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Discussion Starter #1
Hey guys,

Im pretty new to this, i got my first bike a couple days ago, it's a 1979 CX500. When i bought the bike my friend and i checked the oil and it looked normal, but now a couple days later the oil has a lighter milky tent to it. Im nervous that it may need the mechanical seal replaced. I will post a few photos of the oil after i drained it from the bike.

Also how hard of a process is replacing the mechanical seal? I know that you normally have to take the engine out of the bike but i also saw some people on here talking about the "shep" method that may not require taking the engine all the way out?

Any tips and advice will be greatly appreciated!

Photo May 13, 9 00 07 AM.jpg Photo May 13, 9 08 47 AM.jpg Photo May 13, 9 13 22 AM.jpg
 

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Yes, I've seen oil like that!....The oil will absorb/suspend a small amount of antifreeze ,but beyond that small amount, after running the bike a bit longer, you can let the oil sit in a glass jar awhile,and the antifreeze/water will settle to the bottom, just incase you have any doubts or hopes it might be some other thing making the oil milky. But burning antifreeze is not good for the engine.

...sadly, it's not unheard of that a seller bangs a nail into the weephole,changes the oil and flogs the bike. In my case, the PO did such a fine job, I could not find the weephole until I took the bike apart! I wonder if this happened to you?

It is actually pretty easy to take the engine out and it makes it very easy to work on.
 

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The weep hole is a dead giveaway if you have a mech seal problem. If the engine is clean of oily/coolant stains just above the starter, I'd also consider a leaky head gasket.
 

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Discussion Starter #4
Thanks for all of the advice! Ill check the weep hole, i want to look for something leaking out of it correct? That would support the idea that it may need a new mechanical seal?

Also another question a bit off topic, when im removing the gas tank i should drain all the fuel out before hand correct?
 

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On my GL, you don't have to remove the fuel. Turn the valve off, remove the fuel line and the vacuum line, if so equipped. Lifts right off.
 

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No need to drain the fuel before tank removal. Just place the petcock in the off position, close the fill hole. Remove, store out of the way. Throw a short block of wood under the tank to keep the tank weight off the petcock.

The weep hole should be clear. Best seen from the left side of the bike, down low, look up toward the front of the carbs near the water pipe. Use something like a straw from a WD-40 to probe the hole. It should be open. If not use something to dig out the plug.
 

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If its not the mech seal, then the source is somewhere else. IF the mech seal is shot and weep hole is clear, then it will piddle out the weep hole.

There is definitely coolant getting into the oil. Just need to narrow down the possibilities.

First, stop riding. A recipe for engine disaster is oil and coolant mixed together.

If the weep hole is clear and not piddling, then I'd suggest a pressure test with the radiator cap off watch for bubbles.
 

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Discussion Starter #10
Thanks for all the help so far guys. I've stater the process of taking the Engine out, i removed the seat, fuel tank, battery, and radiator over flow last night. I am taking great care to remember how to put everything back together as well. I really love how much i have learned about the bike just in the couple days i have had it.

I am still having trouble locating the weep hole if anyone could maybe post a picture of where it is on the motor? The only ones i can find online already have it taken apart so it is hard for me to reference where the parts would go when assembled.

Also while i was looking for the weep hole i noticed that there is a bit of coolant/antifreeze leaking off of where the pipe from the radiator connects to the engine. It only looks like a small drop in the photo but it was pooled up a little around the bottom of where the two meet. Could this help explain how it is getting into the oil?

Photo May 14, 9 02 52 AM.jpg
 

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Micah, that could very well be drips from the weep hole. It is located just behind and under the metal coolant pipe in your picture and if the leak isn't major it would be difficult to tell where it was coming from. You could change the oil and jam a clean white rag of some sort in that spot and try to figure out where exactly the coolant is dripping from.

For reference, the picture condo posted is in the same orientation as your picture, so if you took off the pipe and the waterpump cover you would see basically the same thing.
 

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Discussion Starter #12
Kingston, thank you i was finally able to locate the weep hole. I stuck a WD40 straw in and it went about half way into the hole until it stopped, when i pulled it out it seemed to have some oil on the end. It didnt look like anything had been leaking out of the weep hole in excess, but the whole area under and around the engine is pretty grimy so it's sort of hard to tell.

Im in the process of pulling the engine out because my friend who knows alot more about bikes said he would help me replace the Mechanical seal after he saw how the oil looked. So i figure ill give everything a good clean while i have it out and it will be alot easier to spot leaks.

Would anyone be able to give me a parts list for what i would need to replace the Mechanical seal?

Thanks so much.
 

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The mechanical seal can be replaced without dropping the engine, but you will also need to replace the oil seal on the inside of the rear cover IF the mech seal is the problem. You should be able to tell when you open the rear cover whether the leak is from the seals or not. You will need OEM rear cover gasket, cam oil seal, mech seal o rings for the rear cover and coolant pipes, copper crush washer etc.
DO NOT remove the metal cup of the mech seal unless you want to enlarge the bore to fit the new style cups, just install it using Shep's method.

See the parts diagrams here:
Western Honda Motorcycle Parts Online Scottsdale Arizona

And go to the wiki, faq's and download a Factory Service manual.
 

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I had water dripping between the H-box and the tail pipes. Yes! It is dripping enough water to create a 12" diameter puddle right below the muffler clamps, on both sides. I was running some tests on my charging system, so I had it wrapped at 4 grand for about 5 seconds. I had successfully found the source of my charging issue. Then BAM…. Here are 2 puddles of liquid under the machine. So I checked the oil, and it's MILKY. I replaced the mechanical Seal approx. 1 tank of gas ago. It's not weeping at all, and I felt pretty confident with my seal installation. I didn't want to rebuild the motor till Winter, but I don't think I have a choice now. Has anyone seen this before? 79 CX500
 
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