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Milky white overflow from crankcase breather - Moto Guzzi Motorcycles

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Gregg Mahin

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Hi, Anonymous and the usual suspects are:
1. Condensation builds up from parking a hot bike in a cold place.
2. Blown head gasket on liquid cooled engines.
3. Faulty water pump.
4. Blown base gasket.
5. Cracked cylinder or head.
Good luck and have a wonderful day.

Posted on Jul 05, 2020


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SOURCE: crankcase breather

If the bike sits for a while, and then you run it and shut it off, it will drip.. run it more often.

Posted on Apr 28, 2010



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SOURCE: 89 Harley FLTCU oil coming from the crankcase breather tube and

This is an age old problem for the Harley engine. In you 89 model, the crankcase breaths from behind the oil pump through a tube that runs to the backside of the air filter assembly. Most people that I know, simply remove the tube coming up to the air filter and block the hole in the air filter assembly backing plate. At the breather, they run a short hose to just behind the transmission and cut it off there. This is similar to the earlier Shovelhead engine and the way it breathes. In 1994, Harley went to the "head breather system" which was better but it still gets oil into the air filter assembly.

There is one thing I saw on the aftermarket assessories market once called a "CatchCan". The breather tube ran to it and it seperated the oil from the air and the held it in a small container to be emptied on a regular basis. I have never used one nor have I ever seen one so all I can tell you is what the book said. Matter of fact, I cannot remember where I saw it now. Custom Chorme catalog, maybe. Good Luck, Steve

Posted on Apr 30, 2010

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Excess presure in milk crank case on street glide

What year????? Sounds like a breather problem. Does the bike get fully warmed up a lot of a lot of short rides???? It appears to have moisture/water in the oil. Should not have pressure in the crankcase.

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The colling system is leaking into the crankcase, could be a blown head gasket or a crack or a section eaten through with corrosion. Check the breather pipe from the tappet cover to the air cleaner box, it will probably be milky white inside.
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I changed the oil four times and its still milky

If your oil is milky you are getting moisture in the crankcase. Does this unit set outside? make sure your crankcase vent is clear.

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18.5 hp Briggs & Staratton ELS 500 Smoking after oil and filter change and I did tilt the mower to drain the oil. So how do I get it to quit smoking?

First off, I did not write this article, but it is very informative and in depth:

Easy Lawnmower Repair"Clouds of white smoke."
This is one of the common complaints we see at the small engine shop in the Spring. The complaint is usually the same, "I put the Tractor/mower/tiller/snowthrower up for the season and it was fine all of last year. This year I take it out and I start it up and after a couple of minutes it starts blowing white smoke very heavily. Are my rings shot?"
Generally billowing clouds of white smoke are from one of two things. Either the crankcase breather has failed or the oil is contaminated.
The crankcase breather vents the gases and excess pressure from the crankcase and sends them through the carburetor to be burnt in the combustion process. Some breathers are nothing more than a reed valve that opens and closes as the pressure changes inside the crankcase from the piston's movement. If this reed breaks, bends or otherwise fails, then excess oil is pulled into the carburetor and the result is a lot of smoke. Other breathers are screen or filter type and when they become too fouled or broken down to function, same result, lots of smoke.
Diagnosis is done by looking for two things, oil in the air cleaner/carburetor and black oil soaked or heavily carboned spark plugs. Since oil is being fed directly into the cylinder, the plug will foul very quickly and probably also affect engine performance. Breathers can fail at any time, often they will fail over the winter as the oil that's built up on and around them solidifies and just generally plugs things up.
Repair is a pretty simple matter on many engines, just replace the breather. You can try turning the reed around on the reed type breathers, but personally I just replace them. Sometimes all they need is a cleaning though, so give that a try. Most breathers will run from just a couple dollars for reeds to maybe twenty dollars although a few that are incorporated into the valve cover may be upwards of thirty dollars.
Reeds and complete breathers are available from most small engine shops for most engines. Online suppliers such as Jack's Small Engines, and M&D are excellent and reliable sources for parts as well.
To replace a breather, follow the tube or hose from the back of the carburetor or air filter assembly to where the breather is mounted on the crankcase. Most are simply attached with two screws but may be under the flywheel requiring flywheel removal. If it's incorporated into the valve cover, just replace the valve cover. Some are cartridges that plug into the valve cover, very easy to replace.
The other common cause for heavy white smoke, especially in mid-size Briggs and Stratton and Kohler engines, (12-20hp) is from contaminated oil. The most common contaminant will be gasoline that has leaked from the carburetor. We have had at least one engine that had a crankcase full of water, this was probably a case of sabotage from an irate neighbor.
The diagnosis is simply to examine the oil. It should have little to no smell of gasoline and should not be overly thin or muddy brown, gray, white or chunky like spoiled milk. Do not under any circumstance attempt to start an engine with oil that fits any of these criteria. The most common cause of mid-size Briggs and Kohler engine catastrophic failure we see in the shop is from gasoline diluted oil causing the rod to overheat and break just above the crank journal.
Gas will get into the crankcase when you have a carburetor that is leaking past the needle. This leak is generally caused by either a float problem or other problem keeping the needle and seat from sealing. If there is gas in the crankcase, then the recourse is a carburetor rebuild or replacement followed by an oil change. The reason that this is such a common Spring problem is that if you leave any gas in the carburetor, it will evaporate and leave behind a varnish coating that can prevent the float assembly from functioning. Also, and even more common, the ethanol in today's fuels will ruin needles and seats, preventing them from sealing the flow of fuel off, which causes the carburetor to overflow and leak into the crankcase. Gas can also get into the crankcase from a fuel pump that's leaking, so if you have a pump, that needs to be checked as well.
These items are often the result of improper storage. I can't stress enough the importance of proper storage of outdoor power equipment.
If there is water in the oil, then several crankcase flushes with kerosene and a few oil changes may clean the engine out. However engine disassembly may also be called for to remove all the muddy deposits and ensure that the oil channels are cleaned out.
These two items are the most common causes of a lot of white smoke. We do see a few OHV engines come in and have blown head gaskets. Usually this is on a Kohler and often the oil is leaking down onto the exhaust manifold and not into the cylinder. A leaking valve cover gasket will also do this.
If the plug isn't fouled out, and the oil is normal, then check closely for a leak. Spray carburetor cleaner on the head to clean all deposits off and then run the engine for a bit. Then check for a leak again. Some talcum powder thrown onto the surface will help to spot a leak as well.
Hopefully one of these will be the solution and you won't be purchasing a new engine. Good Luck!

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1 Answer

I have a1972 shovelhead that sprays oil out the overflow tube.what could ti be

One is, there is too much oil in the crankcase. The other cause, can be stuck or worn piston rings, which let the compression "by pass" the piston into the crankcase and blows oil everywhere. Then there is a crankcase breather which may be stopped up or kinked not letting the normal amount of pressure escape, hope this helps FixYa up.

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Briggs & Stratton Vertical OHV Engine 18 hp blowing white smoke engine run great but a lot of smoke and also have oil being spit out of the black hose that come from engine to the carb.

Check your oil.

If it is overfilled, milky, or smells like gas. Your going to need to change that ASAP. It sounds like the float has stuck in the past or is still sticking, and it has flooded the crankcase with gas, which has mixed with the oil. And because it is overfilled it comes through the breather hose into the carb. This also explains the smoke most probably because the oil is spewing in the carb through the breather and being burned.

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Blowing white smoke and shutting off, shooting oil from the exoust.

Hi and welcome to FixYa, I am Kelly.

Either the crankcase is overserviced substantially with oil or... the crankcase breather is clogged. I need your ENGINE number to help you with what to do next. Without your ENGINE number... the clogged breather is usually located on the side of the engine at the valve stem base and has 2 small bolts holding it in place. Most breathers that are clogged have to be cleaned with carb cleaner and solvent.

Thanks for choosing FixYa,

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1 Answer

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oil getting on a breather can indicate excessive crankcase pressure. Check all the `crankcase breathers and the valve cover breathers.

if the crankcase has been overfilled with engine oil. The crankshaft has to "beat" it's way through the oil and thus acts as a pump and sends oil all over the internal surfaces of the crankcase.

If the engine cylinders have developed 'blow-by" they will also contribute to an increase in crankcase pressure which will be evident by oil in the breathers. The fumes / pressure in the crankcase are designed to be removed by the engine breather system, and drawn through the engine etc.

I hope this info helps.

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All engines have a breather to equalize pressure between the internal crankcase(moving parts, blow by, etc) and the outside air pressure. Heating and cooling of the motor can cause condensation (also stream crossings, rainstorms, mud puddles, etc.)in the motor which will show up in the pollution tube, bottom of the air cleaner, or breather tube as a creamy tan or gray milky liquid. It is normal and nothing to worry about unless you submerged the bike in a stream and filled the engine with water. In this case you need to change the oil immediately and get the moisture out so you don't rust up the motor.

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Start with making sure your oil lever is not over full. If it is it may be getting into the crankcase breather hose that goes to the carburetor hence the white smoke. Sometimes also you can blow a gasket in the breather system and it will do the same. Check for oil leaks in the breather system. Hope this helps. donnyb60

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