Motorcycle Repair: 1985 Kawi 750 Vulcan-coolan in oil, coolan, head gasket

Question
Hi Mark;
I have just purchased a 1985 Kawi 750 Vulcan and have run into a few problems, to say the least.
One day after work I went out to start my bike and it did not want to start, backfiring, not catching, etc., seemed like a timing problem to me.  Finally it fired and away I went thinking that when I got home, about 10 miles, I would look into it there. While pulling the last hill something let go with a bang and I got oil spray on my left leg.  The bike made it home the last 1/2 mile and holly smokes was it hot, coolant was boiling in the overflow tank.  It would run but sounded horrible, only ran for a few moments before I shut it down. I thought it was in the top end and so did an automotive mech. buddy of mine.  The guy I bought the bike from put 1500.00 into a top end rebuild less than 700kms ago.  My initial thought was to tear it down and then determine if I rebuild or replace. I have a shop to work in so this isn't a problem.  I started the engine removal following the steps in the manual I purchased.  After removing the oil screen or rather what was left of it I noticed that it was tore apart and the one end was chewed up.  I thought this was a major moment and decided to replace the plug minus the spring and screen to see what it sounded like. After refilling with fresh oil it fired right up sounding like it should, it still seemed to have a bit of a slap in the top that I should be able to adjust out, any ideas?. The next day on a very cold morning I rode to work again and the bike overheated in 10 miles.  I took the bike back to my shop and removed the engine to see what the heck was up. When I dropped the oil it was full of coolant, not good.  This made me think that a bad head gasket or warped or crakked head. There doesn't seem to be any leakage around the head however once the engine covers were removed the top definately had coolant in the top end.  On inspection everything seems to be Ok except the water pump, it's pooched, way to much wobble in the impeller shaft. When reading through the manual it appears that there are a couple of oil seals as well as water seals.  Could the coolant in the oil be from the water pump being pooched?  I have the engine out and on the bench already.  I plan on replacing the water pump, thermostat and oil screen assembly.  Is there anything else I should keep my eye out for? I do most of my own work but it's usually on cars/trucks this is my first bike in about 10 years so it's been awhile.
Thanks for any help/advise that you can give.

Mark Bowers

Answer
Hi Mark,

Thanks for the detailed description of the problems.

First thing to do is a leak-down test. This will determine the source(s) of the leak. (Should have done compression and leak-down while engine was still in frame.) That's ok, we'll get around that. For now, do the leak-down and advise what percentage readings you obtained and where you heard the escaping air. We can do compression check later. If you do not own these tools, check with your local AutoZone or other car parts stores for loaner tools.

Coolant can blend with engine oil from sources such as: worn seals, cracked cylinder and head surfaces, and defective gaskets. Yes, it could be a result of the defective waterpump.

Tip: Cooling systems are air-free by design. Anytime you service a cooling system, purge the air from the system with a purging tool such as MityVac's AirEvac tool. Air lowers the biling temperature of coolant. If air settles around the waterpump, coolant stops flowing.

There are a variety of causes for engine overheating. I would need to perform a few tests to diagnose the cause of your MC's problem. We'll go from here. Use my email address: mshively1@woh.rr.com

Respectfully,
Mark Shively



Overheating:

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug incorrect
IC ignitor trouble

Fuel/air mixture incorrect:
Main jet clogged or wrong size
Fuel level in carburetor float chamber too low
Carburetor holder loose
Air cleaner clogged, poorly sealed, or missing
Surge tank duct poorly sealed

Compression high:
Carbon built up in combustion chamber

Engine load faulty:
Clutch slipping
Engine oil level too high
Engine oil viscosity too high
Drive train trouble
Final gear case oil viscosity too high
Brake dragging

Lubrication inadequate:
Engine oil level too low
Engine oil poor quality or incorrect

Gauge incorrect:
Water temperature gauge broken
Water temperature sensor broken

Coolant incorrect:
Coolant level too low
Coolant deteriorated

Cooling system component incorrect:
Radiator clogged
Thermostat trouble
Radiator cap trouble
Thermostatic fan switch trouble
Fan relay trouble
Fan motor broken
Fan blade damage
Water pump not turning
Water pump impeller damaged