oil breather ?

[TDC]

Hello fellow Hodakas, I just got my 1972 Hodaka wombat fired up . Once it warms up it seems to be pissing oil out of a breather plug ? there is a tiny little silver cap about a 1/4 inch on the top right side of the crank case under the carb. Any one know if this is normal

[socalhodaka]

check oil level

[hodakamax]

First check the oil level. If it has set for a very long period of time moisture can build up. When you start it the condensates mix with the oil and begin expanding as it warms up into an increasing volume of foam which blows out the breather. They should cook off but I would change the oil. Hope this helps.

Max

[TDC]

THANKS FOR THE TIP. iT HAS SAT FOR ABOUT 5 YRS SO THATS PROBABLY WHATS GOING ON HERE.

[viclioce]

THANKS FOR THE TIP. iT HAS SAT FOR ABOUT 5 YRS SO THATS PROBABLY WHATS GOING ON HERE.

Wow! Five Years?!?!? That's an awfully long time for oil to sit! Between the cold metal and the changing temps a fairly good amount of water was bound to condense on the inside covers and settle into the oil! After 5 years of sitting, I wouldn't have considered starting it until after I changed the oil! But I guess you figured that out by now, eh? ; D Victor

[tvrc18]

A couple of my bikes have sat for 5 years or longer with the same oil and they do not have moisture in them. I do start them from time to time but never run them long enough to get to warm. Was probably overfilled to start or maybe sitting outside in the elements.
Terry

[Bullfrog]

Did the oil collected on the top of the cases look like some sort of pastel colored mousse/runny frothy pudding? If so, there is water in the oil.

I don't think anyone has mentioned that an air leak between the crankcase (crankshaft area) and the transmission cavity can easily pressurize the transmission cavity . . . then rotating gears sling oil up to the bottom side of the breather vent, and the pressure forces the oil out the vent. So while being overly full, or having water contaminated oil can cause what you have seen . . . there is significant potential that the clutch side crankshaft seal may have failed. (Go figure, but 40 year old crank seals may not be trustworthy.) IF there is an air leak . . . significant engine damage could result (seizure). So keep that possibility in mind.

Ed

[hodakamax]

OK, a little technical fun here. Ed mentioned that a faulty seal between the crankcase and gearbox could pressurize the gearbox causing oil to blow out the breather. Dr. Science (me) got to thinking, how can that be? Crankcase pressures go from positive to negative on each cycle. I then looked up the cross section of that type of seal. Hmmm--If the primary seal fails first it appears that the auxiliary seal could become a one-way flapper valve and indeed pressurize the gearbox. That darned Ed appears to be right again!

Dr. Science

[bchappy]

Ed is always right

[Bullfrog]

Bill, would you tell that to my wife?

Ed

[TDC]

Well there is no moisture in the oil , it comes out looking just like it came out of the can, and it probably sat over 10 yrs, had to clean and coat the tanks and clean the carb, also changed out the stator and coil and it fires right up , seems to be running ok, was just in the dark about the oil comming out of that little valve on top.

[Bullfrog]

If the bike and oil were abnormally cold on the start up which pushed oil out of the breather vent . . . it wouldn't be too unusual to see some oil come out in that situation. But it should stop pretty quickly as the engine and oil warm up.

Do you remember this symptom from ten years ago? From your questions, it seems that this is the first time you've noticed this symptom (ever). That leads me to believe that the "dry start" after ten years of storage, combined with 10 more years of age on the seals, may have just found the end of the service life of the clutch side crankshaft seal. If oil keeps coming out of the breather vent, even with warm engine and oil, you have a prime indicator of a failed clutch side crank seal.

When I took my custom trials bike out of 35+ years of storage, I decided to run it till a seal failed. I was lucky. I got a month or so before the magneto side seal failed. Lucky because I noticed and did not seize the engine AND that seal can be replaced with the engine in the bike. I got another year before the clutch side seal failed . . . then the engine came out for a full "tear down and re-build" with new bearings and seals.

As mentioned before, rubber seals just don't last forever.

Ed

[hodakamax]

I'm backing up Ed. 40-50 year old seals are hard as a rock. We're finding all these great treasures in barns and trying to start them after decades of exposure. Seals are relatively cheap and disassembly is not difficult for the average person. I'm starting to recommend seal replacement for any Hodaka that hasn't been rebuilt somewhat recently.

Max

[hodakamax]

Just a back to the top for the breather discussion.

[---]

I have recently removed the original seals from my 1975 RD350, which has been started occasionally but not really ridden since 1981. The crank seals are pliable but worn, so they were replaced. Whether seals turn hard or don't depends on atmospheric conditions and exposure to chemicals in the oil. Ozone is the most likely thing to harden a rubber seal, and this would usually be only the magneto side seal. On mine, both were serviceable, not leaking, but showing clear wear on the seal lip, so I took them out.

The Hodaka similarly had seals that sat from 1980 to 2014 and they are fine as well. No leakage, not hard at all. While seals can and do fail from sitting, it is not a certain thing. However, prudence dictates replacing them no matter their condition after sitting for so long.

Pressure goes positive and negative in the crankcase, yes, and even if the result is neutral in pressure, the agitation of running positive/negative at thousands of cycles per minute will cause oil to creep out the breather.

There is also the possiblity of gasoline having run into the crankcase if it sat with fuel in the tank, raising the fluid level. Best practice would be to completely remove all the old oil, which requires popping off the clutch cover as well as pulling the plug, clean out what you can reach, and refilling with gear lube. If the oil still expels from the breather, it probably needs seals. A pressure test will also show the need. You can hear air pressure leaking out the dip stick hole when the cylinder is pressurized if the right side seal is compromised.