My Second $500 K75 Project

[Smudgemo]

Good call on the fan motor - I'll wait until it's running and I service the cooling system.  But I'm going to order a new fuel vent line and the wires because I'd rather mess around with fuel once and be done with it.  I'm not in a hurry.

This weekend I mostly just cleaned things up some.  While giving it a wash, I was reminded that the rear cowl lid had a broken tab and a PO held it in place with gorilla tape.  I got this idea somewhere, and it worked perfectly for a non-abs bike.


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It's just a bit of kit to mount a fender on a bicycle that I bent 90*.

[Smudgemo]

So I got it running today.  Lots of smoke initially (I did shoot some fogging oil in the cylinders last weekend), but it seems to run as well as my RT.  Who'da knowd fresh gas vs old gas/varnish/water was the ticket?

The one thing I'm not clear on is why so much moisture exited the muffler when it was running.  I noticed some dripping where the header and muffler connect before I tried to start it, and assumed it was somehow accumulated from sitting outside, but it seems kind of like oily coolant.  I need to get some distilled water to fill the system and let it get up to temperature, I guess. 

[Smudgemo]

I decided to add distilled water to see what would happen, and there's coolant getting into the oil.  The level in the sight glass was milky looking and went up, and the watery exhaust didn't quit.  I'm going to drain the oil and coolant and take a look at the pump.  Maybe the prior rebuild was done poorly or the shaft was reused in poor shape.

The engine had good compression when I checked, so wasn't ready to blame the head gasket, but the wet and smoking exhaust is making me think maybe.

[Smudgemo]

This morning I dropped the oil pan while investigating the pump, and yeah, that ain't so great.


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Still not sure this is the smoking gun, but the pump drive shaft is damaged, though not terribly.  Anyone have experience?  The weep hole had a blob of sealant in there, but wasn't attached and didn't seem like enough to block drainage.


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I also found a thread this morning where someone was getting large amounts of coolant into his engine and he apparently had a cracked block.  https://motobrick.com/index.php?topic=11379.25 Figured I may as well try and eliminate that as a problem so I turned a plug to fit the block, disconnected the radiator hose on the left side and poured a liter or two of water into the radiator hose.  The plug doesn't seal perfectly so I put a cup in the catch pan to segregate it from any real problems and went in to have lunch.


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So at this point, the engine had compression, it runs well, but it's getting a lot of coolant into the oil.  Is it possible the pump rebuild was done poorly and it really is the issue?  The only thing that looks iffy so far is the pump shaft and my desire to spend $200 on a replacement part, not to mention $50 for another rebuild kit.

[TriSpark]

Yay, it's running! Congratulations on getting that far with it so quickly. It's a great feeling when they come back to life again.

Re-reading the initial posting, and looking at all that water in the exhaust gas and the sump, I'm leaning towards the water pump repair being a bodge job. I think you are on the right track with that. Someone here who has done a water pump overhaul before should have the necessary know-how on that job.

Will the pump shaft polish up to remove the damage, or is too far gone? Did the seller say who'd done the pump seal work - them, or a bike shop?

[Duckbubbles]

I don't believe the water/oil pump can introduce coolant into the engine oil system.  If you will notice there is about a 10mm gap in the cavity between the waterpump seal and the oil seal inside the combined pump.  That cavity is where the coolant or oil leakage past those seals drains from at he bottom front of the oil pan.  The only place I see where that can happen is through the head gasket or a cracked block as mentioned before.

Frank