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Author Topic: HELP Engine runs have turned sour!!  (Read 3831 times)

Offline frank mccune

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HELP Engine runs have turned sour!!
« on: August 04, 2016, 01:21:39 PM »
       Hi All:

        I have been getting terrible engine runs from my two favourite stunt engines. They just started to run in a very ragged and uneven staccato despite how I adjust the needle valves.  I can not get a steady run in either a 4 cycle or rich 2 cycle.

      I am using a new fuel mix that is:
5% nitro
12% synthetic oil
12% castor
The reminder is alcohol.

The engines are a HP .40 Gold Cup with a custom NVA and venturi and an OS .40 Stunt circa 1960's with stock venturi and NVA  Both engines are in great nick and are easy to start.
The props are both wooden 10x6.
The temps have increased to 80-94 degrees while flying.

Does Summer heat demand more nitro such as 10-15%?

Perhaps I need to have a larger prop load on these engines such as an 11x6 to get them to work?  The HP used to love to run in a wet 4 cycle or a wet 2 cycle.  I do not remember it breaking 4-2-4.  The OS has run a perfect 4-2-4 in the past.

The HP is mounted on a Twister and the OS is installed on a Nobler.  Both planes very well despite the rough running engines.

There is no vibration problem with either plane.

Changed plugs in both engines.

The common denominator here may be the fuel.  Perhaps I should mix a small sample batch of fuel with 15% nitro and see if there is any change.  If so, I am on the right path.

What can I do to get a good steady run from these engines?

                                                                                                                           Tia,

                                                                                                                           Frank McCune
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Offline Mark Scarborough

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Re: HELP Engine runs have turned sour!!
« Reply #1 on: August 04, 2016, 01:27:25 PM »
you say "new fuel mix" is it a new batch?
is it a new formula?
is it new ingredients?
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Offline Steve Helmick

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Re: HELP Engine runs have turned sour!!
« Reply #2 on: August 04, 2016, 03:00:20 PM »
I'd mix up a pint or quart of 10%...but I'd also be suspicious of your alcohol being contaminated by H2O.

Personally, I'd try Thunderbolt 4c/Big Bore glowplugs in both engines, and would be using something larger diameter and lower pitch on a .40. The TT 11x4.5 might be the ticket. That, or an 11-5 Zinger Pro (reworked to resemble a propeller). Where (roughly) are you again?  H^^ Steve   
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Online RandySmith

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Re: HELP Engine runs have turned sour!!
« Reply #3 on: August 04, 2016, 03:13:29 PM »
Sounds like water in the fuel
If you cannot get a stable needle setting  try another fuel

Randy
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Offline frank mccune

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Re: HELP Engine runs have turned sour!!
« Reply #4 on: August 04, 2016, 04:31:38 PM »
     Hi All:

     I think that you may have something with the idea of water in the fuel! This is the first batch of fuel that I mixed by using a "new" supply of alcohol.  That is the only ingredient that is new to the mix! I will try an A-B test tomorrow with a fuel of known quality.

     How does one remove water from alcohol?
   
                                                                                                                            Thanks for the replies,

                                                                                                                            Frank McCune

       
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Online Brett Buck

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Re: HELP Engine runs have turned sour!!
« Reply #5 on: August 04, 2016, 07:15:58 PM »
Quote from: frank mccune on August 04, 2016, 04:31:38 PM
 I think that you may have something with the idea of water in the fuel! This is the first batch of fuel that I mixed by using a "new" supply of alcohol.  That is the only ingredient that is new to the mix! I will try an A-B test tomorrow with a fuel of known quality.

     How does one remove water from alcohol?

    As a former resident of the Kentucky hill country, it involves the use of thump kegs and coils of copper tubing. There aren't a lot of practical methods for the home user that won't get you in trouble with the rev'nuers. 

    By alcohol, you mean methyl alcohol AKA methanol, right, not ethyl?

     Brett
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Offline frank mccune

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Re: HELP Engine runs have turned sour!!
« Reply #6 on: August 05, 2016, 06:08:18 AM »
     Hello Brett et. al.:

     When living in the "Old Country," I lived in an area where obtaining glow fuel was vey difficult.  I was offered free alcohol that was supposed to be ethyl that had been used for flushing the air lines on trains.  Any port in a storm!

      I used this stuff with castor, USP grade, at the time was $3.00 per gallon, 1973, and it worked!  The needle was a bit more sensitive to adjust but it worked well.  I imagine that it may have had a bit of water in it as that is why ethyl had been used.

      In retrospect, I bet that it was methyl alcohol!

      I guess that I am stuck with 5 gallons of contaminated alcohol!  Lol  I can see no reason to discuss this with the supplier as  they will inform me that it was my fault.  I doubt that they know how to store 300 gallons of alcohol without moisture forming in the storage tank.  They purchase 300 gallons at a time to run in their dirt track car. 

     Is there a method for checking to see if there is water in the alcohol? I know that a gas station can check to determine if there is water in their tanks with a simple dip stick test.  That is gasoline, and handles water in a different way.

                                                                                                                                  Thanks for the replies,

                                                                                                                                  Frank
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Offline John Eyer

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Re: HELP Engine runs have turned sour!!
« Reply #7 on: August 05, 2016, 07:49:50 AM »
For S&G's try adding up to 3% acetone to your bad glow fuel.  It might just smooth out your engine run. 
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Offline Steve Helmick

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Re: HELP Engine runs have turned sour!!
« Reply #8 on: August 16, 2016, 04:36:57 PM »
If I'd bought some alcohol from a race car shop and it didn't run right, I would go pay them a visit and casually ask if that last batch worked ok for their other customers. They may have already received a lot of complaints, so you may get the offer of a replacement batch. I'd have it in the truck, but wouldn't haul it inside until after I'd asked the question.

I hope there will be a final report on what you found to be the problem. Also, what the acetone did, if you tried that. I'd suggest being cautious about what it would do to the finish on your planes.  H^^ Steve
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Brian Hampton

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Re: HELP Engine runs have turned sour!!
« Reply #9 on: August 16, 2016, 07:40:02 PM »
Quote from: frank mccune on August 05, 2016, 06:08:18 AM
Is there a method for checking to see if there is water in the alcohol?
The only method I know of is to mix a small amount with oil to around a 20% mark (essentially a small batch of FAI type fuel) then put it in a fridge to cool it down. If the oil falls out of solution then there's water in the methanol. The temperature needed to drive the oil out depends on the % of water (and to a small extent the type of oil) but as a general guide 1% water falls out at about 40F and 2% at about 84F. It's actually a straight line graph of temp/% water.
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Offline Bill Johnson

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Re: HELP Engine runs have turned sour!!
« Reply #10 on: August 19, 2016, 08:54:50 AM »
Apparently, you can add anhydrous magnesium sulfate to the fuel, which will absorb the water, then filter out the AMS with a paper filter. That's how one guys says it's done in chemical labs. 500 grams of AMS is about $25, which might be enough to do it. Frank.

How much of the fuel did you mix up?
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Offline frank mccune

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Re: HELP Engine runs have turned sour!!
« Reply #11 on: September 10, 2016, 07:35:25 AM »
    Hello All:

    I thought that I should post the solution that I found for my engines running poorly.  This may help others in the future if the similar problem happens to the.

    The problem was the glow plugs! The plugs that I was insisting upon using were circa 1970-1980 and were used.  They glowed like they should but did not work well in flight.  It must have been due to some "aging process." I replaced the plugs with unused plugs and the problem was solved. I aint smart enough to figure out what happened with the plugs, but I know that they did not work despite looking good. I had no idea that if it looked good, it could be bad.  Sounds like some women that I have met! Lol

     Oh yes, I had a stash of new Fireball plugs with the price of 39 cents marked on them. They worked as they should. That was some time ago that I purchased these plugs! Lol

      Thanks for taking the time to reply.

                                                                                                                    Be well,

                                                                                                                    Frank McCune
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Offline Steve Helmick

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Re: HELP Engine runs have turned sour!!
« Reply #12 on: September 11, 2016, 03:16:21 PM »
There was a report some years ago, about a curious tendency for glowplugs to go TU during Winter storage. The theory was that it was some sort of corrosion, but also possibly related to after-run oil. I have had this happen once...worked for the last flight of Autumn but when Spring rolled around, it wouldn't start or glow.

With our tendency to run our engines on the wet side (or double-extra wet), it makes sense to use a hot glowplug. Brett says you likely can't run too hot a glowplug in a stunt engine, so I've been using mostly 4-cycle (Thunderbolt) glowplugs. These look like a standard glowplug, don't have an "idle-bar", and don't have an extended "snout" like the OS 4-cycle glowplug. I can't say I understand what makes a glowplug hot or cold, and am very willing to overlook the "why" details if they work, which they do.  #^ Steve
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Air Ministry .

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Re: HELP Engine runs have turned sour!!
« Reply #13 on: September 11, 2016, 08:47:52 PM »
You can efinately ' oil the plug ' with after run oil.  :P Connecting battery before its cleared with fuel , the plugs swamped ( HOW MUCH after run oil ?  ;D ) and wont fire untill enough flipping through clears it .
But a thought had occurred , was the oil cooking on the element / baking . Wrecking the plugs usefullness ,  :-\ .

If I removed the plug , blew it , generously primed the engine belting over sans plug ; then put the plug in & on with the battery , it'd fire right up .

The Old hydraulic lock trick with after run oil cant do the plug good . Sometimes motor oil ( 20/50 ) or atf for after run oil .
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Offline Chancey Chorney

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Re: HELP Engine runs have turned sour!!
« Reply #14 on: September 11, 2016, 10:11:14 PM »
Not to sound like an idiot, but could one not freeze the alcohol then strain out the ice that should form if there is any water in it? I had read to do this with some older rc fuel.
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Offline frank mccune

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Re: HELP Engine runs have turned sour!!
« Reply #15 on: September 12, 2016, 06:50:17 AM »
     Hello Again:

     Oh yes, the idea of freezing the fuel to see it  would separate the water from the alky reminds me of an bad experience that I had with frozen "shine." When I was 18 a friend of mine suggested that we drink some moonshine that he had scored.  It was in the trunk of his car and the temperature was below freezing.  We noticed that contents had separated into two distinct levels.  What did we know?  After the first slug, we both knew that we were not able to drink this stuff!  It seemed that the water had frozen in the bottom of the jar and the alky had risen to the top where it had to be pure!  All I can remember that it was brutal!! "Burns your tummy don't you know." Lol

     I have been flushing my engines with a carb or brake cleaner prior to fueling them to remove any after run oil.  It seems to make starting the engine easier. I just have a feeling that a plug would work better without being slathered in thick oil when heated for the first run. I think that this what Matt is alluding to in his reply  Would the oil burn off of the element and leave little to no fouling? I doubt it, but what do I know about how things chemically react within an engine? If castor oil produces a "varnish" on the cylinder and piston, does it also leave a varnish on the element of the plug? I still have about a pint of air tool oil but I doubt that it is any better than the ATF that I have been using for years.  Perhaps I will use it in my lawn and garden equipment engines for protection during  Winter storage.

    I recently talked with a friend who has started removing his plug after each flying session.  The idea of this is to store it without any "stuff" on the coil thus preventing fouling of the element.  The plugs that we purchase nowadays seem last so much longer than they did back in the day!

     Steve, I live in South Central Pennsylvania. 

     Enough for now.  Time to go flying!

                                                                                                                                 Be well,

                                                                                                                                 Frank McCune

   
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Offline Bill Johnson

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Re: HELP Engine runs have turned sour!!
« Reply #16 on: September 21, 2016, 12:06:15 PM »
Thanks for following up, Frank. It really does help us "retreads".

On your old plugs that weren't working in flight, did you check to see if maybe they were leaking internally? Install one, put a drop of dishwashing fluid on it, especially where the center electrode comes out, and turn the engine slowly so the piston comes up and see if your getting any bubbles on or around the plug.
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Offline FLOYD CARTER

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Re: HELP Engine runs have turned sour!!
« Reply #17 on: September 21, 2016, 01:01:03 PM »
I've heard of glo plugs growing "taters", whatever that is.  Some sort of crystal structure forming as little droplets on the plug element.  Apparently too small to be easily seen,  but it wrecks the plug for engine use.

Anytime I suspect a bad glo plug, I simply change it, without looking.  The usual symptom of a bad plug is a sudden drop in RPM when the battery is disconnected.

Floyd
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Online Brett Buck

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Re: HELP Engine runs have turned sour!!
« Reply #18 on: September 21, 2016, 02:02:15 PM »
Quote from: FLOYD CARTER on September 21, 2016, 01:01:03 PM
I've heard of glo plugs growing "taters", whatever that is.  Some sort of crystal structure forming as little droplets on the plug element.  Apparently too small to be easily seen,  but it wrecks the plug for engine use.

    The taters are usually pretty easy to see (I have no problem - as long as I get exactly the right strength Walgreen's reading glasses). They are usually a black rounded glob attached to the wire, usually near where it attaches to the body of the plug. If you scrape it, the black surface comes off and it's tan-colered underneath. Taters tend to form over the course of tens of flights and slowly reduce the power.

    A second issue that also matters is "frosting".  Plug elements tend to lose their shine over time anyway, and it's pretty difficult to tell whether or not the loss of shine is causing an issue or not, and a good used plug and a "frosted" plug are hard to distinguish.

      But certainly, if the engine just starts running strangely, the first thing to try is a replacement plug. If it doesn't improve anything, it wasn't the plug.

  Brett
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