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Bevel Gear Case and Water Pump Gasket Replacements/ISO Mechanic?

benkopischke8934

Member
Member
Hi all, I am a new owner and new member of COG. I have a 2001 C10 with 54,000 miles on it. A month after purchasing my bike has developed a sizeable oil leak. After posting a couple of times on the Facebook group the general consensus is that it is coming from either my water pump, or bevel gear drive gasket. I am now planning to attempt replacing both gaskets, however I do not have a manual and cannot find anything in the tech pages about the bevel gear drive. Any pics or instructions pertaining to this would be greatly appreciated. Or if anyone knows someone who works on C10s near Des Moines IA or is willing themselves to come help me diagnose and identify the issue. I am optimistic about being able to do it myself as I am fairly knowledgeable mechanically but would love the opinion or help of someone experienced with this particular bike or issue. TIA!
 

connie_rider

Member
Member
Inspection;
Remove the plastic, and clean the area, and let it dry.
Then put it on the Center stand, crank the engine and look it over for leaks.
If it's the water pump, there is a small leak hole below under the water pump.
A mirror would be very useful.
If you have an oil leak there, remove the water pump and replace it, or replace the seal.
If you don't see a leak there, put the engine in gear and let the rear wheel rotate.
If the gasket is bad, the rotation will help push the oil out.

Instructions on how to do either repair is in the Manual.
I think Bud can send you access to a Manual online.

Ride safe, Ted.
 

ONOBob

Member
Member
Inspection;
Remove the plastic, and clean the area, and let it dry.
Then put it on the Center stand, crank the engine and look it over for leaks.
If it's the water pump, there is a small leak hole below under the water pump.
A mirror would be very useful.
If you have an oil leak there, remove the water pump and replace it, or replace the seal.
If you don't see a leak there, put the engine in gear and let the rear wheel rotate.
If the gasket is bad, the rotation will help push the oil out.

Instructions on how to do either repair is in the Manual.
I think Bud can send you access to a Manual online.

Ride safe, Ted.

I've been trying to buy a factory C10 manual for some time. I have a Clymer.
I'll reach out to Bud for this on line one.
Thanks Ted.
UR alright, I don't care what they say about ya.
Bob
 

benkopischke8934

Member
Member
Inspection;
Remove the plastic, and clean the area, and let it dry.
Then put it on the Center stand, crank the engine and look it over for leaks.
If it's the water pump, there is a small leak hole below under the water pump.
A mirror would be very useful.
If you have an oil leak there, remove the water pump and replace it, or replace the seal.
If you don't see a leak there, put the engine in gear and let the rear wheel rotate.
If the gasket is bad, the rotation will help push the oil out.

Instructions on how to do either repair is in the Manual.
I think Bud can send you access to a Manual online.

Ride saf

Inspection;
Remove the plastic, and clean the area, and let it dry.
Then put it on the Center stand, crank the engine and look it over for leaks.
If it's the water pump, there is a small leak hole below under the water pump.
A mirror would be very useful.
If you have an oil leak there, remove the water pump and replace it, or replace the seal.
If you don't see a leak there, put the engine in gear and let the rear wheel rotate.
If the gasket is bad, the rotation will help push the oil out.

Instructions on how to do either repair is in the Manual.
I think Bud can send you access to a Manual online.

Ride safe, Ted.
What would be the best way to get in touch with Bud for the manual?
 

bobct

Member
Member
I have to ask, did you do an oil change or add oil before this leak appeared? With an oil drain from both drain holes and a filter change it will take 3 liters of oil. Some new owners don't know about the second drain bolt and overfill the crankcase which may cause leakage. Others use the sight glass to add oil until it looks right which is very deceiving/inaccurate and can cause an overfill.
Alternator oring and crankcase to airbox breather tube could be other places for leakage, especially with an overfilled crankcase.
 
Last edited:

benkopischke8934

Member
Member
I have to ask, did you do an oil change or add oil before this leak appeared? With an oil drain from both drain holes and a filter change it will take 3 liters of oil. Some new owners don't know about the second drain bolt and overfill the crankcase which may cause leakage. Others use the sight glass to add oil until it looks right which is very deceiving/inaccurate and can cause an overfill.
Alternator oring and crankcase to airbox breather tube could be other places for leakage, especially with an overfilled crankcase.
Oil change after it started leaking, both plugs and filter change
 

laker9142

Member
Member
Hello, I recently had the pleasure of R&R the front bevel drive on my C14. I'm assuming the procedure would be the same as a C10. The oring on the water pump was hard and flat enough to cause an oil leak, but I didn't have an oil leak. However I did develop an oil leak on the first two attempts of going back together. The first attempt, I assumed the oil leak was caused by reusing the gasket,.... not true. So after getting a new gasket and still leaking oil for the second time I was scratching my head. So upon retorquing all bolts for the 3rd time I finally noticed the smaller diameter bolts would always require more tightening. and so it was that they were stretching, although they would click the wrench at the proper value, again and again. The large dia bolts are good and strong. Replaced the small bolts with grade 8 and all is well.

Except now I had a severe water leak thru the water pump weep hole. Ended up rebuilding the water pump. I successfully installed a new mechanical seal in the water pump, but without a lathe and skills this would not have been possible. If there is a next time Ill have a water pump ready to switch out.

Its all straight forward wrenching except for what I said, and releasing the drive shaft by pushing that little pin, if the C10 is the same.
 

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bobct

Member
Member
As long as you didn't overfill the oil capacity I would start pin pointing the source of the leak as Ted said, take off the plastic under belly and lower side cover and start the search.
Water Pump including its weep hole (when I had a coolant drip from the WP weep hole it landed on exhaust pipe), gear shifter, alternator to crankcase connection, crankcase breather tube to bottom of the airbox (probably not this breather tube puking oil into the airbox if oil level is correct) and bevel gear case.
If you end up changing bevel gear gasket make sure you get the newer metal based gasket.
 
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