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Dle-20 Blew up....

Old 01-29-2011, 08:55 PM
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KoleDeRacer
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Default Dle-20 Blew up....

Well everyone today my dle-20 blew up.
Crank shaft pin broke but there was no other real damage besides the bearing from rubbing on the broke crank.
There are no signs of to much heat or not enough oil anywhere everything looks fine.
I use bel-ray oil at 40-1 ratio and have about 4 gallons through the motor now.
The plane was on a pretty gentle upline at full throttle when it let go.
Let me know what you guys think here is a few pictures.



Old 01-29-2011, 08:58 PM
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KoleDeRacer
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Default RE: Dle-20 Blew up....







Old 01-29-2011, 09:01 PM
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Default RE: Dle-20 Blew up....

A new crank is $25 with the bearing on it

A gasket set is $5
Old 01-29-2011, 09:06 PM
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jedijody
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Default RE: Dle-20 Blew up....

Blue crank bearing rollers do show signs of excess heat. I've said it many times, 32:1 minimum is required to keep the DLE20 alive. Pull the wrist pin and and post a couple pictures of it.
Old 01-29-2011, 09:08 PM
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KoleDeRacer
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Default RE: Dle-20 Blew up....

Its not actually blue like it looks it the picture just the way it came out.
Old 01-29-2011, 09:21 PM
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KoleDeRacer
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Default RE: Dle-20 Blew up....


My phone seems to add some blue with the picture but it is really not the paper towel is all white not blue
Old 01-29-2011, 09:47 PM
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KoleDeRacer
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Default RE: Dle-20 Blew up....

Btw jodi do you have parts in stock?
Old 01-29-2011, 09:49 PM
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Turd
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Default RE: Dle-20 Blew up....

This engine has a static timing of around 38 degrees before top dead center, the advanced timing is way too much as well, the number escapes me now. In my world that will break a crank and tear bearings out. The engine is trying to run in reverse and it would if it had a lower compression ratio the compression ratio of 10.5 to 1 and 38 degrees of static timing are engine killers. I took my timing to about 30 degrees where it should be and I see no difference in output. Sorry about your engine and I hope and trust you will be able to repair it
Old 01-29-2011, 10:52 PM
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Default RE: Dle-20 Blew up....



Yup, no problem, I have the parts.

Old 01-30-2011, 12:05 AM
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a1pcfixer
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Default RE: Dle-20 Blew up....

Looking at photos 5 & 7, it looks like there's galling on the shoulders maybe?
Old 01-30-2011, 05:46 AM
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mpascual
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Default RE: Dle-20 Blew up....


What model of ignition comes with the engine ?
#1 , #3 or #4 ?

This is very important to set the timing on DLE engines.

Regards
Old 01-30-2011, 06:46 AM
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KoleDeRacer
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Default RE: Dle-20 Blew up....

The galling happened after it was blown up more then likely from the prop turning on the way down and getting scratched on the crank.
The ignition is model A-01
Old 01-30-2011, 07:01 AM
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SkyPilot101
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Default RE: Dle-20 Blew up....

The pic's are not ideal, but looking at the broken edge of the crank pin, you see how smooth it is? This is indicative of what is called "brittle fracture" The pin is hard, but brittle, probable cause is improper heat treatment or lack there off. Hope it's just an isolated case, and probably is. China's steel making practices are some what questionable IMHO.

I do own one 20, and so far would buy anouther without question.
Old 01-30-2011, 11:25 AM
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Default RE: Dle-20 Blew up....

.....very true!

And it can also be a defective machining.

Copied from http://en.wikipedia.org/wiki/Fatigue_(material)

"In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the ultimate tensile stress limit, and may be below the yield stress limit of the material.
Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, microscopic cracks will begin to form at the surface. Eventually a crack will reach a critical size, and the structure will suddenly fracture. The shape of the structure will significantly affect the fatigue life; square holes or sharp corners will lead to elevated local stresses where fatigue cracks can initiate. Round holes and smooth transitions or fillets are therefore important to increase the fatigue strength of the structure."
Old 01-30-2011, 02:24 PM
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Default RE: Dle-20 Blew up....

yea, a good look at the pin should give some good insight into what happened. If its all a sharp shear then that would suggest fast fracture, which really isn't very preventable, just flawed material.
Old 01-30-2011, 07:02 PM
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Default RE: Dle-20 Blew up....

Jody: Just so I'm clear on the 32:1 ratio rec: the higher ratio is a function of the increased need for lubrication in the smaller displacement engine (20), right? Not necessary for the 55 or 30? Sorry for the slightly off topic post.

Old 01-30-2011, 07:31 PM
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Default RE: Dle-20 Blew up....

The paper work that came with my 55 also says 32:1
Old 01-30-2011, 08:00 PM
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Default RE: Dle-20 Blew up....

The oil ratio had little to do with the crank pin falure.
Old 01-30-2011, 08:20 PM
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Default RE: Dle-20 Blew up....

Sorry but I have to say - Why??

I have seen this type of failure so many times on DLE stuff.

Why?
You get what you pay for.
Let the flaming begin.

Ronster
Old 01-30-2011, 08:51 PM
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Default RE: Dle-20 Blew up....


ORIGINAL: wjcalhoun

Jody: Just so I'm clear on the 32:1 ratio rec: the higher ratio is a function of the increased need for lubrication in the smaller displacement engine (20), right? Not necessary for the 55 or 30? Sorry for the slightly off topic post.
The DLEfactory recommends and it isstated in ALLDLE factory manuals for ALLDLE engine models 30:1 fuel/oil ratio. However, exceptfor the DLE20,all DLE engines purchased from VVRC(which I administer the warranty for), if a high quality synthetic or mineral oil is used, can be run at a leaner saturation but a good rule of thumb to follow for minimum oil content is 40:1 for mineral oils and 50:1 for synthetics. Personally I prefer 32:1 in all engines all the time forever,.. period.

The DLE20, due to it's small size, high loads for it size and the high RPM it's commonly run at must use a minimum of 4 ounces of oil to 1 gallon of gasoline (32:1).

I won't go into what I define as high quality oil again hereexcept that it should be labeled for use solely in air cooled engines, be certified by the APITC, or TC+, and or meet JASO FC, FD requirements, and that Lawnboy and Amsoil are not fit for use in any DLE engine.

For the purpose of warrantyno onecan legally tell anyone what oil brand or typethey must use, only the requirements the oil must meet and that failures due to lack of lubrication are not covered under warranty. Whetherone purchases the engine from VVRC or anyone else, the end user, or anyone elseviewing pictures of it on their computer, does not determine cause of failureor whether a failure will qualify for awarranty claim. For this reason I recommend that all end users consult withtheir selling dealer on questions of oil type and content if they are not willing to follow the DLE manual guidelines.
Old 01-30-2011, 10:26 PM
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Default RE: Dle-20 Blew up....

I just want to say that i am in no way trying to get this covered under any warranty at all. The failure is 100% on me also that i would buy another dle-20 today and i will fix this one and keep flying it i really enjoy the little motor. Also there are probably a lot of other things that contributed to the failure it has had a prop strike or two in its life and i was never exactly gentle to it. I wanted to see what it what capable of and it has actually exceeded my expectations. Besides the fact that the crank pin broke the internals looked great almost no carbon build up and very little wear in general i plan to re-use the cylinder, piston, ring and maybe the rod. Overall this is a great motor and i would still recommend this engine to anyone. Engines fail it happens and is not limited to one brand (I own a DA-60) and i know DA-50 have failed before, its just part of it.

Old 01-30-2011, 11:20 PM
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Default RE: Dle-20 Blew up....

I understand and I didn't think you were looking for warranty consideration. But there are so many new gas engine users here, many are our customers, many are not, I seem to be the only factory authorized technician helping users out so I have to qualify some types of advice I give to protect those that have purchased their engines from other retailers that may not agree with my methodology. Of course, any customer of VVRC following my advice in these forums would have no problem were something to happen to their engine.
Old 01-30-2011, 11:28 PM
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Default RE: Dle-20 Blew up....

Exactly and that is what makes a good active dealer network so important. And if i had know about VVRC when i bought the engine (Just really started getting on the forums when i bought it) i would have for sure bought it from you because having an active dealer adds a huge amount of value for me to any product. Anyway give you a call tomorrow about parts.
Old 01-31-2011, 02:46 AM
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Default RE: Dle-20 Blew up....

They are paring out weight without increasing quality necessary for longevity. Either put a few more grams of material back into the crank or start doing better QC.
Old 01-31-2011, 01:11 PM
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Default RE: Dle-20 Blew up....

Mine did the same thing on the first start. just got the replacement DLE 20 Friday. Ran a tank though it sunday and it ran fine. Just wanted to add I had the same issue on it's first start for anyone keeping track of this issue. I posted pictures of the H9 Hellcat Around page 99 on the other form.
JT
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