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  #1  
Old 10-27-2018, 05:29 PM
n233va n233va is offline
 
Join Date: Jul 2014
Location: Prescott, AZ
Posts: 33
Default Marvel Schlebler Floats for Rotax Engines

Hi All

I installed the MS floats on Oct, 3rd. Out of the box the pairs weighed over 7 gms. , 7.46 and 7.42 to be exact. I called MS and inquired about the weight and the fact that Rotax specifies no more than 7 gms. Was assured that they tested these and they worked at that weight. So I installed. Today Oct 27th, in route to Marana AZ. The engine started running rough, intermittently. The exhaust gas temp on the right carb side would drop by 200 to 300 degrees. After a brief period of time all ran smooth and the temps returned to about a 40 degree split. I turned around and headed back to Prescott, AZ. On the way back, I had repeated instances of intermittent engine roughness. Each time, the exhaust gas temp on the right side would drop at least 200 degrees and there was a rather strong smell of gas in the **** pit. Upon return, I dropped the bowls on both carbs for inspection. The right set of floats appeared to be sticking slightly. If I gently shook the bowl they would release and float normally. The exhaust was black and oily. I replaced the MS floats with a usable set of Rotax floats in both carbs. Upon run up, the engine ran smooth but above 4000 rpm's the oil pressure dropped dramatically. I shut down and dumped the oil. It was evident that there was gasoline in the oil. I also removed and drained the filter. Closer inspection of the MS floats compared to the Rotax floats revealed that the hole in the floats for the pin were smaller in the MS floats and did dot have a brass sleeve as the Rotax ones do. It is my opinion that the MS floats(s) on the right carb stuck and flooded the engine with raw fuel. When they became un stuck due to vibration they floated again for a period of Time.

I replaced the oil in the engine with fresh Aero Shell Sport Plus 4 an rand it up again. This time, oil pressures were normal and remained so through 5000 rpm static on the ground.

Based on my experience, I would strongly caution against using the MS Floats. My hope is that the cylinders were not washed enough by the fuel to have caused any damage to the walls. Compressions felt normal but I will get gauges on the tomorrow. And bore scope the cylinders 1, 3 . Wanted to get this info out asap.

If you have questions, I can be reached at boblid@icloud.com. If you leave a phone number I will be happy to call you back.
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  #2  
Old 10-27-2018, 05:46 PM
DHeal DHeal is offline
 
Join Date: Sep 2006
Location: Windsor, California
Posts: 737
Default

What kind of fuel were you using? 100LL? Auto 91 with 10% ethanol? Auto 91 without ethanol?
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David Heal - Windsor, CA (near Santa Rosa)
EAA #23982 - EAA Technical Counselor and Flight Advisor; CFI - A&I
RV-12 E-LSA #120496 (SV w/ AP and ADS-B) - N124DH flying since March 2014 - 700+ hours (as of Nov 2018)!
VAF donation through June 2019.
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  #3  
Old 10-27-2018, 06:30 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,149
Default

Question - did you run the electric fuel pump for any length of time prior to engine start, or for that matter, after engine stop? Normally not a problem and in fact desirable, but if float sticks, perhaps electric pump could cause carb overflow into intake manifold and if intake valve was held open - raw fuel could entire cylinder.

Be a stretch - but possible...
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #4  
Old 10-27-2018, 08:14 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 243
Default

Quote:
Originally Posted by n233va View Post
Hi All

I installed the MS floats on Oct, 3rd. Out of the box the pairs weighed over 7 gms. , 7.46 and 7.42 to be exact. I called MS and inquired about the weight and the fact that Rotax specifies no more than 7 gms. Was assured that they tested these and they worked at that weight. So I installed. Today Oct 27th, in route to Marana AZ. The engine started running rough, intermittently. The exhaust gas temp on the right carb side would drop by 200 to 300 degrees. After a brief period of time all ran smooth and the temps returned to about a 40 degree split. I turned around and headed back to Prescott, AZ. On the way back, I had repeated instances of intermittent engine roughness. Each time, the exhaust gas temp on the right side would drop at least 200 degrees and there was a rather strong smell of gas in the **** pit. Upon return, I dropped the bowls on both carbs for inspection. The right set of floats appeared to be sticking slightly. If I gently shook the bowl they would release and float normally. The exhaust was black and oily. I replaced the MS floats with a usable set of Rotax floats in both carbs. Upon run up, the engine ran smooth but above 4000 rpm's the oil pressure dropped dramatically. I shut down and dumped the oil. It was evident that there was gasoline in the oil. I also removed and drained the filter. Closer inspection of the MS floats compared to the Rotax floats revealed that the hole in the floats for the pin were smaller in the MS floats and did dot have a brass sleeve as the Rotax ones do. It is my opinion that the MS floats(s) on the right carb stuck and flooded the engine with raw fuel. When they became un stuck due to vibration they floated again for a period of Time.

I replaced the oil in the engine with fresh Aero Shell Sport Plus 4 an rand it up again. This time, oil pressures were normal and remained so through 5000 rpm static on the ground.

Based on my experience, I would strongly caution against using the MS Floats. My hope is that the cylinders were not washed enough by the fuel to have caused any damage to the walls. Compressions felt normal but I will get gauges on the tomorrow. And bore scope the cylinders 1, 3 . Wanted to get this info out asap.

If you have questions, I can be reached at boblid@icloud.com. If you leave a phone number I will be happy to call you back.
Iím guessing MS has indicated they will follow up? Iíve got two pair waiting to be installed.
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  #5  
Old 10-27-2018, 08:20 PM
n233va n233va is offline
 
Join Date: Jul 2014
Location: Prescott, AZ
Posts: 33
Default MS Floats

91 Octane with ethanol. Electric pump on continuously. Have not contacted MS at this time. Event occurred today 10/27. Will contact on Monday. I plan on asking for a refund and return the floats. Let you know the outcome of my communications with MS.
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  #6  
Old 10-28-2018, 11:07 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,149
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Slow day here and I've been thinking about this long-running float problem. I wonder if floats could be made from a hollow plastic blow mold... sort of like plastic soda bottle? Plastic would have to be resistant to gasoline and alcohol. I would imagine if the float was hollow the plastic wall thickness could be sufficient and still have good buoyancy. The brass slider tube would need to be incorporated into the molding process. Envision a bobber used for fishing - very buoyant.

Are the new MS floats a solid material or are they hollow as I describe above?
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #7  
Old 10-28-2018, 10:29 PM
John C's Avatar
John C John C is offline
 
Join Date: Mar 2005
Location: Moundridge, KS
Posts: 140
Default MS floats solid?

Solid. MS has video showing a float being sawed in two and still working.
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Moundridge, KS
RV-9A 90512 N6699 Sold
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  #8  
Old 10-29-2018, 05:16 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 1,149
Default

Quote:
Originally Posted by John C View Post
Solid. MS has video showing a float being sawed in two and still working.
Solid - that's what I thought. I have emailed Marvel-Schebler with suggestion to make floats with hollow injection mold technique per post #6 above.

I'll post response soonest...
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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