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E6 250 Piston failure


Mcrafty1

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It would not take much more over fuel to do this on a alummin high compression piston like that engine has.I remenber seeing the photos he posted before and it was burning on top maybefrom a crack so thats from over fuel or timing.If this is what it is i would say that it should have been easy to find before it went down by cut the fuel off each cylinder to cut the fuel knock back.

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glenn akers

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Well, shes back together and running sweet....on less fuel, and with the new turbo its making 19lbs boost so more air and less fuel may mean less of a chance of a reoccurring piston issue. Im hoping this is the last time im into this engine in my working life.......time will tell. Thanks to all for the pointers on possable reason but i found no smoking guns this time.

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16 hours ago, kscarbel2 said:

Any time one "turns up the fuel", they're simultaneously asking for trouble. 

If I had a dime for every time I've heard a version of this story.......

I have set the fuel up on many engines in my younger days but most of them knew how to take care of it. But my question is all who wants more power always say I will only use it sparely but I say why in the first place because when you get tired and sleepy your going to mash on it till you get home. I do.

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glenn akers

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19 minutes ago, theakerstwo said:

I have set the fuel up on many engines in my younger days but most of them knew how to take care of it. But my question is all who wants more power always say I will only use it sparely but I say why in the first place because when you get tired and sleepy your going to mash on it till you get home. I do.

In the old days, if they wanted to block off the puff limiter altogether, or install a 691GC218CP6 puff limiter (the version with the least affect....there's a Service Bulletin), I had no problem with that. But I never encountered a good customer experience from turning up the fuel.

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I'm NOT a mechanic. But could you have swapped that injector with say, no 6 injector? Then if problem still occurs then may not be injector. And if no 6 piston melts like previous no 5 it could be injector issue?

Just thinking outside of the box. 

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a couple of thoughts here is there any thing different in the intake runner of the #5 cyl.? also I have never been around a 250hp e-6 but 19 lbs. of boost sounds low to me, I know a e6 350 will do 28 -32 ish,  so do you have a cooler issue?  also did any one pre oil this engine before installing the pan to verify that #5 cooling nozzle is performing correctly? also did you check the rocker arm travel on #5 verses the other cyl's?  i'm  thinking bad cam lobe on the intake could cause it to run hot of not getting enough air.

  

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9 hours ago, gearhead204 said:

a couple of thoughts here is there any thing different in the intake runner of the #5 cyl.? also I have never been around a 250hp e-6 but 19 lbs. of boost sounds low to me, I know a e6 350 will do 28 -32 ish,  so do you have a cooler issue?  also did any one pre oil this engine before installing the pan to verify that #5 cooling nozzle is performing correctly? also did you check the rocker arm travel on #5 verses the other cyl's?  i'm  thinking bad cam lobe on the intake could cause it to run hot of not getting enough air.

  

No, nothing different with the intake....141/2 to 17 is the norm for boost, the cooling nozzle was checked and aimed to spec, rocker arm travel was checked and a visual of the cam lobes confirm its condition to be like the others.  

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14 hours ago, gearhead204 said:

a couple of thoughts here is there any thing different in the intake runner of the #5 cyl.? also I have never been around a 250hp e-6 but 19 lbs. of boost sounds low to me, I know a e6 350 will do 28 -32 ish,  so do you have a cooler issue?  also did any one pre oil this engine before installing the pan to verify that #5 cooling nozzle is performing correctly? also did you check the rocker arm travel on #5 verses the other cyl's?  i'm  thinking bad cam lobe on the intake could cause it to run hot of not getting enough air.

  

Your 350 is hot not the norm the Boost your getting is what a E7 400 would make! 

he mentioned the cooler was aimed earlier in the post!

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2 hours ago, theakerstwo said:

Another ideal about the piston cooler,It may have been aimed at some time but that would be with the piston out.It would be easy if the cooler is still in the block to get bent bythe rod when installing the piston.

The cooler is aimed right, I have been on my back guiding the connecting rod down by the nozzle the last two times so I'm sure it is still right. I do believe the fuel pressure was to much and I also believe that number five must be the 'hot hole' in these engines. Time will tell, I cut the fuel back enough so I haven't seen the pyrometer go above 875 degrees....before I turned it back I could run it up into the 1000s without much effort.

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I understood that the cooler nozzle  was aimed , my question is ..... has its proper operation been verified!  as for the boost on the 350's  that would explain why the 4 or 5 I ever ran I liked so well..... could always make a 400 cummins look sick!

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5 hours ago, gearhead204 said:

I understood that the cooler nozzle  was aimed , my question is ..... has its proper operation been verified!  as for the boost on the 350's  that would explain why the 4 or 5 I ever ran I liked so well..... could always make a 400 cummins look sick!

I can't say for sure that it was......but would it go for two years between pistons if it were not working? I talked with a man yesterday that has a 400 and has the same experience with his......since he cranked it up, #5 every time, I'm hoping between my old turbo not up to par and cutting the fuel back that I am going to be running this motor longer than the last two.

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maybe one of the engineers will chime in here, but I always understood that the oil spray was to aid in heat removal from the underside of the piston , the  ill performing turbo I would suspect would be another major factor especially in a fueled up engine, if over fueled during long pulls. as for why #5 every time if this is the case? that's what brings me back to the cooling nozzle.  I would think if the block had a bad internal casting on the web around #5 liner that retarded coolant flow we would see piston skirt and liner damage similar  to  cold seizing in a two stroke.        

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2 hours ago, gearhead204 said:

maybe one of the engineers will chime in here, but I always understood that the oil spray was to aid in heat removal from the underside of the piston , the  ill performing turbo I would suspect would be another major factor especially in a fueled up engine, if over fueled during long pulls. as for why #5 every time if this is the case? that's what brings me back to the cooling nozzle.  I would think if the block had a bad internal casting on the web around #5 liner that retarded coolant flow we would see piston skirt and liner damage similar  to  cold seizing in a two stroke.        

That darn retarded coolant...........

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  • 3 weeks later...
On 08/28/2016 at 3:08 AM, Timmyb said:

I'm NOT a mechanic. But could you have swapped that injector with say, no 6 injector? Then if problem still occurs then may not be injector. And if no 6 piston melts like previous no 5 it could be injector issue?

Just thinking outside of the box. 

Thanks, the injector was swapped around and even relaced the last time

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