Strange problem with Aerovee
Posted: Thu Jun 05, 2014 9:01 am
by radfordc
A guy near here called me last night to discuss his engine problem. He has a tri-gear Sonex with Aerovee. He has had engine problems in the past that required him to overhaul/rebuild the engine. He set the compression to 7:1 and is currently using 91 octane mogas. Because he is very low time in the Sonex he had a test pilot fly the plane after the engine work. The engine started and ran well initially. For the first 20 minutes the engine performed well, with CHTs in the low 300s and oil temp in the 180-190 range. After 20 minutes the oil temp suddenly rose to 200 and the engine started to run rough (apparently the CHTs didn’t go up much). When the plane landed the engine died. The owner reported that the engine was very hot, and even over an hour later was too hot to touch.
I’m at a loss to tell him what the problem is? Usually when and engine has been running well and then goes rough I suspect detonation, but that should result in high CHTs, not high oil temp. I suggested he change to 100LL and also shut off the electronic ignition system in flight and see if the problem continues. Any other good ideas?
Re: Strange problem with Aerovee
Posted: Thu Jun 05, 2014 11:37 am
by daleandee
radfordc wrote:I suggested he change to 100LL and also shut off the electronic ignition system in flight and see if the problem continues. Any other good ideas?
My best recommendation would be to install a 3.0 Corvair in it … 
Besides that I think your advice was spot on. I had an issue with the Aerovee that I had that was very similar. It was a very hot day (OAT 100ºF) and I was running 93 octane. Shortly after take-off the EGT’s were in the 1500ºF range and climbing. Of course CHTs were high also but the problem was the engine leaning out due to so much heat under the cowling.
Perhaps his CHTs aren’t reading correctly (the head fin mounted ones are “generous” as you yourself have documented). What were his EGT readings? Does he have the pants and fairings installed? What was the reason for the recent rebuild? If he is a low time pilot I would guess the engine was low time before the first rebuild. Perhaps he assembled the engine and the timing is not correct. When I first got my Aerovee the initial builder had the timing off on the cam gear by THREE teeth and it ran. It wouldn’t idle and top RPM was 2500 but it ran. Don’t know what the result would be if it was only one tooth off. Looking through the oil fill hole (where the distributor used to go) with a good light and turning the prop will allow you to see the gears and the timing marks. Just a thought.
What you have given was good advice. 100LL, a very cool and smooth morning flight, over the airfield. I’d also suggest covering the gascolator and adding a blast tube and possibly wrapping the exhaust. As you know the Aerovee works very hard and runs very warm. If he can keep it cooler under the cowling I believe his concern will go away. More break-in time will help also.
Dunno if this helps …
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
64.0 hours / Status - Flying
http://kitplanes2.com/blog/2013/12/ownerbuilder-2/
http://www.youtube.com/channel/UC49h6Qijc17_Ebfz0CbRFtg
Re: Strange problem with Aerovee
Posted: Thu Jun 05, 2014 12:37 pm
by vigilant104
The part about normal CHTs with abnormally high oil temps is interesting. Could he have an oil flow problem (pump, pressure adjust/regulator valve, etc)? If the oil isn’t circulating well through the oil cooler and the day is hot, the OT will climb. Did he mention anything about the oil pressure?
As to why it would run rough and quit on the ground–that sounds unlikely to be related to the “oil flow” theory I’ve proposed above.
Re: Strange problem with Aerovee
Posted: Thu Jun 05, 2014 2:15 pm
by radfordc
daleandee wrote:Perhaps his CHTs aren’t reading correctly (the head fin mounted ones are “generous” as you yourself have documented). What were his EGT readings? Does he have the pants and fairings installed? What was the reason for the recent rebuild? If he is a low time pilot I would guess the engine was low time before the first rebuild. Perhaps he assembled the engine and the timing is not correct. When I first got my Aerovee the initial builder had the timing off on the cam gear by THREE teeth and it ran. It wouldn’t idle and top RPM was 2500 but it ran. Don’t know what the result would be if it was only one tooth off. Looking through the oil fill hole (where the distributor used to go) with a good light and turning the prop will allow you to see the gears and the timing marks. Just a thought.
What you have given was good advice. 100LL, a very cool and smooth morning flight, over the airfield. I’d also suggest covering the gascolator and adding a blast tube and possibly wrapping the exhaust. As you know the Aerovee works very hard and runs very warm. If he can keep it cooler under the cowling I believe his concern will go away. More break-in time will help also.
His plane is a tri-gear and also has oversize tires so I’m sure it’s “draggy”. He claims that he can only get 3200 rpm max (Sensenich prop) but isn’t certain about the accuracy of his tach. He has worked with the Aerocarb trying to get it right and claims that the engine runs great initially until it gets hot. You’re right about the gascolator maybe being part of the problem. I should mention that to him. I guess it’s possible the timing could be off too, but that doesn’t fit with the engine running good at first.
He doesn’t have an EGT instrument so can’t tell about that.
Thanks for the input.
Re: Strange problem with Aerovee
Posted: Thu Jun 05, 2014 4:51 pm
by kmacht
Since this is happening just after re-building the engine I would check the valve adjusters to make sure they are set correctly as well as check the torque on the head bolts. As the engine gets hot it could be the valve timing getting too far off if they weren’t set correctly when cold. The 10 degree increase in oil temperature doesn’t seem like that big of a deal to me. I would be more concerned with the rough running engine. If it is just happening when getting hot then he should be able to duplicate it on the ground. If it were me I wouldn’t go fly it until it was sorted out.
Keith
Re: Strange problem with Aerovee
Posted: Thu Jun 05, 2014 11:41 pm
by wlarson861
Sounds like the “Aerocarb Burps”. I removed my gascolator and went with a straight fuel line and 40 micron filter. The burps dont usually start right away but after the engine compartment is heat soaked. Mine never burped on the ground with the cowl off but would burp on hot days while doing run up or shortly after.
Re: Strange problem with Aerovee
Posted: Fri Jun 06, 2014 8:09 am
by radfordc
I agree that it sounds like a hot fuel issue. I talked to Fred and advised him to wrap all his fuel lines with insulation and see if the problem goes away. Also, to use 100LL instead of mogas.
Re: Strange problem with Aerovee
Posted: Sat Jun 07, 2014 5:51 am
by floridasonex
“Of course CHTs were high also but the problem was the engine leaning out due to so much heat under the cowling.
Dale Williams”
Wouldn’t having too much heat under the cowl mean less dense air and cause it to be RICHER? I’ve installed a
cockpit controllable fresh air intake (not sealed to carb) that places fresh air right in front of the air filter. I also
have a sensor in the aeroinjector right below the slide. Opening the fresh air intake lowers the temp in the carb
by about 30 degrees inflight. When I do this it’s putting more dense air into the carb and the EGT rises (leans). I
then have to richen the mixture slightly.
RT
Re: Strange problem with Aerovee
Posted: Sat Jun 07, 2014 1:48 pm
by daleandee
floridasonex wrote:Wouldn’t having too much heat under the cowl mean less dense air and cause it to be RICHER?
RT
No. The problem for me was too much heat causing the fuel (93 Mogas) in the gascolator and perhaps the fuel lines and even the Aerocarb to boil causing bubbles and burps. Once I had insulated the fuel lines, covered and insulated the gascolator, and wrapped the exhaust the heat wasn’t causing this to happen anymore. Older cars with the fuel lines running too close to the exhaust could, when hot, get what was referred to as “vapor lock” but modern fuel injection and higher fuel line pressures have eliminated that.
Myunn (Corvair powered Sonex air frame) uses a float carb (Marvel Schebler MA3-SPA) and has had no issues with heat (the Corvair runs very cool), burps, stumbles, or hesitation of any kind. I have fire sleeve on the fuel lines and put a blast tube and cover on the gascolator.
Your thinking as far as the air into the carb is correct and may indeed be a contributor to the problem. With the Marvel Schebler I have direct ram air and carb heat for use when needed. I had an Aerocarb and flew it 175 hours but I now personally do not consider them to be airworthy. Just my humble opinion … please no flames!
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
64.0 hours / Status - Flying
http://kitplanes2.com/blog/2013/12/ownerbuilder-2/
http://www.youtube.com/channel/UC49h6Qijc17_Ebfz0CbRFtg
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 7:59 am
by floridasonex
"Your thinking as far as the air into the carb is correct and may indeed be a contributor to the problem. With the Marvel Schebler I have direct ram air and carb heat for use when needed. I had an Aerocarb and flew it 175 hours but I now personally do not consider them to be airworthy. Just my humble opinion … please no flames!
Dale Williams"
No flames. I see where you’re coming from. I’m not happy with the Aeroinjector either ..
RT
Strange problem with Aerovee
Posted: Sun Jun 08, 2014 10:50 am
by Sonex1517
Dale,
your opinion of the AeroVee is clear and well known.
However, to state there is something that is not airworthy is definitely inflammatory.
What facts - not opinions - do you base this statement on please?
I respect your opinion but this is a rather strong statement to make here without any representation of actual data to back it up.
Robbie
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 12:11 pm
by MichaelFarley56
I certainly have no intention on entering a heated debate over this topic, but I would like to add that I am using an unmodified AeroInjector and an unmodified #2 needle and have no issues. When I first started flying I had to figure out how to properly set the unit up, but that’s no fault of the design. With well over 100 hours on my airplane I’m very happy with it!
I’ve looked at the Rotec TBI and others, but LOVE the simplistic nature and ease of setup of the AeroInjector. No fuel pump, no primer, no carb heat, etc. If we want to use the KISS method (Keep It Simple Stupid!), I’d say the AeroInjector wins hands down!
If people are having issues with their AeroInjectors, perhaps they could describe the symptoms online here so we can all help isolate the issues and get the problem fixed. Ultimately, I have a feeling that the few people with “issues” are making themselves heard while hundreds upon hundreds of others are happily behind their AeroInjectors with no trouble at all. I firmly believe it’s a good product and I can’t wait to fly my AeroVee/AeroInjector equipped airplane to AirVenture here in a few months!
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 2:58 pm
by radfordc
There have been enough cases of people complaining about how badly there Aerocarb performs to at least be cautious. I cringed a little hearing Dale make that comment, but I understand that it’s just his opinion and is entitled to it. I’m sure that the “real carb” that Dale is using is a very good performer.
Certainly, there are far more satisfied Aerocarb users than not. I will say that having had a bad case of the “burps” once it definitely will shake your confidence for a little while.
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 3:07 pm
by radfordc
MichaelFarley56 wrote:If people are having issues with their AeroInjectors, perhaps they could describe the symptoms online here so we can all help isolate the issues and get the problem fixed. Ultimately, I have a feeling that the few people with “issues” are making themselves heard while hundreds upon hundreds of others are happily behind their AeroInjectors with no trouble at all. I firmly believe it’s a good product and I can’t wait to fly my AeroVee/AeroInjector equipped airplane to AirVenture here in a few months!
Mike, if the fuel in the line going to the carb vaporizes and causes bubbles the engine will stumble and run badly…if not stopping all together. There is no “bowl” to allow the bubbles to dissipate like on a real carb. I had it happen once and was lucky to be near the runway or I would have had to do a forced landing. The fix is of course to prevent heat build up in the fuel…lots of insulation of the lines and gascolator, maybe eliminating the gascolator, and using a less volatile fuel like 100LL.
The only other “issue” I’ve noticed is that in order to get the engine to run rich enough during takeoff the needle is a little too rich at idle. I compensate by pulling the mixture control lean on the ground. Not much of a problem.
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 8:31 pm
by MichaelFarley56
Thanks Charlie. I was having “burps” on takeoff but I traced it an incorrectly mounted digital fuel flow sender. Once I removed that from the system, I haven’t had an issue since. I do have my stock gascolator and fuel line insulated as you stated.
I also lean out my engine on taxi and in cruise. Normally my mixture is full rich on takeoff and climb, leaned slightly in cruise, and leaned a lot for taxi. I find this to be no issue though!
Re: Strange problem with Aerovee
Posted: Sun Jun 08, 2014 8:44 pm
by daleandee
Sonex1517 wrote:Dale,
your opinion of the AeroVee is clear and well known.However, to state there is something that is not airworthy is definitely inflammatory.
What facts - not opinions - do you base this statement on please? I respect your opinion but this is a rather strong statement to make here without any representation of actual data to back it up.Robbie
Hi Robbie,
What I said was,
I had an Aerocarb and flew it 175 hours but I now personally do not consider them to be airworthy. Just my humble opinion
As for the Aerovee, I believe they are good engines and serve the Sonex community very well. I have no heartburn with VW power but my humble opinion is that in a Sonex the Aerovee works very hard and leaves the aircraft a bit under powered for two place operations on hot days. If the aircraft is light, the pilot and passenger are not large, and the OATs are not overly warm, the Aerovee performs adequately. Would I fly behind an VW power? Absolutely.
My comment was directed at the Aerocarb.
Everyone has to decide for themselves what level of risk they are willing to assume in any endeavor they undertake. Flying is no different. I purposely used the words “personally” and “my humble opinion” to make the point that for me, a decision that I have come to in my personal flying career is that I won’t again fly behind an Aerocarb. That’s all I meant to say.
To say that you respect my opinion and then ask for facts (not opinions) as proof of what I believe is a bit disingenuous I would think.
The concerns with the Aerocarb are well known and clearly documented on this site and all over the web. I have no desire to go through a list of reasons that I find the Aerocarb to be out of consideration for me as an aircraft carb. Many have expressed their love of the Aerocarb and no one has asked them to “prove” anything as to why they believe what they believe.
I hope that this site does not become such a place that a man cannot state a personal opinion. If you feel comfortable flying behind an Aerocarb you have the right to do so and come here and share that.
My question to you is; how many hours have you personally flown behind and Aerocarb? Would it be too much to ask you to give me your experiences with the Aerocarb?
Respectfully,
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
64.0 hours / Status - Flying
http://kitplanes2.com/blog/2013/12/ownerbuilder-2/
http://www.youtube.com/channel/UC49h6Qijc17_Ebfz0CbRFtg
Strange problem with Aerovee
Posted: Sun Jun 08, 2014 11:41 pm
by Sonex1517
Whoosh. Flame on indeed.
You know exactly what you said and “airworthy” is a strong word with specific meaning. We live in a society where words do carry weight, and this is exactly the tone we are trying to avoid here on a technical forum. Stick to facts.
If I’d meant to censor you I would have done so. I am a moderator. Your opinion is fine. But the words have meaning my friend…and that was a strong statement to make.
I have never claimed to have any experience with an AeroVee. Nor have I said I do.
Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved
Re: Strange problem with Aerovee
Posted: Mon Jun 09, 2014 6:50 am
by rizzz
Sonex1517 wrote:Whoosh. Flame on indeed.
You know exactly what you said and “airworthy” is a strong word with specific meaning. We live in a society where words do carry weight, and this is exactly the tone we are trying to avoid here on a technical forum. Stick to facts.
If I’d meant to censor you I would have done so. I am a moderator. Your opinion is fine. But the words have meaning my friend…and that was a strong statement to make.
I have never claimed to have any experience with an AeroVee. Nor have I said I do.
Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved
Hi Robbie,
I’m sorry but I must disagree,
Yes, that was a strong statement but it was stated clearly as an opinion, not as a fact, and if this is how Dale feels about the product I think he should be allowed to express that opinion and I don’t see how he could word it differently or why he should even do so.
Others might disagree with this opinion and choose to respond (as they have here), and so the topic might turn into a debate, but as long as we can keep it civilized, debate is good, people get a good idea about the different opinions of actual customers of the product, and yes, some very strong opinions, but that does not mean they should not be heard.
Just my opinion 
Re: Strange problem with Aerovee
Posted: Mon Jun 09, 2014 9:06 am
by kmacht
Can we get away from the chest thumping and back to the facts again? Dale said that after flying behind an aerocarb for 175 hours he now doesn’t feel like it is airworthy anymore. Without everyone getting all emotional about it I would like to hear from Dale as to why he feels this way. I am assuming that he had some experience that is driving this belief and would like to know what it is. I am getting close to a first flight and want to hear the good as well as the bad so I know what to expect, what to look out for, and maybe what to do or not to do since my engine has the aerocarb installed. Without time behing an aerocarb myself I am reliant on other peoples experiences to help form my own opinion as to what is or isn’t safe and airworthy. Yes there are many other people who are probably flying behind the aerocarb trouble free. Nobody is forcing you to make form an opinion based on on one persons experience but the more information that is out there the more there is to consider. So.. Dale if you don’t mind can you please explain the issues you had with the aerocarb and why you feel the way you do. To the others. Please let him state his case withou jumping all over him. The last thing we want is for this forum to get the reputation of being hostile to anyone that may have had a problem with a sonex product. Let’s keep the personal attacks to a minimum.
Keith
#554
Re: Strange problem with Aerovee
Posted: Mon Jun 09, 2014 9:20 am
by Sonerai13
daleandee wrote:I had an Aerocarb and flew it 175 hours but I now personally do not consider them to be airworthy. Just my humble opinion … please no flames!
Geez Dale, you blast away at the AeroCarb/AeroInjector and then you plead for no flames. What’s up with that?? 
Seriously, though, I would be interested in WHY you have the opinion that the AeroCarb/AeroInjector is “unairworthy”. That’s a pretty strong statement, even if it is an opinion. To have that strong of an opinion, you must have some reason. Inquiring minds want to know!
with almost 500 aircraft flying in the Worldwide Sonex Aircraft fleet, the vast majority of which using AeroCarbs or AeroInjectors, plus many AeroCarbs/AeroInjectors flying on other experimental aircraft with all types of engines, I think the airworthiness speaks for itself. Heck, I have nearly 200 hours flying behind AeroInjectors myself! I certainly wouldn’t use the term “unairworthy” when talking about the AeroInjector. And I’m sure there are people reading this forum who have a lot more time behind an AeroInjector than I do. I don’t think the word “unairworthy” comes to their minds either.
So, let us know why you feel so strongly. I, for one, would really appreciate it.
Thanks!