I Don't Care How Many Motor's I blow up

[IBinSaneDiego]

I will get one to last beyond the 4th tank of fuel. I follow the break in procedures, I keep the temps in range, I take it easy and they still fail.
And then when they do go (the connecting rod breaks) which
causes it to break the piston and bending the lower part of the sleeve so that it can not be removed from the case. The last two I rebuilt using a new case/piston/sleeve so there's no warranty. Anyone want to sell me beach front property in the middle of the desert?

 

[Plaidfish]

what mills are you trying?
and exactly what are you doing when they break?
what temp gun are you using?
How exactly are you temping them?
have you taken them apart yourself after blowing them?
do you see any scoring on the sleeve, Like something got i n there?
do you try heating them up or adding some ARO before the first time you run it?
I clean em all before getting em going... new or used ones I've bought....

 

[IBinSaneDiego]

what mills are you trying?
and exactly what are you doing when they break?
what temp gun are you using?
How exactly are you temping them?
have you taken them apart yourself after blowing them?
do you see any scoring on the sleeve, Like something got i n there?
do you try heating them up or adding some ARO before the first time you run it?
I clean em all before getting em going... new or used ones I've bought....


*Mach 427
*this last one I was running in a oval pattern, giving it about 2/3 throttle on the straight which was no more than 100 feet. This was the third tank of fuel
(1st tank one was run at idle at about 220 degrees, then the 1st half of the 2nd tank too, on the rich side, and drove easy for the 2nd half)
* temp gun - Atomik - (I just opend the freezer and pointed it at a box and got 15.0 degrees.)
* yes, I have assembled/disassembled each one.
* This one I was extremely careful in oiling, and cleaning the parts before assembly, and switching between glow plugs.
* No scoring on the piston or sleeve
* It was well oiled before running the first time , and after each use. The first two tanks, run on seperate days, air temp about 65. Today it was kind of cool when it died (engine temp about 230)

 

[vbgagnon]

aro=after run oil.

Is there reputable member in san diago that could help out?

I know RevoRancher is in the OC somewhere, but Cali is quite large.

 

[wanabedriver]

I am a nitro noob, but what if you tried heating up the engine before you try starting it with a blow dryer or heat gun? I would guess that the sleeve and piston are really tight, making it hard on the connecting rod, causing it to snap when you try to start it? When you heat it, everything expands, sleeve faster than piston, so there is more play.

 

[olds97_lss]

Wow... that is strange... It almost sounds like its running way too rich aside from the temps. I've seen a guy break 2 OS 21 RG's with less than half a gallon on them the same way. Shattered the con-rods.

By the "running too rich" comment, it sounds like it's loading up and hydrolocking when it's running which is snapping the con-rod.

 

[Monkey Wrench]

I'm wondering, and let me stress WONDERING, if it is a head shim issue? Not knowing what kind of fuel you are running (10%, 20%, 30% nitro) I'm just thinking the head may not be shimmed correctly and the piston is slamming into the bottom of the head.

 

[Plaidfish]

sounds like you might be getting on it a lil earlier than you should....break in takes at least 6 tanks......I wouldn't be going 2/3 throttle for 100 ft on the 3rd tank...that alone sounds like a recipe for disaster....and teh idle first tank method is a lil questionable.....IMO it sounds like you're just getting too eager to run the thing before break-in is complete......

 

[Philster]

Break in just isn't done. Con rods break on overly rich engines during the fist 2-5 tanks of fuel.

If you want to drive it around for break in, you need to drive it only slightly rich.

O.S. engines supports this con rod breaking issue as well, noting that driving is proper for break in, but not with sloppy rich settings.

The engine needs to get warm/hot, not be too rich, just a tad rich, and you can give careful throttle. As the engine metals heat and cool, they harden, and they expand better, freeing up the piston. If you are ahead of this curve, then the con rod gives out, because something has to give.