch out for the first of which is the impeller shaft damper & seal. The best way to separate the impeller from the shaft is with a press. Not having one I used 2 blocks of wood on top of a vise & a heavy hammer. I had problems with the wood blocks as they kept moving around & I eventually slightly bent several impellers because of the instability. In retrospect I would have been better off setting the impeller directly over the jaws. I was able to straighten out the impellers but this added time to the process. It was a real bugger getting it separated & I wound up heating the top of the housing a bit to finally separate it. The other major headache was driving the other half of the seal(the mechanical coolant seals are a 2 piece set) & although I used a penetrating catalyst I should have let it sit for 30 to 60 minutes. I'm very confident it would have just popped out without too much effort. You insert a narrow drift pin from the bearing side & tap around the seal housing to drive it from the bore.
(hindsight is often the best teacher) I'm not going into all I went through to get the housing out of the bore.......lets just say it was ugly!
Buy a can of "PB PENETRATING CATALYST" also known as "FABULOUS BLASTER". This one tip will save you hours & much aggravation.
The parts I ordered from the dealer are as follows: yamaha pt# 11H-12438-10 coolant seal set; yamaha pt# 1WG-12439-00 pump cover O-ring; yamaha pt# 93101-12173 pump oil seal. The only thing not ordered was the engine side O-ring. I didn't realize I wouldn't get both of them when ordering. As it turned out it's in good condition. Barring the issues I had I think its like a 90 minute to 2 hr. job tops.
Sorry if I went a little long but I needed to explain the curve balls. All of us sooner or later will be faced with this repair & the more we know the better it will go.
