I got tired of oil mist on my propeller and prerotator on my tango, the mist was coming from the vent tube..So I coiled up the tube about 6 turns, zip tied it together and drilled a 3/8" hole in the back side of the airbox next to the breather hole that comes from the cranbkcase.
Stuck the hose in and now if it slobers a little bit it just gets burned by the engine, nice clean prop now.
The stock Yamaha air box has that very same basic setup. Oil from the valve cover goes into an oil-air chamber inside the air box that drains the oil back into the oil tank while sending the vapor into the carbs or throttle bodies.
The only down side to the stock setup is that certain conditions (such as overheat) can cause more oil than can be separated from draining back into the tank, causing excessive amounts of oil to enter the cylinders through the carbs or throttle bodies. If enough oil gets into the cylinders, it can stop the engine or in extreme cases, blow a head gasket or cause other damage.
Life is good, if you never overheat. Another option that some folks use is to route the vent tube into a container. The container becomes a pre-flight maintenance item, as it must be periodically emptied.
...or maybe the oil vapor is just coming from a smoker??
On two occasions I have had my overflow bottle fill up. The second time, it was enough to cause the low oil level warning to come on. I believe that ambient heat and the size of the condensation tube contribute to the problem. It seems that the oil does not condense fast enough and over flows into the over flow.bottle. I notice on a yamaha powered Dominator in Anahuac, the owner has a long tube up the mast with a K&N type crank case filter on it. Perhaps the long tube up high could allow the oil/air condensation to occur and flow back down the tube to the oil tank. I like the idea of making a coil, but, with the overflow tube, sorta like the coils on a still.
After a bit of experimenting, I ended up with a similar change. Firstly, my "condensation chamber" is high, with a K&N style breather, and secondly, my overflow pipe connects to the breather hose down low by the tank, thereby forcing any air/oil bubbles to climb the long tube to the chamber. I have a bit of vapor overflow, but it isn't much at all.
...and I agree, excessive overflow is heat-related.
Tom and Jon, My 2019 model has the overflow chamber/bottle welded to the back of the mast it drains back into the oil tank but also has a small vent tube on the top, do the earlier models also have this, or did you have to make your own?
Scott, I have the tank on the back of the mast. It seems that it's capacity to condense the oil is limited on hot days and long trips. I am going to add a copper tube and run it along the mast up to a breather. The copper tube should allow for further cooling and gravity to drop the oil back into the system.
I had to make my own. I think Tom's may have the welded chamber. Mine originally had a paper filter for the throttle bodies sandwiched between two plates with the vent tube T'd to drain back to the tank and venting to the throttle bodies. It was a problem once oil built up on the inside of the paper filter and increased the vacuum in the vent tube. So, I went to Omni air filters and made my own air/oil separation chamber.
I have not heard of the RX-1's having this oil build up problem.
Do the Apex's have this issue all the way around?
I doubt anyone using a stock airbox would be aware of the issue. Oil doesn't build up as such, in fact, in the stock Yamaha setup (Apex or Nytro), it burns more oil. Tango got away from the stock airbox from the beginning, though they build two or three with the stock box. It turns out that the fuel-injected models run more efficiently with a different airbox setup, as documented by K&N, OMNI and others.
The original airbox was designed to improve performance with the Yamaha carburetor setup. Yamaha carbs "burp" air pressure when a cylinder fires. This "burp" causes a pulse that is required by the next carb at high rpm to improve input pressure (like a mini super-charger) at the start of intake. For this to happen, the airbox has to be both hard-sided and a specific size internally. Use a miss-sized airbox or individual carb filters and you loose LOTS of horsepower and run very rich....on carburetor engines.
The fact they burned excess overflow oil in the cylinders, was, and remains, an out-of-sight-out-of-mind thing. The fuel injected engines use the same airbox, though they don't need or use the pulse.
Bottom line for excess oil overflow: If you don't use the stock box, then you have two choices. One is to route excess overflow into the cylinders via whatever you are using for an airbox (and it better not have oil-soluble components) OR deal with it via oil-air separators. I like OMNI filters and an oil-air separator, myself, but the Tango airbox with an oil-air separator works as well.
If you are not using the stock airbox on a carburetor engine, then you probably should unless you are VERY sure of the design of the airbox you are using. Tango's airbox works with the carburetor 3 cylinder engines, but is probably not the right spec for a 4 cylinder. And again, if you are using the stock airbox, you are burning any oil overflow. If you are not using the stock airbox, then that overflow must be dealt by other means.
It is my =opinion= that excess oil overflow is usually due to excess heat combined with high RPM. Not necessarily enough heat to cause a warning light, but certainly more than normal for a relaxed cruise. I have learned that the oil pump in the Yamaha is remarkably powerful, so it isn't a surprise that a little extra heat at high RPM would cause excessive bubbling. It is no surprise, then, that in hot weather at high RPM oil "usage" increases...especially if using the stock box and burning the excess.
The crankcase vent is routed up and into the top of the air box. The inside of the air box has a small catch filter area allowing the excess to drip back down the vent tube back into the cc vent. I guess I will see if anything happens when I get r flying and running down the runway at speed.
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This isn't that kind of issue. You probably won't experience this in the pattern or near the airport. It is more like the kind of thing you find during a long cross-country when you are pushing for speed on a very hot day with a heavy load.
These are cold weather engines. It isn't a surprise that they don't care for high RPM for extended periods on a blistering summer day. I'm thinking the ultimate solution would be the addition of an oil cooler for summer use. The stock oil cooler is a bit weak if you ask me, and frankly I think much of its design is more to keep the coolant warm and protected from freezing than to cool the oil.
I think the same thing and that tiny cooler is surely not up to a long hot day of CC at high air speed. I will keep an eye on this once I have it up and flying and a cross country. (Oshkosh would have been a good run) Since i am using an RX-1 in a single place I may never see a problem.
That 4th cylinder is not even working hard at the gyro's weight. You all only have 3 and are in a two place with more weight and drag surface.
Will let you all know how it pans out for the RX1 vs. it's 3 cyl. brethren.
Just before I moved back to Texas, Alex I discussed the slobbering problem. One day in his shop he had me the white air oil separator in this photo. My friend Bobby and I installed and tested it today. It catches the overflow from the breather tube on top of the Tango stock square tube. However, I may make it the primary and leave the square tube out of the equation. Unfortunately, my water pump impeller failed after only a year and I am in need of a new pump or rebuild kit. I was told on FB that these plastic impellers fail frequently on several Yamaha engines When temps get above 200 degrees, so I am adding temp gauge.. Apparently, you can replace the plastic one in the pumps with this one https://www.partzilla.com/product/yamaha/8ES-12450-01-00?fbclid=IwAR2IGCXsfQ9zOMj7Q8dlgMkXbj0PwZpv4UrzudaCwlFthKsR3OTS0ASZDMs
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...who would care? And that's a comment...
Um..."Who would care?"....that'd be a question, rather than a comment.....just sayin'....
After looking at Gregory Bury and Aziz Musa's Tangos, who both have the stock setup with the metal air oil separator, I now think that my problem may have been related to the head gasket. Gregory has not seen any slobber and he does not have a catch bottle at all. However, he only flies solo and does not "yank and bank" or fly long cross country flights. Aziz uses a catch bottle, but, his slobber is minimal, once again flying mainly solo and not at higher rpms for extended periods. When I was flying solo, short flights, my slobber was minimal and a bit creamy. However, on 2 long cross country flights the slobber was excessive, filling the catch bottle with a dark mostly watery/oily fluid. I think it was from coolant coming from a very minor leak in the head gasket. The leak probably started last year when my first plastic water pump impeller cracked at the end of a flight.
I am installing a temperature gauge so I can throttle back if the temps start going up and I also have a billeted impeller on order that I will install into my water pump. Additionally, I am adding an oil cooler.
I have re-routed my oil-air separator and am slobber-free currently. I ran the line from the valve cover DIRECTLY to the oil tank with a "T" connector for air pressure/bubble release down at the tank end of the line, instead of at the valve cover. My separator can is up above the valve cover on the mast (similar to stock Tango).
Yesterday, I flew with Casey and full fuel to Piedmont, Alabama and back on a dual cross-country ride. It wasn't a South Texas day, but it wasn't cool either. No slobber at all.
Tom, what kind of water temps were you seeing on the trip?
some oil cooler options..
https://www.summitracing.com/parts/der-13260
https://www.spelabautoparts.com/collections/radiator-oil-cooler/products/evil-energy-universal-10-row-10an-aluminum-engine-oil-cooler-transmission-cooler-racing-oil-cooler-raditor
https://www.jegs.com/i/Derale/259/15405/10002/-1?gclid=EAIaIQobChMIy5r22MbR6QIVCrbICh3ogQh8EAkYASABEgKMyPD_BwE
I installed the sensor on the thermostat side of the oil cooler to what I thought was the return hose back to the cooling system. In that location I can see the temp gradually rise as the engine warms up and it never gets above 154 degrees and stays between 147 to 149 during climb out and cruise. The stock sensor is located on the thermostat.
Think that for monitoring purpose the location that Tom chose is fine. The engine thermostat is set at 160 F and the temps he is seeing and the rate of increase is fine, uncalibrated within 5 degrees. My point being that monitoring temp at this point will allow a baseline to be established and watched going forward.
I agree that the important bit is a reference. Kurt's isn't accurately calibrated, but it lets him know what normal is and isn't, allowing him to adjust his pilotage accordingly.
I monitor the RX1 with two temp locations. One is mechanical and the other through the EFIS.
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Where is the EFIS sensor located?
sensor is in the middle of the two coolant pipes on the valve cover. That wire is terminated at the efis control unit.
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Still having problems with oil everywhere. NOT out of the vent, front of the engine wet after each flight, Lost 10 oz of oil in 30 min flight.
changed valve cover gasket, tightened all oil and vent lines, checked all venting, washed everything, went flying, came back and engine covered in oil, (yuk!) gotta find the leak!
a cam in the problem area?
hope you find it. How annoying is that?
will check a few things today....
The tank I added still has a very small amount of mist, its very minor. However, I may modify the stock Tango air box with some K&N Filters on each end and go back to the original design with the over flow going back to the air box. The Tango air box already has two holes one for the crank breather and one for the mist overflow.
OK I was able to locate the leak, it was leaking around the two half-moon sections of the valve cover gasket on the front of the engine. I removed the new gasket, cleaned everything and reinstalled the gasket with some 3-bond gasket sealer.
Everything A-OK, also I looked in my toolbox and found an air/oil separator for an air compressor and installed it in the vent line, no spewing oil, no nasty oil mist, all seems to just great!
and it happened to me a few times while road racing. It is due to the high rpm's and constant higher internal case pressures looking to release that pressure. Under normal use it has less of an issue relieving it and when you add the oil to the mix it builds pressure up quicker due to the combined mass (oil) in the air pressure. Yamabond was also the solution. But only applied to the head surface and half moons making pulling off just the valve cover easier leaving the rubber gasket in place. Good find...did the camera trick expose the issue?
I thoroughly cleaned the entire area, got it good and dry and flew for about 5-7 minutes and came back to see where it was wet, and was able to find it, if that did not work I was going to do the camera thing.. Problem was after flying for some time, when I landed oil was everywhere, even on top of the engine, so just finding where it was coming from was the issue because everything was wet.