Water pump leaking oil

[DirtieGirtie]

I bought a second VMAX a week ago. I haven't even gotten started making my first one road worthy yet because my primary bike, 2012 M109R, has been having intermittent ignition issues. So I bought this VMAX on the cheap as it seemed to need very little to get her on the road.

I got back from a ride on Sunday morning and heard a sizzling noise after shutting the bike down. About 5 seconds later I heard it again. There was oil dripping onto the right side exhaust pipe. Tracing it back, it seemed to be originating from the bottom of the water pump housing (not the cover). I tried to find a seem to see which gasket was leaking... but it was coming right through the casing!!! It was weeping/seeping right through the aluminum casing. The water pump cover to casing was not leaking (which would only show anti freeze, and this was definitely oil). The gasket between the water pump housing and the engine case was not the location... it was about 3/4" above that seam. I could see oil seeping right through the housing, form a drop, and then roll down and sizzle on the exhaust.

I actually heard the sizzle when I took it for a very short ride after flushing the clutch slave cylinder. But there has never been any drip under her so I didn't think anything of it.

The same thing happened this time. I came back to her an hour later thinking I would see a spot on my driveway. Nope. No spot and no more oil seeping through the housing.

Anyways, I took the water pump off and it seems like the inside of the housing has a tiny stress crack - really just looks like a line or scratch - right where the seeping occurs. Which only seems to happen when hot. I thought about trying to repair it - maybe grind off a bit of metal on the inside to form a dimple and then fill it with JB weld. But then I thought about the possibility of a chunk of cured JB weld floating around my crankcase and decided to buy another off of ebay instead.

I don't have any question or anything. I've just never experienced a microscopic crack in a cast aluminum part like this so I thought I would share.

 

[Fire-medic]

My understanding is that aluminum die-castings have more of a possibility of developing porosity than cast-iron, for-instance. Yamaha actually developed a method of forming high-density aluminum castings, done under pressure.

Apparently, the best method to deal with that would seem to be welding, either MIG or TIG, I assume. I've used JB Weld on the outside of engine cases and have had luck with the durability of the repair, but I never did it on the interior of a side case cover. It sounds like getting a used case off an auction site may be the cheap-shot to a fix, but finding someone who could weld that for you would be the ticket to using your existing part again.

At my friend's shop, they're always piecing aluminum engine cases back-together after some carnage. God may save souls, but they save engine cases.



Work is ongoing in this pic.


They love the air-cooled Suzukis (GS1000, 1100, 1150's) and Kawasakis (Z1, KZ900, 1000, 1100) and yes, the '69-on SOHC Hondas.

 

[DirtieGirtie]

Very cool! I wish I knew how to weld. That would definitely be my best option. I was also considering drilling and taping the area with a 'faux' drain plug that was glued in place with JB weld. Well, the ebay part will be here on Tuesday, so I'll see how good/bad that one looks and go from there.

 

[Fire-medic]

I'll share another method of repairing an engine case, another of my friends showed me. It was a side-of-engine case threaded hole where the shouldered casting broke. Instead of welding, he used a NPT plug where he drilled-out the threaded hole, then threaded the case, and used red loctite to hold in-place the NPT plug. Then he drilled and threaded the plug. The casting was fairly-thick at that location. It worked great. That's similar to what you were thinking-of.

 

[02GF74]

I thought about trying to repair it - maybe grind off a bit of metal on the inside to form a dimple and then fill it with JB weld. But then I thought about the possibility of a chunk of cured JB weld floating around my crankcase and decided to buy another off of ebay instead.

That's the correct decision. Why risk damage to the engine to save a few $$$ - almost certain what you paid is less than potential engine repairs or replacement.