New member of the 'Sinker Club' (carb floats)
 

After about 125 hours on my RV-12, I was beginning to think I would be one of the lucky few without carb float problems....I was wrong! Doing my night currency last week, I noticed the smell of fuel in my cabin for the first time. Also, my idle had been gradually getting rougher. After shutting down for the night, I opened the oil tank door on the top cowl and the fuel smell was very strong. With a flashlight, I could see standing fuel in the drip tray! I removed the top cowl and dropped the float bowl.....sure enough, the floats were mostly submerged. After letting them dry, I weighed the pair and they were 11.4 grams. I then checked the left carb floats, they were not as bad yet, but still over weight at 9.5 grams. I just ordered 2 pair of the latest PN, 861188. Wow, $300!! I guess I have a new and expensive 'consumable', this engine is 1.5 years old with 125 hours. Based on everything I have read, I am not confident that the new floats will last any longer. Maybe it's the ethanol in this California fuel. I just wanted to add my experience as a data point. :(

Paul

Can you take quality photos to show all sides of a single float? Maybe lay a metric scale next to the float so size can be inferred. I want to see if I can get an injection mold company to prototype a hollow plastic float with brass actuating pin and brass guide tube as integral part of the design. Maybe we can make our own floats that would be hollow and float like a fishing bobber.

Maybe wishful thinking, but I will spend some time contacting injection mold people if I can get a decent set of photos of the existing Bing float. I'm even thinking about possibility of 3D printing.

Lots of companies do prototyping and small production runs.

A quick search found this company...
https://www.xometry.com/injection-mo...RoCC2MQAvD_BwE

Other than the rough idle, were there any other symptoms - excessive mag drop on runup, perhaps? The reason I ask is that my RV-12 buddy has been fighting that and his front spark plugs keep getting carboned up. He just had his carbs "adjusted".

Hi Jim, I would be happy to send you a pair of these, I won't use them again. You idea sounds like a worthwhile effort!

The only other symptom I had was the obvious smell of fuel in the cabin, and very strong in the engine bay. I would assume my plugs don't look great right now, since it would be running so rich at idle, but I have not pulled them. Everything seemed great for my first 120 hours, I guess the floats just slowly absorb fuel until they are just too heavy. My left carb (floats weighed 9.5g) was not dumping fuel into the drip tray yet, at least not noticeably, but I am sure it was just a matter of time. The right side had standing fuel in the drip tray, so that additional 2g seemed to make a big difference in the bouyancy of the floats.

Paul - I'll send you PM/email with my shipping address.

I've already contacted a friend who is a premier machine designer and he will draw the part. Also contacted a friend with high quality 3D printer to ask his opinion.

Maybe hollow float could be made with rotational mold process using same red plastic as used for approved gasoline storage cans. The two piece-mold could have ability to hold pre-cut brass tube in correct location in each mold half and also brass actuating pin on the mold parting line. When mold opens and part is removed the access brass tubing length would be hand-trimmed.

Fun thinking about this stuff. I've been retired five years but this is right up my alley...

I guess I got to feel sorry for all the guys having float issues. The cost of replacing is insane. Only to find out the replacements fail too.

I have to tell you that I have my original floats that came with my RV 12 kit that I finished and flew in 2009. I now have 1000 hours on them. I weighted them yesterday . They all came in under 3 g . 2 where at 2.98 and 2 where at 2.99.

I have never had a problem with them. The same floats are used in the Rotax 503 Bing 54 and 23 years of flying with those I never had a heavy float .

Some where something changed and in my experience I don't believe it was 10% ethanol.

Must have been a change in the way they where made or what they where material they where made of.

Brad Stiefvater
124 BJ first customer built RV 12 to be airwothied and fly

Do you run Avgas or auto fuel? With 10% alcohol?

I use auto premium with no ethanol 90% of the time in the 12 .But I did use 10% ethanol in the 503 for years .Same floats.


Brad

MS floats
 

Paul, will you be looking into the Marvel Schebler MS80-430 solid epoxy floats that there has been much discussion here on VAF as an alternate?

Wow Brad, 1000 hours on your original floats and they still weigh under 3g each!! They should be sent to the Bing Hall of Fame!!

I wanted to order the MS floats, then read the post from 'n233va' from a few weeks ago. He had a major issue with them, he said they have a smaller hole, and don't have the internal brass sleeve so they would hang up on the posts. So I just decided to try the latest PN of the Rotax (Bing) floats and see what happens. I am hoping we get more data about the MS floats.

I emailed Marvel Schebler as follows:

It has been reported in VansAirForceForums that your new MS80-430 Blue Epoxy Floats for Rotax 912 Bing 64 carburetor stick on the float bowl vertical guideposts and don?t control float level correctly.

Do you offer lifetime warranty against fuel absorption and weight change? In other words, do you guarantee that your floats will not succumb to long duration exposure to both Avgas and 93E10 auto fuels? Do you also guarantee that float level is correctly maintained when using your new floats?

I don?t want to purchase your new floats and discover same problems as Bing floats in a couple of years.

--------

I'll report Marvel Schebler response soonest...

Thanks Jim, looking forward to their response. I am sending you a pair of my heavy floats today.

I find it crazy that this is happening. Even more crazy is the fact that Bing could charge money for replacements after some users have only had them for a few hours. This seems like it should be easy for Bing to resolve and at no charge as they clearly have sold a defective product. A gas float that absorbs gas and no longer floats?

I am still early in my build so hopefully this will get resolved so by the time I buy my powerplant I won't have the issue.

Rotax 912ULS carb floats
 

I concur w/ MCEMS. I am unaware of a diff. yr., design, etc. I had a 914T, sold w/ 325 TT, no float probs. 100TT on 912, prior to changing out to 912ULS now 210TT = no prob.on either. I use 91 no ethanol. However, I have a TX friend who has changed out 1 set after another, app. on yrly. cond. inspection...& yes, flies +++ hrs. annually, fresh fuel, never in storage, also 912ULS :confused:

I've emailed them twice about this - they're not responding ...

We'll give them a few days and then call them on the phone. They do answer the phone?

I just had another thought... just spitballing here... It seems that a lot of guys are "collecting" heavy floats. As an experiment, I wonder if maybe a hole could be drilled into the side of a Bing float and the inside hollowed out with a Dremel tool bit? Once complete, a patch could be applied with Proseal. Perhaps several grams of material could be removed and float would again be spec weight. I have to stop eating pizza for breakfast...

Well, Dr Frankenstein...you should have a couple to play with on Friday, according to USPS :)

another data sequence
 

My engine came with 861 182 floats in 2015. Per Service Bulletin I replaced them 10/2016 with 861 184 (2 dots) before ever running the engine. After a smooth first flight in 9/2016 I found fuel dripping onto the floor under the left carb. Left float pair weighed 7.21 g, right pair weighed 6.70 g. Replaced all four with 861 185 (3 dots), each weighing 2.79 g dry.

Engine began starting rough after about 20 months and 140 hours in 93E10 gas. Did annual insp. a few weeks ago at 24 months and 160 hours. Found evidence of long-term leaking from left carb inside cowling. Floats were resting firmly on bottom of float bowl and weighed 6.64 and 5.62 g each. I am surprised the engine didn't run worse. Right carb floats weighed 3.47 and 3.63 g and seemed OK. Replaced all four with new design 861 188 floats at $300. Have fingers crossed.

I have a lot of faith in Marvel-Schebler based on several decades of owning factory airplanes with MS carbs and never any mention of float issues. But it seems my engine won't tolerate floats weighing much over 7 g per pair, the limit that the Rotax manual suggests. Can't convince myself MS floats are OK based on what several of you are reporting. I want to.

Are these just VANS phenomena?s ?
 

Are engines around the world are having similar issues and is Bing fast tracking fixes? Or is this like the Vans voltage regulator rectifier configuration phenomena ?

Great info Charlie, your experience is very similar to mine. I just received my new floats today, they are the same PN as yours, 861188. I weighed them and confirmed that they are physically the latest Rotax floats per their 2017 Service Bulletin (no dots and an internal brass sleeve). Like you, it was $300 for the 2 pair and I am hoping for the best...maybe these are better than my originals.

I'm beyond disgusted with this float quality issue. I had Lockwood perform the 200h inspection/maintenance on my carbs in March. They replaced all four floats at $150.95 a pair.

At 44 Hobbs hours, 7 months one failed while I was fortunately on the ground doing some other maintenance. It was at least 6 grams and was on the bottom of the bowl. The side pin in the failed float is actually loose and can be twisted around in the float. Clearly Q/A failure. The floats they installed in March were from two different batches and the one that passed looks like it has a rougher surface than the failed float. I'm trying to contact Lockwood to determine to whom this needs to be reported. Just unacceptable.

I quickly shopped around for a replacement and found some interesting things. First, cannot even find them on the Lockwood website. CPS, the other authorized Rotax dealer in California has them listed at $131.75 a pair. However, the winner is Aircraft Spruce where they are listed at just $93.50 a pair. You can even buy singles from them. Back ordered in the East, so I ordered them from the Western warehouse and just got them. However, I see this morning they are on "indefinite backorder" in both locations.

????

Hi Brent, good info. Yes...it should not be this difficult!! So the pair at Aircraft Spruce for $93.50 is PN 861-184, an older style. According to Rotax, the latest version is 861-188 per my prior post. So CPS shows the correct PN, with a price of $131.75/pair (they now show out of stock, because I just purchased their last 2 pair from what I can tell). Anyway, Spruce and CPS should have identical pricing because AS owns CPS, they are in the same building in Corona, CA. I am hoping this latest version will last at least a year!! Happy Thanksgiving!

Per post #17 above... Paul Straub is sending me two heavy floats which I should receive tomorrow. I have good selection of carbide burrs for my Dremel and a digital scale with 0.01 gram resolution. I plan on milling a cavity into the float and remove enough material to bring float back into <3.5 gram spec. I have some fresh Proseal which I can mix in correct proportions. I've been thinking about material to form the lid for the milled cavity. So far possibilities are thin brass, aluminum, or carbon fiber. I hope to mill the cavity from the top side of the floats so sealed surface is above the "water line" so-to-speak.

Jim,
I think the cavities will eventually fill with fuel through the porous material of the float, and you will be worse off than before. Just my opinion.
Alex

more info tidbits
 

In my original post (#19) there is a typo. I replaced the original 861 182 floats per SB in 10/2015 not 10/2016. The engine had never been fueled at that point. When I experienced fuel dripping onto the floor after the first flight in 9/2016 the floats had been immersed in fuel for only a few months and the engine had been run only about 3 hours. That suggests strongly that the problem is that the floats had some material flaw and could not tolerate being immersed in fuel. Engine vibration or heat radiated up from the exhaust pipe seem like logical possible culprits but exposure had been minimal at this time of failure.

My newest 861 188 floats all weighed 3.13-3.16 g dry. Another forum thread says new Marvel-Schebler floats weighed 3.7 and 3.8 g and as I explained before I don't think my carb would function properly with floats that heavy, unless the pin location is different. I got the 861 188 floats from Leading Edge Air Foils. I usually deal with Lockwood but they did not have any in stock. Phil Lockwood told me a couple weeks later that he did not have information on the Marvel-Schebler float development. This surprised me since Phil has been one of the Rotax gurus for a long time.

Also mentioned in that other thread is height of the fluid surface in the float bowl. But it looks to me like the fuel inlet for both the main jet and the idle jet is a brass orifice situated low in the float bowl, in which case height of the surface in the float bowl would make little difference. My problem seems to be floats so saturated that they don't close the needle valve and the float bowl overflows into the carb throat. Oddly, neither the carb synchronization nor the idle speed seemed to change during all the leaking.

Charlie -

Welcome to the club...

I haven't had a chance to carve up Paul Straub's heavy floats.

Paul S. - Do your new floats (with shortened brass slider tube) float at correct height in the carb bowl? Noticeable difference from the heavy floats?

Hi Jim, good question, I didn't think to fill the bowls with fuel and do a visual check. I installed 4 new floats (2 pair of PN 861188) It was raining all day yesterday, so the only testing so far has been a 5 minute engine run. No rough running at idle and no signs of any fuel leaks or overflow. They all weighed in at 3.1g - 3.2g before installation, so I would assume things should be fine for the next year or so.

pin position
 

My new, dry 861 188 floats (shorter brass tube slider) all floated with lower side of the pin just touching the fuel surface. Again, 3.13-3.16 g each when dry. This seems to be about as good as it gets. The engine once again starts instantly and smoothly, and runs smoothly at all RPM. 168 hours on it.

Any news on the Bing float situation?

Sinkers not floaters
 

Thought I would add another Data point to the float saga. I replaced my second set of floats ( never flew with the first set, engine bought new 12/2014 and had to replace them per rotax SB). They were the 2 dot style, and were in service until February this year. I noticed signs of issues, fuel smell and higher fuel consumption, so I weighed them. Both sets were in the 7 gram zone. So I bought and installed the new 188 floats. New they were only a little lighter than the other set, only .2 gram per pair. They worked fine, no problems. Annual time, June, they were checked again and found to be exactly the same weight as before. Then in late October/ early November I noticed higher fuel consumption but no smell or gas in the trays. So I checked them again. One set, left carb, the pair were 9 grams, the heaviest was 5.4 g. Right carburetor, the pair was 8.2g, heavy one 4.6g. I ordered 2 new floats and filed a warranty claim. I'm not complaining, just wanted to let everyone know that the float saga continues. Be safe and check your floats regularly.

How did the warranty situation turn out?

Floats
 

I a newbie to this Rotax, RV-12 club. I love the plane and the engines but I am troubled by the float situation. I weighed mine last week and one set was 6.52 and the other set was 6.7. So I put them back in and the engine if running fine. But it seems to me that Bing is on the third design and still having the same problems. In that situation either Bing or Rotax should belly up to the bar and pay the tab. The end users who keep buying their new, revised, (fixed) product, should not have to keep paying.

Am I understanding the situation correctly or am I missing something since I have only owned an RV-12 since February of 2018.

My plane was annualed before I bought it and the floats were all in limits. I was having a vibration problem and I weighed the floats to be sure they were not causing or contributing to the problem. I concluded the floats were OK.

But I have another annual in February and I am wondering what the floats will show then.

So at this point, I am just wanting to gather some background information so I can make a good decision in February.

Thanks Guys. This forum is so helpful to a new owner and many of you guys are treasure troves of information which you willingly share.

How about the Marvel-Schebler floats? Anyone have any new information about them?

Warranty
 

I don't expect any word on the warranty claim for several weeks yet. And it will be a credit back on the card from the supplier. This is how it worked back in 2015 with the original float SB. I have considered making my own brass floats like the ones in Holley carbs from the'60s and'70s. There were few problems with those, but are labor intensive to manufacture. I'm just not willing to try making my own, lots of work and plenty of failure modes. I'll keep using the Rotax units until they get it right. Or Marvel gets theirs working.

I emailed M-S several times asking them about their Bing floats with no reply. I specifically asked about their warranty. In my final attempt to contact them I asked if they actually value their customers - no response...

Is there a trend among LL100 users not having problems with floats and Mogas with E-10 in it having problems with sinking floats? Is German DIN spec Mogas, where Bing carbs are tested, that different from US Mogas?


Has anyone ever pulled a pair of these sinker floats that are overweight, and exposed them to heat and time, to see if they dry out and expel the fuel they've absorbed, and become usable again? In other words, maintain a rotatable "stock" of these in your hanger, for reuse, until Bing finds a good and proper vendor solution for these carb floats, in their product line? The material used is obviously porous, over time, or... it's degrading chemically, to the point of uselessness.

If it indeed is ethanol problem based, in theory, you should be able to soak and submerse them in distilled water, they would take on water, and then heat them to the point that the water turns to steam or a gas, and evacuate the ethanol with the water, since ethanol is hygroscopic. If the weight is then in spec, an external sealer of some sort, thin and light, should be considered, that's inert to ethanol and gasoline properties. Hollowed out blown glass sounds like it would work?

Yeah, I had the same problem. No response to any of my queries. Sure would like to have an option other than the standard Bing floats. I think I'm on my 4th set ...

I changed one carb over weight floats out last year and saved floats. Reweighed my floats for annual and out of curiosity also weighed old floats. After a year they dried out and are within spec. No way would I install them and then have them start sinking in a few days or months and cause a problem away from home. These were the first new design current as of November 2015.

I understand your position. Just wondering how it affects owners that are just flying their R-12 "around the patch" with the hangar near by. PM me if they are available for experimentation.